EHP Library Malaria Bulletin 46: Sept 30-Oct 15, 2002

 

Announcements

1 - The October 3, 2002 issue of Nature is a special issue on Plasmodium genomics.
Full-text articles from this issue are on the web site at: http://www.nature.com/nature/malaria/ 

2 - The Mark V version of the trilingual (English/French/Spanish) Royal Perth Hospital Malaria Education CD-ROM is now ready for distribution to medical/educational institutions or centres FREE of charge, This CD-ROM should be particularly useful to those centres that do not have reliable internet access to our web site. The English  site can be accessed at: http://www.rph.wa.gov.au/labs/haem/malaria/index.html  The site contains sections on Diagnosis, Prophylaxis, Treatment and History as well as an innovative interactive "Test & Teach" self assessment module. It is an ideal site for Clinicians, Scientists, Healthcare Professionals and Students.

Graham ICKE, A/Principal Scientist, Division of Laboratory Medicine, Royal Perth Hospital Wellington St., Perth, Western Australia 6000.  Email: [email protected]
Malaria On-Line Project - http://www.rph.wa.gov.au/labs/haem/malaria/index.html

 

Social sciences and malaria

 

Trop Med Int Health  2002 Oct;7(10):813-22 
 
Prevention of malaria in Afghanistan through social marketing of
insecticide-treated nets: evaluation of coverage and effectiveness by
cross-sectional surveys and passive surveillance.
 
Rowland M, Webster J, Saleh P, Chandramohan D, Freeman T, Pearcy B, Durrani N,
Rab A, Mohammed N.
 
HealthNet International, Peshawar, Pakistan. London School of Hygiene & Tropical
Medicine, London, UK.
 
Malaria is often a major health problem in countries undergoing war or conflict
owing to breakdown of health systems, displacement of vulnerable populations,
and the increased risk of epidemics. After 23 years of conflict, malaria has
become prevalent in many rural areas of Afghanistan. From 1993 to the present, a
network of non-governmental organizations, co-ordinated by HealthNet
International, has operated a programme of bednet sales and re-treatment in
lowland areas. To examine whether a strategy based on insecticide-treated nets
(ITN) is a viable public health solution to malaria, communities were given the
opportunity to buy nets and then monitored to determine population coverage and
disease control impact. This was carried out using two contrasting methods:
cross-sectional surveys and passive surveillance from clinics using a
case-control design. Nets were purchased by 59% of families. Cross-sectional
surveys demonstrated a 59% reduction in the risk of Plasmodium falciparum
infection among ITN users compared with non-users (OR 0.41; 95% CI 0.25-0.66).
The passive surveillance method showed a comparable reduction in the risk of
symptomatic P. falciparum malaria among ITN users (OR 0.31; 95% CI 0.21-0.47).
The cross-sectional method showed a 50% reduction in risk of P. vivax infection
in ITN users compared with non-users (OR 0.50; 95% CI 0.17-1.49) but this effect
was not statistically significant. The passive surveillance method showed a 25%
reduction in the risk of symptomatic P. vivax malaria (OR 0.75; 95% CI
0.66-0.85). ITN appeared to be less effective against P. vivax because of
relapsing infections; hence an effect took more than one season to become
apparent. Passive surveillance was cheaper to perform and gave results
consistent with cross-sectional surveys. Untreated nets provided some
protection. Data on socioeconomic status, a potential confounding factor, was
not collected. However, at the time of net sales, there was no difference in
malaria prevalence between buyers and non-buyers. The abundance of Anopheles
stephensi, the main vector, did not appear to be affected by ITN. ITN constitute
one of the few feasible options for protection against malaria in chronic
emergencies.

 

Trop Med Int Health  2002 Oct;7(10):846-50 
 
Too poor to pay: charging for insecticide-treated bednets in highland Kenya.
 
Guyatt HL, Ochola SA, Snow RW.
 
Wellcome Trust Research Laboratories/KEMRI, Nairobi, Kenya and Centre for
Tropical Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK.
Division of Malaria Control, Ministry of Health, Nairobi, Kenya.
 
WHO has proposed malaria control as a means to alleviate poverty. One of its
targets includes a 30-fold increase in insecticide-treated nets (ITNs) in the
next 5 years. How this service will be financed remains unclear. In July 2000,
390 homesteads in rural highland Kenya were interviewed on their willingness to
pay for ITNs. The costs to a household of protecting themselves with ITNs were
compared with current household expenditure. Homesteads expressed a willingness
to pay for ITNs, but the amounts offered were not sufficient to cover the costs
of providing this service without donor support to meet the difference.
Furthermore, as most household expenditure was allocated to basic needs these
interventions were 'unaffordable'. The cost of protecting a household with ITNs
would be equivalent to sending three children to primary school for a year. The
aspiration by poor rural homesteads to protect themselves with ITNs is not
compatible with their ability to pay. One option to have an immediate equitable
impact on ITN coverage and break the cycle between malaria and poverty is to
provide this service free of charge.

 

pubmed
 
Parasite  2002 Sep;9(3):255-9 
 
Insecticide mixtures for mosquito net impregnation against malaria vectors.
 
Corbel V, Darriet F, Chandre F, Hougard JM.
 
IRD, 911, avenue Agropolis, BP 64501, 34394 Montpellier, France.
 
Insecticides belonging to the pyrethroid family are the only compounds currently
available for the treatment of mosquito nets. Unfortunately, some malaria vector
species have developed resistance to pyrethroids and the lack of alternative
chemical categories is a great concern. One strategy for resistance management
would be to treat mosquito nets with a mixture associating two insecticides
having different modes of action. This study presents the results obtained with
insecticide mixtures containing several proportions of bifenthrin (a pyrethroid
insecticide) and carbosulfan (a carbamate insecticide). The mixtures were
sprayed on mosquito net samples and their efficacy were tested against a
susceptible strain of Anopheles gambiae, the major malaria vector in Africa. A
significant synergism was observed with a mixture containing 25 mg/m2 of
bifenthrin (half the recommended dosage for treated nets) and 6.25 mg/m2 of
carbosulfan (about 2% of the recommended dosage). The observed mortality was
significantly more than expected in the absence of any interaction (80% vs 41%)
and the knock-down effect was maintained, providing an effective barrier against
susceptible mosquitoes.
 
Parasite  2002 Sep;9(3):247-53 
 
Monitoring the drug-sensitivity of Plasmodium falciparum in coastal towns in 
Madagascar by use of in vitro chemosensitivity and mutation detection tests.
 
Rason MA, Ariey F, Rafidimanantsoa L, Andrianantenaina BH, Sahondra Harisoa JL,
Randrianarivelojosia M.
 
Groupe de Recherche sur le Paludisme, Institut Pasteur de Madagascar, BP 1274,
Antananarivo (101), Republique de Madagascar.
 
The dissemination of mutant and resistant strains of Plasmodium falciparum makes
a considerable contribution to the spread of drug-resistant malaria. Populations
around harbours and airports could be particularly exposed to Plasmodium
isolates introduced with imported cases of malaria. The use of chloroquine as
well as the use of and sulfadoxine/pyrimethamine is currently an effective
method for treating uncomplicated cases of malaria in Madagascar. As part of a
monitoring programme, in vitro methods were used to assess the sensitivity of P.
falciparum isolates in two coastal towns in Madagascar: Mahajanga on the west
coast and Toamasina on the east coast. All of the isolates from both sites were
sensitive to amodiaquine, quinine, pyrimethamine and cycloguanil. All of the
isolates from Mahajanga were sensitive to chloroquine (n = 25; mean IC50 = 22.6
nM, 95% confidence interval: 16.8-28.7 nM), whereas three of the isolates from
Toamasina were resistant to chloroquine (n = 18; mean IC50 = 66.3 nM; 95%
confidence interval: 42.6-90 nM). The frequency of the Pfcrt Thr-76 and the dhfr
Asn-108 mutations was estimated by PCR/RFLP. The 43 P. falciparum isolates
examined, including the three in vitro chloroquine-resistant isolates from
Toamasina were all wild-type (Lys-76). Phenotyping and genotyping studies
suggested that the prevalence of chloroquine- and pyrimethamine-resistant
isolates and of mutant strains of P. falciparum is very low. These results
showed that in vitro test and genotyping of resistance markers approaches could
be successfully used to monitor the emergence of drug-resistant malaria and to
try to alleviate the lack of medical teams able to carry out in vivo test. The
possible hazard/risk associated with imported cases of malaria is discussed.
 
Parasite  2002 Sep;9(3):239-46 
 
Entomological studies carried out in five villages of Senegal
 
Diop A, Molez JF, Konate L, Fontenille D, Gaye O, Diouf M, Diagne M, Faye O.
 
Laboratoire de Paludologie, Institut de Recherche pour le Developpement, IRD, BP
1386, Dakar, Senegal. Email: [email protected]
 
From June 1995 to January 1998, entomological studies carried out in five
villages located in the Delta's Saloum have allowed to better understand the
contribution of An. melas Theobald (1903) to malaria transmission in mangrove
swamp. Among the five villages studied, three of them (Simal, Djilor and
Marlothie) located along the Saloum river, are colonised by An. arabiensis; the
two others (Djifere and Diakhanor) located between the sea and the river, are
colonised by An. melas. During the rainy season and at the begining of the dry
season, An. melas and An. arabiensis are sympatric. The ratio of An. melas/An.
arabiensis increases when we go closer the coast where An. melas becomes quite
exclusive. When An. melas is predominant, endophagy, endophily and anthropophily
are very marked. The parturity rates are lower in An. melas than in An.
arabiensis. In the predominance area of each species, transmission is on the
same level. During the period of sympatry, An. arabiensis is responsible for the
transmission and when it is absent, An. melas carries on. Transmission occurs
from July to March with a maximum at the beginning of the dry season. In the
villages of the mangrove swamp, its prolongation until the middle of the dry
season is due to An. melas.
 
Eur J Clin Microbiol Infect Dis  2002 Sep;21(9):679-81 
 
Prospective Assessment of a New Polymerase Chain Reaction Target 
(STEVOR) for Imported Plasmodium falciparum Malaria.
 
Filisetti D, Bombard S, N'Guiri C, Dahan R, Molet B, Abou-Bacar A, Hansmann Y,
Christmann D, Candolfi E.
 
Institut de Parasitologie et de Pathologie Tropicale, 3 rue Koeberle, 67000
Strasbourg, France, Email: [email protected]
 
The diagnostic value of a polymerase chain reaction (PCR)-based method for
amplifying a new target of repeated genes (STEVOR) in Plasmodium falciparum was
prospectively assessed on samples from 210 febrile patients returning from areas
endemic for malaria. This method is capable of detecting 0.01 parasites in one
microliter of blood. Plasmodium falciparum STEVOR PCR confirmed the results of
the thin- and thick-film direct examination method but identified Plasmodium
falciparum in four patients in whom direct examination was inconclusive at the
species level. Moreover, PCR was positive in two patients with a negative direct
examination. Thus, Plasmodium falciparum STEVOR PCR had 100% sensitivity and
specificity and could be used in selected parasitology laboratories when expert
advice is required.
 
Nature  2002 Oct 3;419(6906):537-42 
 
Analysis of the Plasmodium falciparum proteome by high-accuracy mass
spectrometry.
 
Lasonder E, Ishihama Y, Andersen JS, Vermunt AM, Pain A, Sauerwein RW, Eling WM,
Hall N, Waters AP, Stunnenberg HG, Mann M.
 
Center for Experimental BioInformatics, Department of Biochemistry and Molecular
Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M,
Denmark.
 
The annotated genomes of organisms define a 'blueprint' of their possible gene
products. Post-genome analyses attempt to confirm and modify the annotation and
impose a sense of the spatial, temporal and developmental usage of genetic
information by the organism. Here we describe a large-scale, high-accuracy
(average deviation less than 0.02 Da at 1,000 Da) mass spectrometric proteome
analysis of selected stages of the human malaria parasite Plasmodium falciparum.
The analysis revealed 1,289 proteins of which 714 proteins were identified in
asexual blood stages, 931 in gametocytes and 645 in gametes. The last two groups
provide insights into the biology of the sexual stages of the parasite, and
include conserved, stage-specific, secreted and membrane-associated proteins. A
subset of these proteins contain domains that indicate a role in cell-cell
interactions, and therefore can be evaluated as potential components of a
malaria vaccine formulation. We also report a set of peptides with significant
matches in the parasite genome but not in the protein set predicted by
computational methods.
 
Mini Rev Med Chem  2002 Dec;2(6):573-83 
 
Malaria: new chemotherapeutic peroxide drugs.
 
Borstnik K, Paik IH, Posner GH.
 
Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218, USA.
Email: [email protected]
 
Chemical insights into artemisinin's biological mechanism of action have allowed
rational design of some new trioxane and endoperoxide antimalarial drug
candidates that are efficacious and safe. This review summarizes recent
achievements in this area of peroxide drug development for malaria chemotherapy.
 
Nature  2002 Oct 3;419(6906):534-7 
 
Sequence of Plasmodium falciparum chromosome 12.
 
Hyman RW, Fung E, Conway A, Kurdi O, Mao J, Miranda M, Nakao B, Rowley D, Tamaki T, 
Wang F, Davis RW.
 
Stanford Genome Technology Center, 855 California Avenue, Palo Alto, California
94304 USA, and Departments of Biochemistry and Genetics, Stanford University
Medical College, Stanford University, Stanford, California 94305, USA.
 
The human malaria parasite Plasmodium falciparum is responsible for the death of
more than a million people every year. To stimulate basic research on the
disease, and to promote the development of effective drugs and vaccines against
the parasite, the complete genome of P. falciparum clone 3D7 has been sequenced,
using a chromosome-by-chromosome shotgun strategy. Here we report the nucleotide sequence of the third largest of the parasite's 14 chromosomes, chromosome 12, which comprises about 10% of the 23-megabase genome. As the most (A + T)-rich (80.6%) genome sequenced to date, the P. falciparum genome presented severe problems during the assembly of primary sequence reads. We discuss the methodology that yielded a finished and fully contiguous sequence for chromosome 12. The biological implications of the sequence data are more thoroughly discussed in an accompanying Article (ref. 3).
 
Nature  2002 Oct 3;419(6906):531-4 
 
Sequence of Plasmodium falciparum chromosomes 2, 10, 11 and 14.
 
Gardner MJ, Shallom SJ, Carlton JM, Salzberg SL, Nene V, Shoaibi A, Ciecko A,
Lynn J, Rizzo M, Weaver B, Jarrahi B, Brenner M, Parvizi B, Tallon L, Moazzez A,
Granger D, Fujii C, Hansen C, Pederson J, Feldblyum T, Peterson J, Suh B,
Angiuoli S, Pertea M, Allen J, Selengut J, White O, Cummings LM, Smith HO, Adams
MD, Venter JC, Carucci DJ, Hoffman SL, Fraser CM.
 
The Institute for Genomic Research, 9712 Medical Center Drive, Rockville,
Maryland 20850, USA.
 
The mosquito-borne malaria parasite Plasmodium falciparum kills an estimated
0.7-2.7 million people every year, primarily children in sub-Saharan Africa.
Without effective interventions, a variety of factors-including the spread of
parasites resistant to antimalarial drugs and the increasing insecticide
resistance of mosquitoes-may cause the number of malaria cases to double over
the next two decades. To stimulate basic research and facilitate the development
of new drugs and vaccines, the genome of Plasmodium falciparum clone 3D7 has
been sequenced using a chromosome-by-chromosome shotgun strategy. We report here the nucleotide sequences of chromosomes 10, 11 and 14, and a re-analysis of the chromosome 2 sequence. These chromosomes represent about 35% of the 23-megabase P. falciparum genome.
 
Nature  2002 Oct 3;419(6906):527-31 
 
Sequence of Plasmodium falciparum chromosomes 1, 3-9 and 13.
 
Hall N, Pain A, Berriman M, Churcher C, Harris B, Harris D, Mungall K, Bowman S,
Atkin R, Baker S, Barron A, Brooks K, Buckee CO, Burrows C, Cherevach I,
Chillingworth C, Chillingworth T, Christodoulou Z, Clark L, Clark R, Corton C,
Cronin A, Davies R, Davis P, Dear P, Dearden F, Doggett J, Feltwell T, Goble A,
Goodhead I, Gwilliam R, Hamlin N, Hance Z, Harper D, Hauser H, Hornsby T,
Holroyd S, Horrocks P, Humphray S, Jagels K, James KD, Johnson D, Kerhornou A,
Knights A, Konfortov B, Kyes S, Larke N, Lawson D, Lennard N, Line A, Maddison
M, McLean J, Mooney P, Moule S, Murphy L, Oliver K, Ormond D, Price C, Quail MA,
Rabbinowitsch E, Rajandream MA, Rutter S, Rutherford KM, Sanders M, Simmonds M, 
Seeger K, Sharp S, Smith R, Squares R, Squares S, Stevens K, Taylor K, Tivey A,
Unwin L, Whitehead S, Woodward J, Sulston JE, Craig A, Newbold C, Barrell BG.
 
The Wellcome Trust Sanger Institute, The Wellcome Trust Genome Campus, Hinxton,
Cambridge CB10 1SA, UK.
 
Since the sequencing of the first two chromosomes of the malaria parasite,
Plasmodium falciparum, there has been a concerted effort to sequence and
assemble the entire genome of this organism. Here we report the sequence of
chromosomes 1, 3-9 and 13 of P. falciparum clone 3D7-these chromosomes account
for approximately 55% of the total genome. We describe the methods used to map,
sequence and annotate these chromosomes. By comparing our assemblies with the
optical map, we indicate the completeness of the resulting sequence. During
annotation, we assign Gene Ontology terms to the predicted gene products, and
observe clustering of some malaria-specific terms to specific chromosomes. We
identify a highly conserved sequence element found in the intergenic region of
internal var genes that is not associated with their telomeric counterparts.
 
Nature  2002 Oct 3;419(6906):512-9 
 
Genome sequence and comparative analysis of the model rodent malaria 
parasite Plasmodium yoelii yoelii.
 
Carlton JM, Angiuoli SV, Suh BB, Kooij TW, Pertea M, Silva JC, Ermolaeva MD,
Allen JE, Selengut JD, Koo HL, Peterson JD, Pop M, Kosack DS, Shumway MF,
Bidwell SL, Shallom SJ, Van Aken SE, Riedmuller SB, Feldblyum TV, Cho JK,
Quackenbush J, Sedegah M, Shoaibi A, Cummings LM, Florens L, Yates JR, Raine JD,
Sinden RE, Harris MA, Cunningham DA, Preiser PR, Bergman LW, Vaidya AB, Van Lin
LH, Janse CJ, Waters AP, Smith HO, White OR, Salzberg SL, Venter JC, Fraser CM,
Hoffman SL, Gardner MJ, Carucci DJ.
 
The Institute for Genomic Research, 9712 Medical Center Drive,Rockville,
Maryland 20850, USA.
 
Species of malaria parasite that infect rodents have long been used as models
for malaria disease research. Here we report the whole-genome shotgun sequence
of one species, Plasmodium yoelii yoelii, and comparative studies with the
genome of the human malaria parasite Plasmodium falciparum clone 3D7. A synteny
map of 2,212 P. y. yoelii contiguous DNA sequences (contigs) aligned to 14 P.
falciparum chromosomes reveals marked conservation of gene synteny within the
body of each chromosome. Of about 5,300 P. falciparum genes, more than 3,300 P.
y. yoelii orthologues of predominantly metabolic function were identified. Over
800 copies of a variant antigen gene located in subtelomeric regions were found.
This is the first genome sequence of a model eukaryotic parasite, and it
provides insight into the use of such systems in the modelling of Plasmodium
biology and disease.
 
Nature  2002 Oct 3;419(6906):498-511 
 
Genome sequence of the human malaria parasite Plasmodium falciparum.
 
Gardner MJ, Hall N, Fung E, White O, Berriman M, Hyman RW, Carlton JM, Pain A,
Nelson KE, Bowman S, Paulsen IT, James K, Eisen JA, Rutherford K, Salzberg SL,
Craig A, Kyes S, Chan MS, Nene V, Shallom SJ, Suh B, Peterson J, Angiuoli S,
Pertea M, Allen J, Selengut J, Haft D, Mather MW, Vaidya AB, Martin DM, Fairlamb
AH, Fraunholz MJ, Roos DS, Ralph SA, McFadden GI, Cummings LM, Subramanian GM, 
Mungall C, Venter JC, Carucci DJ, Hoffman SL, Newbold C, Davis RW, Fraser CM,
Barrell B.
 
The Institute for Genomic Research, 9712 Medical Center Drive, Rockville,
Maryland 20850, USA.
 
The parasite Plasmodium falciparum is responsible for hundreds of millions of
cases of malaria, and kills more than one million African children annually.
Here we report an analysis of the genome sequence of P. falciparum clone 3D7.
The 23-megabase nuclear genome consists of 14 chromosomes, encodes about 5,300
genes, and is the most (A + T)-rich genome sequenced to date. Genes involved in
antigenic variation are concentrated in the subtelomeric regions of the
chromosomes. Compared to the genomes of free-living eukaryotic microbes, the
genome of this intracellular parasite encodes fewer enzymes and transporters,
but a large proportion of genes are devoted to immune evasion and host-parasite
interactions. Many nuclear-encoded proteins are targeted to the apicoplast, an
organelle involved in fatty-acid and isoprenoid metabolism. The genome sequence
provides the foundation for future studies of this organism, and is being
exploited in the search for new drugs and vaccines to fight malaria.
 
cases can be made with a RBC-deformability distribution (RBC-DD). Methods. This
paper explores RBC-DDs of healthy individuals and of cells with anomalous
mechanical properties (sickle cell disease, dialysis patients, elliptocytosis,
and cultivated malaria tropica). The distributions were measured with an
automated rheoscope, which uses advanced image analysis techniques to obtain the
deformability index of a large number of individual cells subjected to simple
shear flow. Results. The RBC-DD of healthy volunteers is close to a normal
distribution. In the investigated patients, distributions were markedly
different and yielded significant changes in the mean, in the standard
deviation, or in both. The presence of hypodeformable and hyperdeformable cell
fractions can qualitatively and quantitatively be assessed from the
deformability distribution (DD). In elliptocytosis, cells orient differently
with respect to the streamlines, compared to normal cells. This causes the DD to
be biased. Conclusions. The RBC-DD is a powerful representation to establish
subpopulations with anomalous deformability. Fractions of hypodeformable and
hyperdeformable cells and the standard deviation of the DD are new and excellent
quantitative parameters to assess alterations in RBC deformability.
 
Science  2002 Oct 4;298(5591):213-6 
 
Genetic loci affecting resistance to human malaria parasites in a West African
mosquito vector population.
 
Niare O, Markianos K, Volz J, Oduol F, Toure A, Bagayoko M, Sangare D, Traore
SF, Wang R, Blass C, Dolo G, Bouare M, Kafatos FC, Kruglyak L, Toure YT, Vernick
KD.
 
Department of Medical and Molecular Parasitology, New York University School of
Medicine, 341 East 25th Street, New York, NY 10010, USA.
 
Successful propagation of the malaria parasite Plasmodium falciparum within a
susceptible mosquito vector is a prerequisite for the transmission of malaria. A
field-based genetic analysis of the major human malaria vector, Anopheles
gambiae, has revealed natural factors that reduce the transmission of P.
falciparum. Differences in P. falciparum oocyst numbers between mosquito
isofemale families fed on the same infected blood indicated a large genetic
component affecting resistance to the parasite, and genome-wide scanning in
pedigrees of wild mosquitoes detected segregating resistance alleles. The
apparently high natural frequency of resistance alleles suggests that malaria
parasites (or a similar pathogen) exert a significant selective pressure on
vector populations.
 
Science  2002 Oct 4;298(5591):210-3 
 
Chloroquine resistance in Plasmodium falciparum malaria parasites conferred by 
pfcrt mutations.
 
Sidhu AB, Verdier-Pinard D, Fidock DA.
 
Department of Microbiology and Immunology, Albert Einstein College of Medicine,
Bronx, NY 10461, USA.
 
Plasmodium falciparum chloroquine resistance is a major cause of worldwide
increases in malaria mortality and morbidity. Recent laboratory and clinical
studies have associated chloroquine resistance with point mutations in the gene
pfcrt. However, direct proof of a causal relationship has remained elusive and
most models have posited a multigenic basis of resistance. Here, we provide
conclusive evidence that mutant haplotypes of the pfcrt gene product of Asian,
African, or South American origin confer chloroquine resistance with
characteristic verapamil reversibility and reduced chloroquine accumulation.
pfcrt mutations increased susceptibility to artemisinin and quinine and
minimally affected amodiaquine activity; hence, these antimalarials warrant
further investigation as agents to control chloroquine-resistant falciparum
malaria.
 
Science  2002 Oct 4;298(5591):182-5 
 
Inversions and gene order shuffling in Anopheles gambiae and A. funestus.
 
Sharakhov IV, Serazin AC, Grushko OG, Dana A, Lobo N, Hillenmeyer ME, Westerman R, 
Romero-Severson J, Costantini C, Sagnon N, Collins FH, Besansky NJ.
 
Center for Tropical Disease Research and Training, University of Notre Dame,
Notre Dame, IN 46556-0369, USA.
 
In tropical Africa, Anopheles funestus is one of the three most important
malaria vectors. We physically mapped 157 A. funestus complementary DNAs (cDNAs) to 
the polytene chromosomes of this species. Sequences of the cDNAs were mapped in silico
to the A. gambiae genome as part of a comparative genomic study of synteny, gene
order, and sequence conservation between A. funestus and A. gambiae. These
species are in the same subgenus and diverged about as recently as humans and
chimpanzees. Despite nearly perfect preservation of synteny, we found substantial
shuffling of gene order along corresponding chromosome arms. Since the divergence
of these species, at least 70 chromosomal inversions have been fixed, the highest
rate of rearrangement of any eukaryote studied to date. The high incidence of
paracentric inversions and limited colinearity suggests that locating genes in one
anopheline species based on gene order in another may be limited to closely
related taxa.
 
Science  2002 Oct 4;298(5591):179-81 
 
Evolution of supergene families associated with insecticide resistance.
 
Ranson H, Claudianos C, Ortelli F, Abgrall C, Hemingway J, Sharakhova MV, Unger
MF, Collins FH, Feyereisen R.
 
Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.
 
The emergence of insecticide resistance in the mosquito poses a serious threat
to the efficacy of many malaria control programs. We have searched the Anopheles
gambiae genome for members of the three major enzyme families- the
carboxylesterases, glutathione transferases, and cytochrome P450s-that are
primarily responsible for metabolic resistance to insecticides. A comparative
genomic analysis with Drosophila melanogaster reveals that a considerable
expansion of these supergene families has occurred in the mosquito. Low gene
orthology and little chromosomal synteny paradoxically contrast the easily
identified orthologous groups of genes presumably seeded by common ancestors. In
A. gambiae, the independent expansion of paralogous genes is mainly a
consequence of the formation of clusters among locally duplicated genes. These
expansions may reflect the functional diversification of supergene families
consistent with major differences in the life history and ecology of these
organisms. These data provide a basis for identifying the resistance-associated
enzymes within these families. This will enable the resistance status of
mosquitoes, flies, and possibly other holometabolous insects to be monitored.
The analyses also provide the means for identifying previously unknown molecules
involved in fundamental biological processes such as development.
 
Science  2002 Oct 4;298(5591):172-5 
 
Neuropeptides and peptide hormones in Anopheles gambiae.
 
Riehle MA, Garczynski SF, Crim JW, Hill CA, Brown MR.
 
Department of Entomology, University of Georgia, Athens, GA 30602, USA.
 
The African malaria mosquito, Anopheles gambiae, is specialized for rapid
completion of development and reproduction. A vertebrate blood meal is required
for egg production, and multiple feedings subsequently allow transmission of
malaria parasites, Plasmodium spp. Regulatory peptides from 35 genes annotated
from the A. gambiae genome likely coordinate these and other physiological
processes. Plasmodium parasites may affect actions of newly identified
insulin-like peptides, which coordinate growth and reproduction of its vector,
A. gambiae, as in Drosophila melanogaster, Caenorhabditis elegans, and mammals.
This genomic information provides a basis to expand understanding of hematophagy
and pathogen transmission in this mosquito.
 
Science  2002 Oct 4;298(5591):129-49 
 
The genome sequence of the malaria mosquito Anopheles gambiae.
 
Holt RA, Subramanian GM, Halpern A, Sutton GG, Charlab R, Nusskern DR, Wincker
P, Clark AG, Ribeiro JM, Wides R, Salzberg SL, Loftus B, Yandell M, Majoros WH,
Rusch DB, Lai Z, Kraft CL, Abril JF, Anthouard V, Arensburger P, Atkinson PW,
Baden H, de Berardinis V, Baldwin D, Benes V, Biedler J, Blass C, Bolanos R,
Boscus D, Barnstead M, Cai S, Center A, Chatuverdi K, Christophides GK, Chrystal
MA, Clamp M, Cravchik A, Curwen V, Dana A, Delcher A, Dew I, Evans CA, Flanigan
M, Grundschober-Freimoser A, Friedli L, Gu Z, Guan P, Guigo R, Hillenmeyer ME,
Hladun SL, Hogan JR, Hong YS, Hoover J, Jaillon O, Ke Z, Kodira C, Kokoza E,
Koutsos A, Letunic I, Levitsky A, Liang Y, Lin JJ, Lobo NF, Lopez JR, Malek JA,
McIntosh TC, Meister S, Miller J, Mobarry C, Mongin E, Murphy SD, O'Brochta DA,
Pfannkoch C, Qi R, Regier MA, Remington K, Shao H, Sharakhova MV, Sitter CD,
Shetty J, Smith TJ, Strong R, Sun J, Thomasova D, Ton LQ, Topalis P, Tu Z, Unger
MF, Walenz B, Wang A, Wang J, Wang M, Wang X, Woodford KJ, Wortman JR, Wu M, 
Yao A, Zdobnov EM, Zhang H, Zhao Q, Zhao S, Zhu SC, Zhimulev I, Coluzzi M, della
Torre A, Roth CW, Louis C, Kalush F, Mural RJ, Myers EW, Adams MD, Smith HO,
Broder S, Gardner MJ, Fraser CM, Birney E, Bork P, Brey PT, Venter JC,
Weissenbach J, Kafatos FC, Collins FH, Hoffman SL.
 
Celera Genomics, 45 West Gude Drive, Rockville, MD 20850, USA.
Email: [email protected]
 
Anopheles gambiae is the principal vector of malaria, a disease that afflicts
more than 500 million people and causes more than 1 million deaths each year.
Tenfold shotgun sequence coverage was obtained from the PEST strain of A.
gambiae and assembled into scaffolds that span 278 million base pairs. A total
of 91% of the genome was organized in 303 scaffolds; the largest scaffold was
23.1 million base pairs. There was substantial genetic variation within this
strain, and the apparent existence of two haplotypes of approximately equal
frequency ("dual haplotypes") in a substantial fraction of the genome likely
reflects the outbred nature of the PEST strain. The sequence produced a
conservative inference of more than 400,000 single-nucleotide polymorphisms that
showed a markedly bimodal density distribution. Analysis of the genome sequence
revealed strong evidence for about 14,000 protein-encoding transcripts.
Prominent expansions in specific families of proteins likely involved in cell
adhesion and immunity were noted. An expressed sequence tag analysis of genes
regulated by blood feeding provided insights into the physiological adaptations
of a hematophagous insect.
 
Science  2002 Oct 4;298(5591):124-6 
 
Plasmodium chloroquine resistance and the search for a replacement antimalarial drug.
 
Wellems TE.
 
Laboratory of Malaria and Vector Research, National Institute of Allergy and
Infectious Diseases, Bethesda, MD 20892, USA. Email: [email protected]
 
Genetic and biochemical research is providing new information on the mechanism
of chloroquine resistance. Drug discovery initiatives are finding new leads that
have favorable pharmaceutical properties and efficacy against
chloroquine-resistant malaria.
 
Science  2002 Oct 4;298(5591):122-4 
 
A new global effort to control malaria.
 
Sachs JD.
 
Earth Institute, Columbia University, New York, NY 10027, USA.
 
The time has come to resurrect a worldwide effort to control malaria, following
decades of neglect during which the disease has resurged in many parts of
sub-Saharan Africa and other endemic regions.
 
Science  2002 Oct 4;298(5591):121-2 
 
Malaria--a shadow over Africa.
 
Miller LH, Greenwood B.
 
Laboratory of Malaria and Vector Research, National Institute of Allergy and
Infectious Diseases, Bethesda, MD 20892, USA.
 
Reduction in severe disease and death from falciparum malaria in Africa requires
new, more effective and inexpensive public health measures. The completed
genomes of Plasmodium falciparum and its vector Anopheles gambiae represent a
big step toward the discovery of these needed tools.
 
Science  2002 Oct 4;298(5591):119-21 
 
Malaria control with genetically manipulated insect vectors.
 
Alphey L, Beard CB, Billingsley P, Coetzee M, Crisanti A, Curtis C, Eggleston P,
Godfray C, Hemingway J, Jacobs-Lorena M, James AA, Kafatos FC, Mukwaya LG, Paton M, Powell JR, Schneider W, Scott TW, Sina B, Sinden R, Sinkins S, Spielman A,
Toure Y, Collins FH.
 
Oxford University, UK.
 
At a recent workshop, experts discussed the benefits, risks, and research
priorities associated with using genetically manipulated insects in the control
of vector-borne diseases.
 
Science  2002 Oct 4;298(5591):115-7 
 
Speciation within Anopheles gambiae--the glass is half full.
 
della Torre A, Costantini C, Besansky NJ, Caccone A, Petrarca V, Powell JR,
Coluzzi M.
 
Parasitology Unit, Department of Public Health, University of Rome "La
Sapienza," P.le Aldo Moro 5, 00185 Rome, Italy. Email: [email protected]
 
Restrictions to gene flow among molecular forms of the mosquito Anopheles
gambiae sensu stricto reveal an ongoing speciation process affecting the
epidemiology of malaria in sub-Saharan Africa.
 
Science  2002 Oct 4;298(5591):96-7 
 
An overview of insecticide resistance.
 
Hemingway J, Field L, Vontas J.
 
Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK.
 
Insecticide resistance poses a serious threat to current malaria control
efforts. The Anopheles gambiae genome will enable identification of new
resistance genes and will provide new molecular targets for the design of more
effective insecticides.
 
Science  2002 Oct 4;298(5591):79 
 
The mosquito genome--a breakthrough for public health.
 
Morel CM, Toure YT, Dobrokhotov B, Oduola AM.
 
Special Programme for Research and Training in Tropical Diseases (TDR), World
Health Organization, 20 Avenue Appia, CH-1211 Geneva 27, Switzerland.
Email: [email protected]
 
 
The Anopheles gambiae genome sequence will accelerate identification of new
insect vector target genes leading to improved strategies for malaria control.
 
Science  2002 Oct 4;298(5591):33-4 
 
Malaria research. Parasite genome sequenced, scrutinized.
 
Pennisi E.
 
This week, an almost complete DNA sequence of Plasmodium falciparum--one of the
parasites that causes malaria--appears in Nature, and on page 129 of this issue
of Science, other researchers report the DNA sequence of Anopheles gambiae, one
of the mosquitoes that transmits P. falciparum to humans. Together with the
human genome sequence, researchers now have in hand the genetic blueprints for
the parasite, its vector, and its victim.
 
Science  2002 Oct 3; [epub ahead of print] 
 
A Polytene Chromosome Analysis of the Anopheles gambiae Species Complex.
 
Coluzzi M, Sabatini A, Della Torre A, Di Deco MA, Petrarca V.
 
Dipartimento di Scienze di Sanita Pubblica and Istituto Pasteur-Cenci
Bolognetti, Universita "La Sapienza," Rome, Italy., Dipartimento di Genetica e
Biologia Molecolare, Universita "La Sapienza," Rome, Italy.
 
Field collected specimens of all known taxa in the Anopheles gambiae complex
were analyzed on the basis of chromosome inversions with reference to a standard
polytene chromosome map. The phylogenetic relationship among the seven described
species in the complex could be inferred from the distribution of fixed
inversions. Nonrandom patterns of inversion distribution were observed and,
particularly on chromosome arm 2R, provided evidence for genetically distinct
populations in A. gambiae, A. arabiensis, and A. melas. In A. gambiae from Mali,
stable genetic differentiation was observed even in populations living in the
same region, suggesting a process of incipient speciation. The possible role of
chromosome differentiation in speciation of the A. gambiae complex and in the
emergence of distinct chromosomal forms within the nominal species is discussed
in relation to human malaria.
 
Clin Microbiol Rev  2002 Oct;15(4):595-612 
 
History of human parasitology.
 
Cox FE.
 
Department of Infectious and Tropical Diseases, London School of Hygiene and
Tropical Medicine, London WC1E 7HT, United Kingdom.
 
Humans are hosts to nearly 300 species of parasitic worms and over 70 species of
protozoa, some derived from our primate ancestors and some acquired from the
animals we have domesticated or come in contact with during our relatively short
history on Earth. Our knowledge of parasitic infections extends into antiquity,
and descriptions of parasites and parasitic infections are found in the earliest
writings and have been confirmed by the finding of parasites in archaeological
material. The systematic study of parasites began with the rejection of the
theory of spontaneous generation and the promulgation of the germ theory.
Thereafter, the history of human parasitology proceeded along two lines, the
discovery of a parasite and its subsequent association with disease and the
recognition of a disease and the subsequent discovery that it was caused by a
parasite. This review is concerned with the major helminth and protozoan
infections of humans: ascariasis, trichinosis, strongyloidiasis, dracunculiasis,
lymphatic filariasis, loasis, onchocerciasis, schistosomiasis, cestodiasis,
paragonimiasis, clonorchiasis, opisthorchiasis, amoebiasis, giardiasis, African
trypanosomiasis, South American trypanosomiasis, leishmaniasis, malaria,
toxoplasmosis, cryptosporidiosis, cyclosporiasis, and microsporidiosis.
 
Clin Microbiol Rev  2002 Oct;15(4):564-94 
 
Evolutionary and historical aspects of the burden of malaria.
 
Carter R, Mendis KN.
 
University of Edinburgh, Division of Biological Sciences, ICAPB, Ashworth
Laboratories, Edinburgh EH9 3JT, United Kingdom. Roll Back Malaria Project,
World Health Organization, Geneva 27, Switzerland.
 
Malaria is among the oldest of diseases. In one form or another, it has infected
and affected our ancestors since long before the origin of the human line.
During our recent evolution, its influence has probably been greater than that
of any other infectious agent. Here we attempt to trace the forms and impacts of
malaria from a distant past through historical times to the present. In the last
sections, we review the current burdens of malaria across the world and discuss
present-day approaches to its management. Only by following, or attempting to
follow, malaria throughout its evolution and history can we understand its
character and so be better prepared for our future management of this ancient
ill.
 
Am J Trop Med Hyg  2002 Jul;67(1):8-16 
 
Alterations in Plasmodium falciparum genotypes during sequential infections
suggest the presence of strain specific immunity.
 
Eisen DP, Saul A, Fryauff DJ, Reeder JC, Coppel RL.
 
Department of Microbiology, Monash University, Clayton, Victoria, Australia.
 
Many of the asexual stage Plasmodium falciparum proteins that are the targets of
host protective responses are markedly polymorphic. The full repertoire of
diversity is not defined for any antigen. Most studies have focused on the genes
encoding merozoite surface proteins 1 and 2 (MSP1, MSP2). We explored the extent
of diversity of some of the less studied merozoite surface antigens and analyzed
the degree of complexity of malaria field isolates by deriving nucleotide
sequences of several antigens. We have determined the genotype of apical
membrane antigen 1 (AMA1) in a group of 30 field samples, collected over 29
months, from individuals living in an area of intense malaria transmission in
Irian Jaya, identifying 14 different alleles. AMA1 genotyping was combined with
previously determined MSP2 typing. AMA1 had the greatest power in distinguishing
between isolates but methodological problems, especially when mixed infections
are present, suggest it is not an ideal typing target. MSP1, MSP3, and
glutamate-rich protein genotypes were also determined from a smaller group of
samples, and all results were combined to derive an extended antigenic
haplotype. Within this subset of 10 patients, nine different genotypes could be
discerned; however, five patients were all infected with the same strain. This
strain was present in individuals from two separate villages and was still
present 12 months later. This strain was predominant at the first time point but
had disappeared at the fourth time point. This significant change in malaria
genotypes could be due to strain-specific immunity developing in this
population.
 
 
Am J Trop Med Hyg  2002 Jul;67(1):64-6 
 
Short report: Molecular evaluation of the efficacy of chloroquine treatment of
uncomplicated Plasmodium falciparum malaria in East Timor.
 
Chen N, Baker J, Ezard N, Burns M, Edstein MD, Cheng Q.
 
Australian Army Malaria Institute, Brisbane, Queensland, Australia.
 
The efficacy of chloroquine treatment of uncomplicated Plasmodium falciparum
malaria in East Timor was investigated via molecular tools. Genotyping of the
polymorphic markers msp1 and msp2 was performed to investigate the number and
type of parasite alleles in pre- and posttreatment blood samples collected from
48 patients. Patients were infected with a minimum of 8 msp1 and 14 msp2 allelic
types of parasite, and 43% of the patients had more than one allelic type before
treatment. The genotyping also revealed that 66.7% of the patients were infected
with at least one identical allelic type of parasite before and after treatment
and therefore were likely to have experienced recrudescence. All parasites in
pre- and posttreatment blood samples carried the K76T mutation in pfcrt,
regardless of the clinical response to chloroquine. The sequence polymorphism
patterns in pfcrt in the majority of parasites examined were identical to those
observed in Bougainville, Papua New Guinea.
 
Am J Trop Med Hyg  2002 Jul;67(1):61-3 
 
Ocular lesions associated with malaria in children in Mali.
 
Schemann JF, Doumbo O, Malvy D, Traore L, Kone A, Sidibe T, Keita M.
 
Institute of African Tropical Ophthalmology, Bamako, Mali.
Email: [email protected]
 
This study sought to estimate the frequency of ocular complications in malaria
and its prognostic value in Mali. A total of 140 children (aged 6 months to 9
years) with severe malaria (105 with cerebral malaria, 35 without neurological
complications) were compared with 34 children with mild malaria and 82 children
with nonmalarial fever. Ocular lesions were rare in the mild malaria group
(5.8%). Retinal hemorrhages occurred in 11.8% of the children in the severe
noncerebral malaria group. Cerebral malaria was associated with retinal
hemorrhages (22.9%) and retinal edema (10.5%). No association was found between
ocular signs such as retinal hemorrhages or retinal edema and mortality.
Exudates, papilledema, and the presence of cottonwool spots were associated with
an increased risk of death. Coma score and convulsions were significantly
associated with death but not with ocular signs. The presence of retinal signs
in a child in a malaria-endemic area may signal a case of severe malaria.
 
Am J Trop Med Hyg  2002 Jul;67(1):54-60 
 
The effects of antimalarial drugs on ventricular repolarization.
 
Touze JE, Heno P, Fourcade L, Deharo JC, Thomas G, Bohan S, Paule P, Riviere P,
Kouassi E, Buguet A.
 
Service de Cardiologie, Hospital d'Instruction des Armees, Marseille, France.
 
Cardiotoxicity has become a major concern during treatment with antimalarial
drugs. Lengthening of the QTc and severe cardiac arrhythmia have been observed,
particularly after treatment with halofantrine for chloroquine-resistant
Plasmodium falciparum malaria. The purpose of this prospective study was to
evaluate whether antimalarial agents alter dispersion of the QTc and ventricular
repolarization dynamicity. Sixty patients with uncomplicated falciparum malaria
were randomly allocated in four groups of 15 patients and treated with quinine,
mefloquine, artemether, or halofantrine at recommended doses. Patients in
treatment groups were compared with a group including 15 healthy controls with
no history of malaria and/or febrile illness within the last month. QTc
dispersion was measured on surface electrocardiograms. Repolarization dynamicity
was analyzed from Holter recordings, which allow automatic beat-to-beat
measurement of QT and RR intervals. Plasma drug concentration was determined by
reversed-phase high-performance liquid chromatography. No change in QTc
dispersion was observed after treatment with quinine, mefloquine, or artemether.
Treatment with halofantrine was followed by a significant increase in QTc
dispersion at 9 hours (P < 0.0001) and 24 hours (P < 0.01). Assessment of QT
heart rate variability by QT/RR nychtohemeral regression slope demonstrated no
significant difference between the artemether (mean +/- SEM = 0.170 +/- 0.048),
mefloquine (0.145 +/- 0.044), and the control groups (0.172 +/- 0.039). A
significant decrease in the Q-eT/RR slope was observed in the quinine group
compared with the control and artemether groups (0.135 +/- 0.057; P < 0.04).
With halofantrine, a significant increase in the QT/RR regression slope (0.289
+/- 0.118) was observed (P < 0.0002). QTc interval, QT dispersion, and QT
regression slope were significantly correlated with halofantrine and quinine
plasma concentration. Mefloquine and artemether did not alter ventricular
repolarization. Quinine induced a significant decrease in QT/RR slope of the
same order of magnitude as those previously observed with quinidine. Both QTc
dispersion and QT/RR slope were significantly modified by halofantrine. These
repolarization changes were related to a class-III antiarrhythmic drug effect
and may explain the occurrence of ventricular arrhythmia and/or sudden deaths
reported after halofantrine intake.
 
Am J Trop Med Hyg  2002 Jul;67(1):44-53 
 
Malaria and human immunodeficiency virus infection as risk factors for anemia
in infants in Kisumu, western Kenya.
 
van Eijk AM, Ayisi JG, Ter Kuile FO, Misore AO, Otieno JA, Kolczak MS, Kager PA,
Steketee RW, Nahlen BL.
 
Kenya Medical Research Institute, Center for Vector Biology and Control
Research, Kisumu. Emasil: [email protected]
 
The role of maternal and pediatric infection with human immunodeficiency virus
type 1 (HIV-1) and malaria as risk factors for anemia was determined in a birth
cohort of infants born to mothers participating in a study of the interaction
between placental malaria and HIV infection, in Kisumu, Kenya. Between June 1996
and April 2000, 661 infants born to 467 HIV-seropositive and 194
HIV-seronegative mothers were monitored monthly from birth. At each visit a
questionnaire was completed and a blood sample was collected for the
determination of hemoglobin levels and detection of malaria and HIV. Anemia was
common and increased from 13.6% at one month to 75% at six months and remained
high throughout the second half of infancy. Placental malaria, infant malaria, and HIV
infection of the infant were all associated with infant anemia in a multivariate model,
adjusting for other co-variates found to be associated with infant anemia. The
HIV-infected infants with malaria parasitemia had lower mean hemoglobin levels
compared with HIV-uninfected infants, or HIV-infected infants
without malaria, suggesting that HIV-infected infants are particularly
vulnerable to the adverse consequences of malaria at this age. Early detection
and prompt treatment of infant malaria and treatment of anemia as part of the
study protocol failed to prevent most of the infants from becoming anemic.
Although not proven effective in this study, micronutrient supplementation
should be prospectively assessed in HIV-infected infants as a means of
preventing anemia.
 
Am J Trop Med Hyg  2002 Jul;67(1):39-43 
 
In vitro activity of tafenoquine alone and in combination with artemisinin
against Plasmodium falciparum.
 
Ramharter M, Noedl H, Thimasarn K, Wiedermann G, Wernsdorfer G, Wernsdorfer WH.
 
Department of Specific Prophylaxis and Tropical Medicine, Institute of
Pathophysiology, University of Vienna, Austria.
 
Emergence and spread of drug-resistant falciparum malaria has created an urgent
demand for alternative therapeutic agents. This study was conducted to assess
the in vitro blood schizontocidal activity of tafenoquine, the most advanced
candidate drug of the 8-aminoquinolines, and of its 1:1 combination with
artemisinin in fresh isolates of Plasmodium falciparum in an area with
multi-drug resistance, measuring the inhibition of schizont maturation. In 43
successfully tested parasite isolates, the mean effective concentrations (ECs)
of tafenoquine were 209 nmol/L for the EC50, and 1,414 nmol/L for the EC90.
Tafenoquine showed no significant activity relationships with mefloquine,
artemisinin, and chloroquine. With quinine, a highly significant activity
relationship was observed at the EC50, but not at the EC90. The EC50, and EC90
of the tafenoquine-artemisinin combination were 15.9 nmol/L and 84.3 nmol/L. The
combination was synergistic. Tafenoquine appears to be a promising candidate for
treating multidrug-resistant falciparum malaria, especially in combination with
artemisinin derivatives.
 
Am J Trop Med Hyg  2002 Jul;67(1):32-8 
 
Influence of host and larval habitat distribution on the abundance of African
malaria vectors in western Kenya.
 
Minakawa N, Seda P, Yan G.
 
Department of Biological Sciences, State University of New York, Buffalo 14260,
USA.
 
The abundance of anopheline mosquitoes varies substantially among houses within
the same villages. Anopheles gambiae sensu stricto is highly anthropophilic, and
Anopheles arabiensis is zoophilic; thus, it is often hypothesized that the
abundance of An. gambiae and An. arabiensis in a house is associated with the
distribution of livestock and humans. In this paper we examined the influence of
livestock and human host availability on the distribution and abundance of
malaria vectors in the basin region of Lake Victoria in western Kenya. Larvae
and adults of An. gambiae, An. arabiensis and Anopheles funestus were collected
in the beginning and the end of the rainy season in 1999. Anopheles gambiae was
the predominant species in both larval and adult samples. Multiple regression
analyses found that the ratio of distance between houses and larval habitats to
distance between cowsheds and larval habitats had a significant and negative
association with the relative abundance of An. gambiae larvae for both sampling
periods. The ratio of human density to cow density was positively correlated
with the relative abundance of An. gambiae larvae in the late rainy period. For
the adult samples, distance from a house to its nearest larval habitats was the
only variable that showed a significant correlation with the An. gambiae density
in houses in both sample periods. More than 90% of anopheline adults were found
in the houses within 300 meters from the nearest larval habitats. Anopheline
mosquito density was not correlated to the density of cows or humans, or the
distance to cowsheds from houses. These results suggest that livestock and human
host availability affect the relative abundance of An. gambiae larvae in aquatic
habitats, but the distribution of anopheline adults in houses is determined by
the distance from houses to larval habitats.
 
Am J Trop Med Hyg  2002 Jul;67(1):28-31 
 
Treatment of children with Plasmodium falciparum malaria with chloroquine
in Guinea-Bissau.
 
Kofoed PE, Lopez F, Johansson P, Sandstrom A, Hedegaard K, Aaby P, Rombo L.
 
Projecto de Saude de Bandim, Bissau, Guinea-Bissau. Email: [email protected]
 
Children with symptomatic malaria in Bissau, Guinea-Bissau were randomly
assigned to treatment with a 25 mg/kg total dose of chloroquine as recommended
by the National Malaria Program or with a higher total dose of 50 mg/kg.
Sixty-seven and 62 children, respectively, completed the treatment and were then
followed once a week for five weeks. Treatment with a dose of 50 mg/kg was
significantly more effective than treatment with 25 mg/kg in preventing
recrudescence. The cumulative relative risk (95% confidence interval) of having
parasitemia in the low-dose group during follow-up was 0.20 (0.08-0.52) on day
21, 0.38 (0.17-0.86) on day 28, and 0.48 (0.23-0.98) on day 35. Few adverse
events were reported, although more children complained of vomiting and diarrhea
on day 2 in the high-dose group compared with those in the low-dose group.
However, this difference was not statistically significant. We conclude that a
dose of 50 mg/kg of chloroquine could be recommended for treatment of Plasmodium
falciparum malaria in Bissau. To minimize the risk of side effects, this higher dose should
be given divided into two daily doses over a three-day period.
 
Am J Trop Med Hyg  2002 Jul;67(1):17-23 
 
The safety and efficacy of sulfadoxine-pyrimethamine, amodiaquine, and their
combination in the treatment of uncomplicated Plasmodium falciparum malaria.
 
Schellenberg D, Kahigwa E, Drakeley C, Malende A, Wigayi J, Msokame C, Aponte
JJ, Tanner M, Mshinda H, Menendez C, Alonso PL.
 
Unidad de Epidemiologia, Hospital Clinic, Barcelona, Spain.
 
The safety and efficacy of amodiaquine (AQ), sulfadoxine-pyrimethamine (SP), and
coadministered AQ+SP was assessed in 351 Tanzanian children (age range, 6-59
months) with uncomplicated Plasmodium falciparum malaria. This open, randomized
study followed the 28-day World Health Organization (WHO) protocol and evaluated
safety using clinical and laboratory parameters. Children receiving SP were more
likely to vomit during follow-up (32% vs. 17%: P = 0.03), and SP alone resulted
in prolonged fever clearance times. Although Day 7 and Day 14 clinical and
parasitological cure rates were similar, by Day 28 45% of children treated with
AQ demonstrated R1 resistance and 27.5% were clinical failures compared with 25%
and 6.3%, respectively, for SP alone. Coadministered AQ+SP was safe, combined
the greater clinical (96.2%) and parasitological (64.2%) efficacy of SP with the
more rapid symptom resolution of AQ, and reduced the incidence of gametocytemia
during follow-up (AQ+SP 12.6% vs. SP 29.9%; P = 0.001). The level of R1
resistance to SP may herald a rapid decline in its efficacy as SP drug pressure
increases. Coadministration of AQ+SP may delay this.
 
Indian J Med Res  2002 May;115:194-200 
 
Ruby-eye, a new autosomal mutant in the malaria mosquito, Anopheles 
stephensi Liston.
 
Madhyastha AD, Shetty NJ.
 
Centre for Applied Genetics, Bangalore University, Bangalore, India.
 
BACKGROUND & OBJECTIVES: Anopheles stephensi, an important vector of malaria
continues to be distributed widely in the Indian subcontinent. This vector
species has developed resistance for various insecticides. Therefore, it is
desirable to develop alternate strategy, which does not involve resistance. In
order to develop such strategy, it is mandatory that genetic studies of
concerned vector species should be established. This paper describes the
isolation and genetic studies of an eye colour mutant, ruby-eye (ru), and
linkage studies involving another autosomal recessive mutant greyish brown larva
(grb ru) in A. stephensi. METHODS: The stocks of mutants ruby-eye (ru), greyish
brown (grb ru) and wild type mosquitoes were maintained in the laboratory.
Crosses were made between the wild type and mutant to determine the mode of
inheritance of ruby-eye. For linkage studies crosses were made between the
mutant ruby-eye and another autosomal recessive mutant greyish brown larva. The
percentage cross over was calculated for the genes linkage relationship for ru
and grb ru. RESULTS: Results of crosses between mutant and wild type show that
the inheritance of ruby-eye in A. stephensi is monofactorial in nature. The ru
allele is recessive to wild type and is autosomal. The linkage studies showed no
linkage between grb and ru. INTERPRETATION & CONCLUSION: The mutant ru
represents an excellent marker for A. stephensi as it expresses in all the life
stages with complete penetrance and high viability. This mutant can be used
extensively to conduct basic and applied research.
 
Pediatrics  2002 Oct;110(4):e48 
 
Stunting may determine the severity of malaria-associated anemia in African
children.
 
Verhoef H, West CE, Veenemans J, Beguin Y, Kok FJ.
 
Division of Human Nutrition and Epidemiology, Wageningen University, The
Netherlands. .
 
OBJECTIVE: Evidence from previous studies that malnourished children are
protected against malaria is controversial. In individuals repeatedly exposed to
malaria, immunity may develop first against severe disease, then against
pyrogens, and last, against parasites. If this is true, this would suggest that
reduced immune function that may exist in stunted children exacerbates the
severity of malarial signs and symptoms, rather than the occurrence of
parasitemia. On the other hand, several studies have suggested that malnourished
children are protected to some degree against malaria. Our aim was to evaluate
whether observational data support the hypothesis that nutritional inadequacies
that cause stunting modify the associations between malaria and hematologic
indicators such as hemoglobin concentration and serum concentrations of
C-reactive protein and soluble transferrin receptor (sTfR). We showed earlier
that increased serum concentrations of these receptors in asymptomatic malaria
may be explained, at least in part, by increased erythropoiesis to compensate
for malaria-induced hemolysis. METHODOLOGY: Community-based cluster survey 
among Kenyan children aged 2 to 36 months asymptomatic for malaria or anemia
(n = 318). RESULTS: When adjusted for age and wasting, the malaria-associated
decrease in mean hemoglobin concentration was 8.5 g/L and 15.8 g/L in nonstunted
and stunted children, respectively. The malaria-associated increase in geometric
mean serum concentrations of sTfR was 1.1-fold and 1.8-fold in nonstunted and
stunted children, respectively. The malaria-associated increase in geometric
mean serum concentrations of C-reactive protein was 1.4-fold and 2.3-fold in
nonstunted and stunted children, respectively. Thus, children with malaria and
those who were stunted suffered from more severe anemia and had higher serum
concentrations of C-reactive protein and sTfR than would be expected from the
combined effect of the 2 working independently. CONCLUSIONS: Our results are
consistent with the notion that the nutritional inadequacies causing stunting
also impair host immunity, thus increasing the degree to which malaria is
associated with decreased concentrations of hemoglobin, with increased
inflammation, and with increased iron demand in developing erythroblasts.
Increased intake of micronutrients may not only reduce stunting and nutritional
anemia, but also reduce malaria-associated anemia.
 
Trop Med Int Health  2002 Oct;7(10):858-864 
 
Artemisinin or chloroquine for blood stage Plasmodium vivax malaria
in Vietnam.
 
Phan GT, De Vries PJ, Tran BQ, Le HQ, Nguyen NV, Nguyen TV, Heisterkamp SH,
Kager PA.
 
Division of Infectious Diseases, Tropical Medicine and AIDS, Academic Medical
Center, Amsterdam, the Netherlands. Tropical Diseases Clinical Research Center,
Cho Ray Hospital, Ho Chi Minh City, Vietnam. Binh Thuan Provincial Malaria
Station, Phan Thiet, Vietnam. Mepu Health Post, Duc Linh District, Vietnam.
Department of Clinical Epidemiology and Biostatistics, Academic Medical Center,
Amsterdam, the Netherlands.
 
Chloroquine-resistant Plasmodium vivax has not yet occurred in Vietnam. The
efficacy of artemisinin for P. vivax was not established. We conducted a
double-blind randomized study involving 240 inpatients with P. vivax malaria who
received artemisinin (40 mg/kg over 3 days) plus placebo chloroquine (Art) or
chloroquine (25 mg/kg over 3 days) plus placebo artemisinin (Chl). Patients were
followed up with weekly blood smears for 28 days. In each group 113 cases were
analysed. All patients recovered rapidly. The median (range) parasite clearance
time of regimen Art was 24 h (8-72) and of Chl 24 h (8-64; P = 0.3). Parasites
reappeared in two cases in each group on day 14, in eight cases in each group
(7%) on day 16 and in 25 (23%) and 18 (16%) cases, respectively, at the end of
4-week follow-up (P = 0.3). The population parasite clearance curve followed a
mono-exponential decline. The parasite reduction ratio per 48 h reproduction
cycle was 2.3 x 104 for both regimens. We conclude that artemisinin and
chloroquine are equally effective in the treatment of P. vivax infections in
Vietnam. Reappearance of parasites before day 16 (7%) suggests the emergence of
chloroquine resistance. Three days of artemisinin monotherapy does not prevent
recrudescence.
 
Trop Med Int Health  2002 Oct;7(10):851-857 
 
Forecasting malaria incidence from historical morbidity patterns in
epidemic-prone areas of Ethiopia: a simple seasonal adjustment method
performs best.
 
Abeku TA, De Vlas SJ, Borsboom G, Teklehaimanot A, Kebede A, Olana D, Van
Oortmarssen GJ, Habbema JD.
 
Department of Public Health, Erasmus MC, University Medical Center Rotterdam,
The Netherlands. Department of Infectious and Tropical Diseases, London School
of Hygiene and Tropical Medicine, UK. Disease Prevention and Control Department,
Ministry of Health, Addis Ababa, Ethiopia. Center for International Development,
Harvard University, Cambridge, USA. Amhara Regional State Health Bureau, Bahir
Dar, Ethiopia. Oromiya Regional State Health Bureau, Addis Ababa, Ethiopia.
 
The aim of this study was to assess the accuracy of different methods of
forecasting malaria incidence from historical morbidity patterns in areas with
unstable transmission. We tested five methods using incidence data reported from
health facilities in 20 areas in central and north-western Ethiopia. The
accuracy of each method was determined by calculating errors resulting from the
difference between observed incidence and corresponding forecasts obtained for
prediction intervals of up to 12 months. Simple seasonal adjustment methods
outperformed a statistically more advanced autoregressive integrated moving
average method. In particular, a seasonal adjustment method that uses mean
deviation of the last three observations from expected seasonal values
consistently produced the best forecasts. Using 3 years' observation to generate
forecasts with this method gave lower errors than shorter or longer periods.
Incidence during the rainy months of June-August was the most predictable with
this method. Forecasts for the normally dry months, particularly
December-February, were less accurate. The study shows the limitations of
forecasting incidence from historical morbidity patterns alone, and indicates
the need for improved epidemic early warning by incorporating external
predictors such as meteorological factors.
 
Trop Med Int Health  2002 Oct;7(10):823-830 
 
Risk factors for presentation to hospital with severe anaemia in Tanzanian
children: a case-control study.
 
Kahigwa E, Schellenberg D, Sanz S, Aponte JJ, Wigayi J, Mshinda H, Alonso P,
Menendez C.
 
Ifakara Health Research and Development Centre, Ifakara, Tanzania. St Francis
Designated District Hospital, Ifakara, Tanzania. Unidad de Epidemiologia y
Bioestadistica, Institut d'Investigacions Biomediques August Pi i Sunyer
(IDIBAPS), Hospital Clinic, Barcelona, Spain.
 
In malaria endemic areas anaemia is a usually silent condition that nevertheless
places a considerable burden on health services. Cases of severe anaemia often
require hospitalization and blood transfusions. The objective of this study was
to assess risk factors for admission with anaemia to facilitate the design of
anaemia control programmes. We conducted a prospective case-control study of
children aged 2-59 months admitted to a district hospital in southern Tanzania.
There were 216 cases of severe anaemia [packed cell volume (PCV) < 25%] and 234
age-matched controls (PCV >/= 25%). Most cases [55.6% (n = 120)] were < 1 year
of age. Anaemia was significantly associated with the educational level of
parents, type of accommodation, health-seeking behaviour, the child's
nutritional status and recent and current medical history. Of these, the single
most important factor was Plasmodium falciparum parasitaemia [OR 4.3, 95%
confidence interval (CI) 2.9-6.5, P < 0.001]. Multivariate analysis showed that
increased recent health expenditure [OR 2.2 (95% CI 1.3-3.9), P = 0.005],
malnutrition [OR 2.4 (95%CI 1.3-4.3), P < 0.001], living > 10 km from the
hospital [OR 3.0 (95% CI 1.9-4.9), P < 0.001], a history of previous blood
transfusion [OR 3.8 (95% CI 1.7-9.1), P < 0.001] and P. falciparum parasitaemia
[OR 9.5 (95% CI 4.3-21.3), P < 0.001] were independently related to risk of
being admitted with anaemia. These findings are considered in terms of the
pathophysiological pathway leading to anaemia. The concentration of anaemia in
infants and problems of access to health services and adequate case management
underline the need for targeted preventive strategies for anaemia control.
 
J Infect Dis  2002 Oct 15;186(8):1194-7 
 
Dichotomous Effects of Plasmodium falciparum Antigens on Expression of Human Immunodeficiency Virus (HIV) Coreceptors and on Infectability of CD4 Cells by HIV.
 
Moriuchi M, Moriuchi H, Mon HM, Kanbara H.
 
Division of Medical Virology, Department of Molecular Microbiology and
Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki
852-8501, Japan. Email: [email protected]
 
Many microbial coinfections accelerate the progression of human immunodeficiency
virus (HIV) disease. Coinfections of Plasmodium falciparum malaria and HIV-1 are
common; however, past studies of the effects of P. falciparum malaria on HIV-1
infection have shown little effect. The present study found that P. falciparum
antigens (PF-Ags) variably regulate the expression of HIV-1 coreceptors and
modulate the infectability of CD4 cells by HIV-1. Shortly after PF-Ag
stimulation, CCR5 expression was down-regulated, but CXCR4 expression was
modestly up-regulated. Subsequently, CCR5 expression on CD4 cells was induced.
Infectability of PF-Ag-stimulated peripheral blood mononuclear cells (PBMC) by
R5 HIV-1 was decreased, regardless of the duration of PF-Ag stimulation or CCR5
expression levels. In contrast, X4 HIV-1 replication was enhanced briefly in
PBMC stimulated with PF-Ags but was inhibited with longer stimulation. Decreased
HIV-1 infectability resulted, in part, from endogenous production of
interferon-gamma. These results may explain why malaria previously did not
appear to accelerate HIV-1 disease progression.
 
Lancet  2002 Sep 21;360(9337):908 
 
Intermittent administration of iron and sulfadoxine-pyrimethamine to control
anaemia in Kenyan children: a randomised controlled trial.
 
Verhoef H, West C, Nzyuko S, de Vogel S, van der Valk R, Wanga M, Kuijsten A,
Veenemans J, Kok F.
 
Division of Human Nutrition and Epidemiology, Wageningen University, Wageningen,
Netherlands
 
Background Iron supplementation is recommended for children at high risk of
anaemia, but its benefits may not outweigh the associated risk of malaria in
areas of seasonal transmission. We investigated the effect on haemoglobin
concentrations of intermittent administration of iron supplements and
sulfadoxine-pyrimethamine in symptom-free children under intense health
surveillance.Methods In a trial of two by two factorial design, 328 anaemic
Kenyan children were randomly assigned either iron or placebo and
sulfadoxine-pyrimethamine or placebo (82 to each group). Primary outcomes were
haemological indicators of iron status and inflammation at the end of the
follow-up, and occurrence of malaria attacks. Morbidity surveillance consisted
of medical examinations every 4 weeks, continuous passive case detection, and
visits twice a week to community health-workers. Analyses were by intention to
treat.Findings After 12 weeks, the groups assigned iron plus
sulfadoxine-pyrimethamine, iron alone, or sulfadoxine-pyrimethamine alone had
higher haemoglobin concentrations than the group assigned placebo (treatment
effect adjusted for prognostic factors at baseline: 11.1 g/L [95% CI 7.5 to
14.7]; 10.7 g/L [7.1 to 14.3]; and 3.1 g/L [-0.5 to 6.7]). Administration of
iron plus sulfadoxine-pyrimethamine also lowered the proportion with anaemia
from 100% at baseline to 36% at 12 weeks, and of iron deficiency from 66% at
baseline to 8% at 12 weeks. Survival analysis showed no evidence of
substantially increased risk of malaria after iron
supplementation.Interpretation Iron supplementation gives substantial health
benefits, which may outweigh possible inherent risks caused by malaria. A larger
study than ours is needed to assess benefits and risks of intermittent
administration of sulfadoxine-pyrimethamine in reducing the incidence of malaria
attacks in areas of seasonal malaria transmission.
 
Mol Microbiol  2002 Sep;45(6):1473-84 
 
A malaria scavenger receptor-like protein essential for parasite development.
 
Claudianos C, Dessens JT, Trueman HE, Arai M, Mendoza J, Butcher GA, Crompton T,
Sinden RE.
 
Malaria parasites suffer severe losses in the mosquito as they cross the midgut,
haemolymph and salivary gland tissues, in part caused by immune responses of the
insect. The parasite compensates for these losses by multiplying during the
oocyst stage to form the infectious sporozoites. Upon human infection, malaria
parasites are again attenuated by sustained immune attack. Here, we report a
single copy gene that is highly conserved amongst Plasmodium species that
encodes a secreted protein named PxSR. The predicted protein is composed of a
unique combination of metazoan protein domains that have been previously
associated with immune recognition/activation and lipid/protein adhesion
interactions at the cell surface, namely: (i) scavenger receptor cysteine rich
(SRCR); (ii) pentraxin (PTX); (iii) polycystine-1, lipoxygenase, alpha toxin
(LH2/PLAT); (iv) Limulus clotting factor C, Coch-5b2 and Lgl1 (LCCL). In our
assessment the PxSR molecule is completely novel in biology and is only found in
Apicomplexa parasites. We show that PxSR is expressed in sporozoites of both
human and rodent malaria species. Disruption of the PbSR gene in the rodent
malaria parasite P. berghei results in parasites that form normal numbers of
oocysts, but fail to produce any sporozoites. We suggest that, in addition to a
role in sporogonic development, PxSR may have a multiplicity of functions.