Malaria Bulletin 52: Jan 28-Feb 9, 2003
Social Sciences and Malaria Control
Lancet Infect Dis 2003 Feb;3(2):99-102
The contribution of health-care services to a sound and sustainable
Moerman F, Lengeler C, Chimumbwa J, Talisuna A, Erhart A, Coosemans M,
FM, EA, MC, and UD'A are at the Institute of Tropical Medicine, Antwerp, Belgium
HIV and AIDS, tuberculosis, and malaria, besides presenting a large mortality
and morbidity burden in developing countries, are also responsible for poor
economic development. In the past international agencies devoted resources and
efforts to control malaria and other diseases without taking into account
health-system perfomance and sustainability. Even assuming that the Global Fund
to Fight AIDS, Tuberculosis, and Malaria (GFATM)-a recent international
initiative-would provide the necessary funds, a poorly performing health-care
system will not be able to use these funds optimally. Moreover, even if all
interventions are cost-effective, their impact on mortality and morbidity will
only be marginal if access to proper care is not guaranteed. It is the
responsibility of scientists and health managers to highlight to donor agencies
the importance of an accessible and well functioning health-care system at all
levels for the control of specific diseases.
Soc Sci Med 2003 Feb;56(4):701-12
Rapid assessment procedures of malaria in low endemic countries:
community perceptions in Jepara district, Indonesia.
Utarini A, Winkvist A, Ulfa FM.
Department of Public Health, Faculty of Medicine, Gadjah Mada University, 55281,
Most studies on community perceptions toward malaria have been undertaken in
high-endemic countries, and studies from low-endemic countries have only
recently been published. Similar information is also needed for hypoendemic
countries such as Indonesia, to cope with the persistence of foci-endemic
malaria in these regions. An applied qualitative method, Rapid Assessment
Procedures, was employed during a 3-month intensive data collection period in
Jepara district, Central Java province. Data were retrieved from 38
free-listings, 28 in-depth interviews, seven focus group discussions and
unstructured observation. Qualitative thematic content analysis was applied. In
this community, malaria (known as katisen or panas tis) was considered a common
but minor illness. Insufficient understanding of malaria signs and symptoms in
the subvillages likely leads to delay in illness recognition and treatment; not
surprisingly self-treatment is common and the dosage most likely below the
recommended dose. The health center was used but when it did not work, most
people would shift back to traditional services due to cost considerations. Low
understanding and acceptance of the causal link between the mosquito and
malaria, likely leading to poor comprehension of preventive activities, as well
as confusion of malaria with dengue fever, were identified. In conclusion, this
study highlights a consistent gap between the common understanding and the
biomedical description of malaria. If case management continues to be the main
strategy in malaria control program, the emic perspective of the people must be
well-integrated into the program. Likewise, interventions to improve
home-treatment should also be developed.
J Commun Dis 2001 Dec;33(4):286-96
Knowledge amongst adult population regarding vectors of malaria
in 21 states of India.
Bhasin SK, Chaturvedi S, Sharma AK, Agarwal DP.
Deptt. of Community Medicine, UMCS & GTB Hospital, Shahadra, Delhi-110 095.
Malaria is the world's most important tropical disease which kills more people
than any other disease except tuberculosis. It is a public health problem in
more than 90 countries, inhabited by a total of some 2400 million people, 40% of
the world's population. More than 90% of all malaria cases are in sub Saharan
Africa, with two thirds of the remainder concentrated in six countries viz.
India, Brazil, Sri Lanka, Afghanistan, Vietnam and Columbia in decreasing order
of prevalence. Even now the problem of malaria in India is grossly
underestimated. A rough estimate of morbidity due to malaria made on the basis
of consumption of antimalarials comes to 35.5 million episodes in addition to
malaria cases treated by the National Anti Malaria Programme (NAMP). In addition
to large scale morbidity and mortality, it affects agricultural and industrial
produce causing great socioeconomic losses.
Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 2002;20(4):238-41
[Cost-effectiveness analysis of the current measures for malaria prevention
in Yuanjiang valley, Yunnan province] [Article in Chinese]
Xu JW, Yang H, Yang ZQ, Yang GC, Ma XW, Wang WR, Gu YA, Wang LB, Yang XW, Ma J.
- Yunnan Institute of Malaria Control, Simao 665000.
OBJECTIVE: To evaluate the cost-effectiveness analysis of the measures currently
used for malaria prevention in the region of Yuanjiang River Valley. METHODS:
The efficacy and cost-effectiveness analysis of chemoprophylaxis, single DDT
residual spraying and a combination of both were evaluated through three field
intervention trials. RESULTS: (1) From July to November, the rate ratio of
malaria incidence among building workers of expressway as the group of
chemoprophylaxis using combined piperaquine/sulfadoxine once per month was 0.35
(95% CI: 0.20-0.59); the cost per individual protected (CIP) and the cost per
case averted (CCA) were RMB 6.69 yuan and RMB 459 yuan respectively. (2) In the
hyper-endemic villages near the river, the rate ratio in the group using
chloroquine plus primaquine once every 10 days for 5 months was 0.28 (95% CI:
0.08-0.99); the CIP and CCA were RMB 5.30 yuan and RMB 300 yuan respectively.
(3) The standardized morbidity ratio (SMR) was 100%, 98% and 50% respectively
for the chemoprophylaxis group with pyrimethamine/sulfadoxine once per month
from May to September, the group with single DDT residual spraying in April and
the group of combined chemoprophylaxis and DDT spraying. The CIP was RMB 1.49,
2.48 and 3.97 yuan for the three groups respectively. As compared with the
previous year, no cases were averted from the chemoprophlaxis group; the CCA was
RMB 14,535 yuan and 908 yuan respectively for the DDT spraying group and the
group with combined measures. CONCLUSION: There was no significant difference on the chemoprophylaxis cost between the group using piperaquine/sulfadoxine
combination once per month and that of chloroquine plus primaquine once per ten
days. However, the study proved an efficacy for malaria prevention in the former
but not in the latter. In comparison with the groups of single measures, the
group with combined measures showed the best efficacy and effectiveness, but
Embo J 21(24): 6673-80. 2002.
Immune response of Anopheles gambiae to the early sporogonic stages
of the human malaria parasite Plasmodium falciparum."
Tahar, R., C. Boudin, et al. Email: [email protected]
Deciphering molecular interactions between the malaria parasite and
its mosquito vector is an emerging area of research that will be greatly
facilitated by the recent sequencing of the genomes of Anopheles gambiae
mosquito and of various Plasmodium species. So far, most such studies have
focused on Plasmodium berghei, a parasite species that infects rodents and
is more amenable to studies. Here, we analysed the expression pattern of
nine An.gambiae genes involved in immune surveillance during development of
the human malaria parasite P.falciparum in mosquitoes fed on
parasite-containing blood from patients in Cameroon. We found that
P.falciparum ingestion triggers a midgut-associated, as well as a systemic,
response in the mosquito, with three genes, NOS, defensin and GNBP, being
regulated by ingestion of gametocytes, the infectious stage of the
parasite. Surprisingly, we found a different pattern of expression of these
genes in the An.gambiae-P.berghei model. Therefore, differences in mosquito
reaction against various Plasmodium species may exist, which stresses the
need to validate the main conclusions suggested by the P.berghei-An.gambiae
model in the P.falciparum-An.gambiae system.
Proc R Soc Lond B Biol Sci 2002 Dec 22;269(1509):2551-7
Interspecific competition during transmission of two sympatric malaria
parasite species to the mosquito vector.
Paul RE, Nu VA, Krettli AU, Brey PT.
Unite de Biochimie et Biologie Moleculaire des Insectes, Institut Pasteur, 28
rue du Dr Roux, 75724 Paris cedex 15, France.
The role of species interactions in structuring parasite communities remains
controversial. Here, we show that interspecific competition between two avian
malaria parasite species, Plasmodium gallinaceum and P. juxtanucleare, occurs as
a result of interference during parasite fertilization within the bloodmeal of
the mosquito. The significant reduction in the transmission success of P.
gallinaceum to mosquitoes, due to the co-infecting P. juxtanucleare, is
predicted to have compromised its colonization of regions occupied by P.
juxtanucleare and, thus, may have contributed to the restricted global
distribution of P. gallinaceum. Such interspecies interactions may occur between
human malaria parasites and, thus, impact upon parasite species epidemiology,
especially in regions of seasonal transmission.
Br J Biomed Sci 2002;59(4):228-31
Non-microscopic method for malaria diagnosis using OptiMAL IT, a
second-generation dipstick for malaria pLDH antigen detection.
Moody AH, Chiodini PL.
Department of Clinical Parasitology, Hospital for Tropical Diseases, University
College Hospital, Mortimer Market, Capper Street, London WC1E 3BG, UK.
Email: [email protected]
Rapid diagnostic tests for malaria are now a commonly used procedure for malaria
diagnosis. New or improved devices need to be evaluated against a recognised
gold-standard procedure and subjected to conditions of temperature and humidity
that may affect their performance. The OptiMAL 48 RDT has now been available
commercially for several years and a second-generation OptiMAL IT test is now
coming onto the market. In this study the problems associated with the routine
use of OptiMAL 48 is investigated and its performance compared with a
second-generation individual test, OptiMAL IT. Sensitivity and specificity for
detection of all malaria species for both tests were comparable but loss of
sensitivity of the test strips due to humidity or temperature found with the
routine use of OptiMAL 48 was not seen with the individual OptiMAL IT.
False-positive results for Plasmodium falciparum, seen in two negative blood
samples, were attributed to the presence of high levels of heterophile
Gynecol Obstet Invest 2002;54(3):137-44
Iron status and iron deficiency anaemia in adolescents in a Tanzanian
Massawe SN, Ronquist G, Nystrom L, Lindmark G.
Department of Obstetrics and Gynaecology, Muhimbili College of Health Sciences,
Dar es Salaam, Tanzania.
OBJECTIVES: To assess the extent and degree of anaemia in adolescents in a
Tanzanian suburban area, to estimate the contribution of iron deficiency, using
serum (S)-ferritin and soluble transferrin receptor (sTfR) as markers of iron
deficiency. MATERIALS: Consecutive primigravidae at booking for antenatal care
(n = 76), primary school boys (n = 101) and postmenarchal girls (n = 130) age
>/=12 years were investigated. METHODS: Weight and height were measured; venous
blood was drawn for haematological analyses, malaria screening, S-ferritin,
sTfR, and C-reactive protein. Stool specimens were analysed for intestinal
parasites. RESULTS: Anaemia (Hb <105 g/l) was highly prevalent in adolescent
primigravidae (75.5%). Adolescent girls were more anaemic (Hb <120 g/l) than
boys (14.5 vs. 7.9%). Iron deficiency and hookworm infestation were predominant
in both groups of adolescents, however, malaria contributed more to anaemia in
the primigravidae. Nearly 40% of the anaemic primigravidae had indication of
infection, and S-ferritin was less useful as a marker of iron deficiency in this
group. sTfR identified iron deficiency in both pregnant and non-pregnant
adolescents. Copyright 2002 S. Karger AG, Basel
Gene 2003 Jan 30;304(1-2):65-75
Sequence diversity and evolution of the malaria vaccine candidate merozoite
surface protein-1 (MSP-1) of Plasmodium falciparum.
Ferreira MU, Ribeiro WL, Tonon AP, Kawamoto F, Rich SM.
Department of Parasitology, Institute for Biomedical Sciences, University of Sao
Paulo, Av. Prof. Lineu Prestes 1374, 05508-900, Sao Paulo (SP), Brazil
The merozoite surface protein-1 (MSP-1) of the malaria parasite Plasmodium
falciparum is a major blood-stage antigen containing highly polymorphic
tripeptide repeats in the domain known as block 2 and several non-repetitive
domains that are essentially dimorphic. We have analyzed sequence variation in
block 2 repeats and in non-repetitive block 17, as well as other polymorphisms
within the MSP-1 gene, in clinical isolates of P. falciparum. Repeat haplotypes
were defined as unique combinations of repeat motifs within block 2, whereas
block 17 haplotypes were defined as unique combinations of single nucleotide
replacements in this domain. A new block 17 haplotype, E-TNG-L, was found in one
isolate from Vietnam. MSP-1 alleles, defined as unique combinations of
haplotypes in blocks 2 and 17 and other polymorphisms within the molecule, were
characterized in 60 isolates from hypoendemic Brazil and 37 isolates from
mesoendemic Vietnam. Extensive diversity has been created in block 2 and
elsewhere in the molecule, while maintaining significant linkage disequilibrium
between polymorphisms across the non-telomeric MSP-1 locus separated by a map
distance of more than 4 kb, suggesting that low meiotic recombination rates
occur in both parasite populations. These results indicate a role for
non-homologous recombination, such as strand-slippage mispairing during mitosis
and gene conversion, in creating variation in a malarial antigen under strong
Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 2002;20(3):145-7
[Application of multifactor spatial composite model to predict transmission
tendency of malaria at national level] [Article in Chinese]
Yang GJ, Zhou XN, Malone JB, McCarroll JC, Wang TP, Liu JX.
Jiangsu Institute of Parasitic Diseases, Wuxi 214064.
OBJECTIVE: To predict the transmission tendency of malaria at national level by
application of geographic information system(GIS) technique. METHODS: With the
assistance of ArcView 3.0 a software and its spatial analyst extension, the
surface spatial analysis on three natural factors, namely, total growing degree
days(TGDD), precipitation and relative humidity, were conducted individually.
The map calculation was preformed based on the three factors' ratio of 5:3:2
resulted from the Delphi investigation. RESULTS: The individual maps and
composition map of TGDD, precipitation and relative humidity were created,
respectively, based on the spatial composite model, which were used to predict
the transmission tendency of malaria at national level. CONCLUSION: The high
risk areas for malaria transmission, predicted by the spatial composite model
based on the multilayers of environmental factors, are correlated with the
previous reports. This will, therefore, provide information for predicting
malaria transmission by multiple factors in a larger area.
Hum Mol Genet 2003 Feb 15;12(4):375-8
Linkage of mild malaria to the major histocompatibility complex in families
living in Burkina Faso.
Flori L, Sawadogo S, Esnault C, Delahaye NF, Fumoux F, Rihet P.
Universite de la Mediterranee, Marseille, France.
Tumor necrosis factor alpha (TNFalpha) is thought to be a critical mediator of
malaria fever, and mild malaria was previously reported to be linked to the MHC
region containing the tumor necrosis factor alpha gene (TNF). Thirty-four
families from Burkina Faso were analyzed to test for linkage between
polymorphisms within the MHC region and mild malaria using the
maximum-likelihood-binomial (MLB) program. Two-point analysis indicated linkage
of mild malaria to TNFd (LOD=3.27; P= 5.44x10(-5)). Using multipoint analysis,
we also found evidence for linkage of mild malaria to the MHC region, with a
peak close to TNF (LOD=3.86; P=1.22x10(-5)). Our results support genes within
the MHC region being involved in mild malaria. In particular, the genetic
variation within TNF may influence susceptibility to mild malaria. Nevertheless,
TNF-238, TNF-244 and TNF-308 polymorphisms are unlikely to explain linkage of
mild malaria to the MHC region, and the causal mutations remain to be
Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 1999;17(1):1-4
[A pilot study on malaria control by using a new strategy of combining
strengthening infection source treatment and health education in mountainous
areas of Hainan province] [Article in Chinese]
Chen W, Wu K, Lin M, Tang L, Gu Z, Wang S, Lan C, Lan X, Li H, Huang M, Chen X,
Hainan Provincial Institute of Tropical Diseases, Haikou 570203.
AIM: To explore a new malaria control strategy that fits current
epiodemiological condition and coincides with modern medicine model and the
principle of cost-benefit. METHODS: The new strategy highlights the risk
villages and risk population as the focal point and integrates health education
with behavioral intervention. The main anti-malaria measures consists of
carrying out health education in risk villages, giving mass drug administrations
in risk population staying overnight in the mountain, following up malaria cases
for implementing radical cure, but without using traditional residual spraying
or impregnating bednets with insecticides. RESULTS: After having adopted the new
strategy and taken the control measures, the people's knowledge about malaria
increased to a higher level and the indices of malaria reduced to a lower level.
The rate of bednet-using in the population was increased from 26.8% to 72.6%.
The annual parasite incidence (API) of malaria was declined from 3.5% in 1994 to
1.1% in 1996 and 0.8% in 1997, and the API of falciparum malaria was declined
from 1.0% to 0.3% and 0.3% respectively in the townships at the same time. The
parasite rate(PR) of malaria was declined from 7.2% in May, 1995 to 2.1% in
November, 1996 and 1.2% in October, 1997 and the PR of falciparum malaria was
declined from 1.2% in May, 1995 to 0.1% in October, 1997. The proportion of
villages without malaria cases was increased from 18.6% in 1994 to 54.2% in
1997, and the number of risk villages with a malaria incidence above 5% was
reduced from 14 to 2 at the same time. The ratio of cost/benefit was 1:2.4 in
1995-1996 and 1:4.4 in 1997, showing a better economic benefit.
CONCLUSION: The expectant result has been obtained, thereby providing new
experience for the malaria control in the mountainous areas of Hainan Province.
Mem Inst Oswaldo Cruz 2002 Dec;97(8):1221-3
Effects of chloroquine and sulfadoxine/pyrimethamine on gametocytes
in patients with uncomplicated Plasmodium falciparum malaria in Colombia.
Osorio L, Ferro BE, Castillo CM.
London School of Hygiene and Tropical Medicine, London, UK.
The effect of antimalarials on gametocytes can influence transmission and the
spread of drug resistance. In order to further understand this relationship, we
determined the proportion of gametocyte carriers over time post-treatment in
patients with uncomplicated Plasmodium falciparum malaria who were treated with
either chloroquine (CQ) or sulfadoxine/pyrimethamine (SP). The overall
proportion of gametocyte carriers was high (85%) and not statistically
significantly different between the CQ and SP treatment groups. However, an
increased risk of carrying gametocytes on day 14 of follow up (1.26 95% CI
1.10-1.45) was found among patients having therapeutic failure to CQ compared
with patients having an adequate therapeutic response. This finding confirms and
extends reports of increased risk of gametocytaemia among CQ resistant P.
Mem Inst Oswaldo Cruz 2002 Dec;97(8):1191-5
Morphometric discrimination of females of five species of Anopheles of the
subgenus Nyssorhynchus from Southern and Northwest Colombia.
Calle L DA, Qui ones ML, Erazo HF, Jaramillo O N.
Programa de Estudio y Control de Enfermedades Tropicales, Instituto de Biolog a,
Universidad de Antioquia, Medell n, Colombia.
The most important vectors of human Plasmodium in the neotropics belong to the
subgenus Nyssorhynchus. These species are generally sympatric in terms of their
geographical distributions. Some are difficult to identify based solely on
examination of adult females using the available morphological keys, in these
cases examination of immature stages and male genitalia is required to make
correct determinations. However, in epidemiological studies it is necessary to
identify the species of adult females which are found near humans, i.e. in
studies of malaria transmission or evaluation of control measures. The purpose
of the present study was to evaluate the discrimination of adult females of
different species of Nyssorhynchus isolated mainly from Southern Colombia
(department of Putumayo), using morphometric analysis. Adult females were
obtained after rearing larvae collected in natural breeding places and from the
progeny of females collected on humans. The morphological characteristics of the
immature stages allowed the identification of four species of the subgroup
Oswaldoi from Southern Colombia: Anopheles rangeli Gabaldon, Cova Garcia &
Lopez, An. oswaldoi (Peryassu), An. benarrochi Gabaldon, Cova Garcia & Lopez and
An. triannulatus (Neiva & Pinto). The species An. nuneztovari (Gabaldon) from
the Northwest of Colombia was included for comparison. Morphometric analysis
allowed differentiation of the females of all species to a confidence level
approaching 90% using principal components analysis of 10 wing and leg
variables, followed by canonical variate analysis of the first four principal
components. We conclude that morphometrics may represent a useful taxonomic
tool for this group and that its use should be further studied.
Z Naturforsch [C] 2002 Nov-Dec;57(11-12):1022-7
Herbal remedies traditionally used against malaria in Ghana:
bioassay-guided fractionation of Microglossa pyrifolia (Asteraceae).
Kohler I, Jenett-Siems K, Kraft C, Siems K, Abbiw D, Bienzle U, Eich E.
Institut fur Pharmazie (Pharmazeutische Biologie), Freie Universitat Berlin,
Konigin-Luise-Strasse 2+4, D-14195 Berlin, Germany.
Different extracts from 11 West African plants traditionally used against
malaria in Ghana were tested against both the chloroquine-sensitive strain PoW
and the chloroquine-resistant clone Dd2 of Plasmodium falciparum. Due to the
promising in vitro activity of the lipophilic extract [IC50: 10.5 microg/ml
(PoW); 13.1 microg/ml (Dd2)], Microglossa pyrifolia (Lam.) Kuntze (Asteraceae)
was chosen for further phytochemical investigation. From active fractions 13
compounds were isolated; their structures were established on the basis of
spectroscopic methods. 1-Acetyl-6E-geranylgeraniol-19-oic acid and sinapyl
diangelate represent new natural compounds. The two diterpenes E-phytol [IC50:
8.5 microM (PoW); 11.5 microM (Dd2)], and 6E-geranylgeraniol-19-oic acid [IC50:
12.9 microM (PoW); 15.6 microM (Dd2)] proved to be the most active constituents
in our test system.
J Egypt Soc Parasitol 1999;29(1):215-22
Plasma levels of nitric oxide in association with severe Plasmodium falciparum
Agina AA, Abd-Allah SH.
Department of Tropical Medicine, Al Azhar Faculty of Medicine, Cairo, Egypt.
One hundred and five patients with Plasmodium falciparum were included,
forty-three with cerebral malaria and sixty-two without cerebral manifestations.
The main clinical presentations in cerebral malaria patients were fever (76.4%),
pallor (72%), splenomegaly (60.5%), deep coma (39.5%), jaundice (18.6%),
pulmonary oedema (13.9%), subconjunctival haemorrhage (13.9%), severe anemia
(Hb<5mg/l) (53.5%), hypoglycemia (glucose<40mg/dl) (67.4%) and haemoglobinuria
(6.9%) while in non cerebral malaria patients the clinical presentations were fever
(83.8%), pallor (67.7%), splenomegaly (66%), jaundice (9.7%), severe anemia
(Hb<5gm/dl) (51.6%) and hypoglycemia (glucose<40mg/dl) (3.2%). Nine patients
from cerebral malaria group died after admission. Serum level of nitric oxide
(nitrite plus nitrate) were assayed for all patients, serum level of nitric oxide were
highly significant in patients with cerebral malaria than those without
(34.6 +/- 2.3n. mol/ml VS 12.9 +/- 1.3n. mol/ml; P<0.01). In
cerebral malaria, nitric oxide levels were highly elevated in patients with
deeper coma than those with lighter coma (48.2 +/- 3.1n. mol/ml VS 24.4 +/-
1.3n. mol/ml; P<0.001) and also higher among patients with longer duration of
coma (>72 hours) than among patients with shorter duration of coma (<72 hours)
(54.5 +/- 2.8 n. mol/ml V.S. 23.6 +/- 3.1n. mol/ml; P<0.001). Also, nitric oxide
levels were correlated with clinical outcome, fatal cases (9 patients) having
significantly higher nitric oxide levels than survivors (56.2 +/- 3.1 n. mol/ml
VS 32.5 +/- 1.3 n. mol/ml; P<0.001). Thus, higher levels of nitric oxide are
associated with indices of disease severity and may predict outcome in-patients
with cerebral malaria. These data are consistent with the hypothesis that nitric
oxide is involved in the pathogenesis of cerebral malaria.
Science 2003 Jan 31;299(5607):705-8
Dissecting apicoplast targeting in the malaria parasite Plasmodium falciparum.
Foth BJ, Ralph SA, Tonkin CJ, Struck NS, Fraunholz M, Roos DS, Cowman AF,
Plant Cell Biology Research Centre, School of Botany, University of Melbourne,
Parkville, VIC 3010, Australia.
Transit peptides mediate protein targeting into plastids and are only poorly
understood. We extracted amino acid features from transit peptides that target
proteins to the relict plastid (apicoplast) of malaria parasites. Based on these
amino acid characteristics, we identified 466 putative apicoplast proteins in
the Plasmodium falciparum genome. Altering the specific charge characteristics
in a model transit peptide by site-directed mutagenesis severely disrupted
organellar targeting in vivo. Similarly, putative Hsp70 (DnaK) binding sites
present in the transit peptide proved to be important for correct targeting.
Blood 2003 Jan 30; [epub ahead of print]
CCR5 deficiency decreases susceptibility to experimental cerebral malaria.
Belnoue E, Kayibanda M, Deschemin JC, Viguier M, Mack M, Kuziel WA, Renia L.
Departement d'Immunologie, Institut Cochin, Paris, France.
Infection of susceptible mouse strains with Plasmodium berghei ANKA (PbA) is a
valuable experimental model of cerebral malaria (CM). Two major pathological
features of CM are the intravascular sequestration of infected erythrocytes and
leukocytes inside brain microvessels. We have recently shown that only the
CD8(+) T cell subset of these brain-sequestered leukocytes is critical for
progression to CM. The chemokine receptor CCR5 is an important regulator of
leukocyte trafficking in the brain in response to fungal and viral infection.
Therefore, we investigated whether CCR5 plays a role in the pathogenesis of
experimental CM. Approximately 70-85% of wild-type and CCR5(+/-) mice infected
with PbA developed CM, whereas only about 20% of PbA-infected CCR5-deficient
mice exhibited the characteristic neurological signs of CM. The brains of
wild-type mice with CM showed significant increases in CCR5(+) leukocytes,
particularly CCR5(+) CD8(+) T cells, as well as increases in Th1 cytokine
production. The few PbA-infected CCR5-deficient mice that developed CM exhibited
a similar increase in CD8(+) T cells. Significant leukocyte accumulation in the
brain and Th1 cytokine production did not occur in PbA-infected CCR5-deficient
mice that did not develop CM. Moreover, experiments using bone marrow (BM)
chimeric mice showed that a reduced but significant proportion of deficient mice
grafted with CCR5(+) BM develop CM, indicating that CCR5 expression on a
radiation-resistant brain cell population is necessary for CM to occur. Taken
together, these results suggest that CCR5 is an important factor in the
development of experimental CM.
Vaccine 2003 Mar 7;21(11-12):1033-1043
Expression, polymorphism analysis, reticulocyte binding and serological
reactivity of two Plasmodium vivax MSP-1 protein recombinant fragments.
Espinosa AM, Sierra AY, Barrero CA, Cepeda LA, Cantor EM, Lombo TB, Guzman F,
Avila SJ, Patarroyo MA.
Fundacion Instituto de Inmunologi;a de Colombia, Bogota, Colombia
Among the four parasite species causing malaria in humans, Plasmodium vivax
prevails on both the Asian and the American continents. Several antigens from
this parasite's erythrocytic stages have been characterised and some of them are
considered to be good vaccine candidates. The P. vivax merozoite surface
protein-1 (PvMSP-1) is a 200kDa antigen, thought to mediate the initial contact
between the merozoite and the erythrocyte. An effective blockage of this
interaction could be important in anti-malarial vaccine design. This study
analyses the genetic polymorphism, binding to both reticulocytes and
erythrocytes, antigenicity and immunogenicity of two recombinant proteins
belonging to the 33kDa PvMSP-1 proteolytic fragment. Both regions showed very
low genetic variation, bound reticulocytes with higher affinity than
erythrocytes, were recognised by naturally P. vivax-infected patient sera and
were immunogenic when used to immunise rabbits, making them good vaccine
candidates against P. vivax, to be further preclinically tested in the Aotus
J Egypt Soc Parasitol 2001 Apr;31(1):177-86
Studies on the present status of insecticides resistance on mosquitoes
using the diagnostic dosages in El-Fayium Governorate, a spot area of
malaria in Egypt.
Mostafa AA, Allam KA.
Research Institute of Medical Entomology, Ministry of Health and Population,
Dokki, Giza, Egypt.
Insecticides susceptibility tests were conducted using the World Health
Organization diagnostic doses on the adult and larvae of Anopheles pharoensis
and Culex pipiens mosquitoes from Fayium Governorate in Egypt. Insecticides used
were malathion, fenitrothion, temephos, diazinon, bromophos and fenthion from
organophosphorous group and deltamethrin, permethrin and cypermethrin from
synthetic pyrethroid group while propoxur was from carbamate group. Larvae of A.
pharoensis were resistant to fenitrothion and susceptible to other insecticides
used, while the adults were susceptible to malathion, deltamethrin, fenitrothion
and premethrin. Larvae of C. pipiens were resistant to temephos, fenitrothion,
bromophos and fenthion and susceptible to malathion, permethrin and diazinon,
while the adults were resistant to fenitrothion, permethrin and propoxur and
susceptible to deltamethrin, cypermethrin and malathion. These results are
important for the success of the control programmes and monitoring the
susceptibility status of vectors.
Am J Trop Med Hyg 2003 Jan;68(1):120-3
Efficacy of chloroquine, sulfadoxine-pyrimethamine, and mefloquine
for the treatment of uncomplicated Plasmodium falciparum malaria
on the north coast of Peru.
Marquino W, MacArthur JR, Barat LM, Oblitas FE, Arrunategui M, Garavito G,
Chafloque ML, Pardave B, Gutierrez S, Arrospide N, Carrillo C, Cabezas C,
Ruebush TK 2nd.
Instituto Nacional de Salud, Lima, Peru
As part of an effort to assess antimalarial drug resistance in Peru, we carried
out 14-day in vivo efficacy trials of chloroquine (CQ; 25 mg/kg) and
sulfadoxine-pyrimethamine (SP; 25 mg/kg of the sulfadoxine component) for the
treatment of uncomplicated Plasmodium falciparum infections at three sites on
the northern coast of Peru. Mefloquine (MQ; 15 mg/kg) also was evaluated at one
site. The results from all three sites were similar. Of the 53 patients treated
with CQ, 58.5% had RII/RIII responses. No RIII failures were observed among the
112 patients who received SP, but 4.5% and 1.8%, respectively, had RII and RI
responses. All 33 patients treated with MQ showed a sensitive response. Early
treatment failures were observed in 27.1% of the CQ patients but in no patients
receiving SP or MQ. Late treatment failures were seen in 59.3% of the CQ
patients and 6.4% of the SP patients but in none of those treated with MQ. Based
on these findings and because of concern about the potential for development of
resistance if SP were used alone, the National Malaria Control Program is
planning a change in malaria treatment policy to SP-artesunate combination
therapy for this region of the country.
Am J Trop Med Hyg 2003 Jan;68(1):107-10
Lack of prediction of mefloquine and mefloquine-artesunate treatment
outcome by mutations in the Plasmodium falciparum multidrug resistance
1 (pfmdr1) gene for P. falciparum malaria in Peru.
Pillai DR, Hijar G, Montoya Y, Marouino W, Ruebush TK 2nd, Wongsrichanalai C,
Tropical Disease Unit, Toronto General Hospital and University of Toronto,
Toronto, Ontario, Canada.
We assessed whether mutations in the Plasmodium falciparum multidrug-resistance
gene 1 (pfmdr1) (C1034S, D1042N, and Y1246D) would predict treatment outcome
during a 28-day in vivo treatment trial in the Peruvian Amazon. Mefloquine (MQ)
was compared with mefloquine-artesunate (MQ-AS) in a randomized, multi-clinic
protocol for the first time in the Americas. Of 115 patients enrolled in the in
vivo arm, 97 patients were eligible for molecular analysis. All 97 patients
remained parasite-free during 28 days of follow-up (MQ, n = 46; MQ-AS, n = 51),
indicating 100% clinical efficacy of the MQ and MQ-AS treatment regimens. The
reported MQ-sensitive alleles (C1034, D1042, and Y1246) were present in 48.5% (n
= 47) of the cases, whereas 49 isolates (50.5%) contained the D1246 mutation
reported to confer MQ resistance in vitro. However, neither this mutation nor a
double mutation (S1034, D1246; n = 16) was predictive of MQ treatment outcome.
Proteins 2003 Feb 15;50(3):464-73
Comparative properties of a three-dimensional model of Plasmodium
falciparum ornithine decarboxylase.
Birkholtz L, Joubert F, Neitz AW, Louw AI.
Department of Biochemistry, School of Biological Sciences, Faculty of Natural
and Agricultural Sciences, University of Pretoria, Pretoria, South Africa.
The ornithine decarboxylase (ODC) component of the bifunctional
S-adenosylmethionine decarboxylase/ornithine decarboxylase enzyme
(PfAdoMetDC-ODC) of Plasmodium falciparum was modeled on the crystal structure
of the Trypanosoma brucei enzyme. The homology model predicts a doughnut-shaped
active homodimer that associates in a head-to-tail manner. The monomers contain
two distinct domains, an N-terminal alpha/beta-barrel and a C-terminal modified
Greek-key domain. These domains are structurally conserved between eukaryotic ODC
enzymes and are preserved in distant analogs such as alanine racemase and
triosephosphate isomerase-like proteins. Superimposition of the PfODC model on
the crystal structure of the human enzyme indicates a significant degree of deviation
in the carbon alpha-backbone of the solvent accessible loops. The surface locality of
the ab initio modeled 38 amino acid parasite-specific insert
suggests a role in the stabilization of the large bifunctional protein complex.
The active site pockets of PfODC at the interface between the monomers appear to
be conserved regarding the binding sites of the cofactor and substrate, but each
contains five additional malaria-specific residues. The predicted PfODC homology
model is consistent with mutagenesis results and biochemical studies concerning
the active site residues and areas involved in stabilizing the dimeric form of
the protein. Two competitive inhibitors of PfODC could be shown to interact with
several parasite-specific residues in comparison with their interaction with the
human ODC. The PfODC homology model contributes toward a structure-based
approach for the design of novel malaria-specific inhibitors. Proteins
2003;50:464-473. Copyright 2003 Wiley-Liss, Inc.
Proteins 2003 Feb 15;50(3):400-9
Alpha helix shortening in 1522 MSP-1 conserved peptide analogs is
associated with immunogenicity and protection against P. falciparum malaria.
Cubillos M, Espejo F, Purmova J, Martinez JC, Patarroyo ME.
Fundacion Instituto de Inmunologia de Colombia (FIDIC), Bogota, Colombia.
1522 is a nonimmunogenic conserved high-activity binding peptide (HABP)
belonging to Plasmodium falciparum MSP-1 protein N-terminal fragment. The key
amino acids in binding to red blood cells (RBC) were identified and replaced by
others having similar mass but different charge. Because conserved HABPs are not
antigenic nor immunogenic, immunogenicity and protectivity studies were then
conducted on them in the Aotus monkey. (1)H-NMR studies included the lead
peptide 1522 as well as the analogs 9782, 13446, 13448, and 13442 to relate
their structure to biological function. All the peptides presented alpha-helical
structure, with differences observed in helix location and extension. The
nonprotective 1522 peptide was totally helical from the N- to the C-terminus,
very similar to nonprotective 13442 and 13448 peptides whose extension was
almost totally helical. The 9782 and 13446 protective peptides, however,
possessed a shorter helical region where modified critical binding residues were
not included. A more flexible region was generated at the C-terminus in those
peptides with a shorter helical region, leading to a greater number of
conformers. These data suggest that peptide flexibility results in increased
interaction with immune system molecules, generating protective immunity.
Proteins 2003;50:400-409. Copyright 2003 Wiley-Liss, Inc.
Am J Trop Med Hyg 2003 Jan;68(1):115-9
Placental monocyte infiltrates in response to Plasmodium falciparum
malaria infection and their association with adverse pregnancy outcomes.
Rogerson SJ, Pollina E, Getachew A, Tadesse E, Lema VM, Molyneux ME.
Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of
Medicine, University of Malawi, Blantyre, Malawi.
Email: [email protected]
Maternal anemia and low birth weight (LBW) may complicate malaria in pregnancy,
and placental monocyte infiltrates have been associated with LBW, and
anecdotally with anemia. We examined placental pathology from 357 Malawian
women. Intervillous monocyte infiltrates were frequent in placental malaria and
were not seen in uninfected placentas. Histology was grouped according to a
5-point scale. Dense monocyte infiltrates and presence of intramonocytic malaria
pigment were associated with anemia and LBW. Of factors associated with LBW
and/or anemia in univariate analysis, gravidity (P = 0.002), number of antenatal
clinic (ANC) visits (P < 0.001), malaria pigment in fibrin (P = 0.03), and
monocyte malaria pigment (P = 0.0001) remained associated with lower birth
weight by multivariate analysis. Associated with maternal anemia were HIV
infection (P < 0.0001), intervillous monocyte numbers (P < 0.0001), number of
ANC visits (P = 0.002), and recent febrile symptoms (P = 0.0001).
Pigment-containing placental monocytes are associated with anemia and LBW due to
malaria, and may have a causative role in their development.
Am J Trop Med Hyg 2003 Jan;68(1):111-4
Persistence of atovaquone in human sera following treatment: inhibition of
Plasmodium falciparum development in vivo and in vitro.
Butcher GA, Sinden RE.
Department of Biologic Sciences, Imperial College of Science Technology and
Medicine, London, UK.
Email: [email protected]
Published pharmacokinetic data indicate that after treatment of patients with
therapeutic doses of atovaquone/proguanil hydrochloride (Malarone,
GlaxoSmithKline Research Triangle Park, NC), the plasma half-lives of these
drugs are 70h and 15h, respectively. However, using two biologic assays
(mosquito transmission and in vitro asexual stage development), we demonstrate
here that sera from volunteers treated with atovaquone/proguanil retained
activity against Plasmodium falciparum up to 6 weeks after such treatment. This
activity was due to atovaquone, as administration of this drug alone replicated
the data obtained with the combination. Most notably, asexual stage development
of an atovaquone-resistant strain (NGATV01) of P. falciparum was not inhibited
by sera taken after atovaquone treatment. These data indicate that for
atovaquone, biologic assays, though not quantitative, are more sensitive than
the usual physicochemical assays. Also, persistence of atovaquone in plasma at
low concentrations for long periods may increase the risk of resistant parasites
Am J Trop Med Hyg 2003 Jan;68(1):102-6
Serum cytokine profiles in patients with Plasmodium vivax malaria: a
comparison between those who presented with and without hyperpyrexia.
Seoh JY, Khan M, Park SH, Park HK, Shin MH, Ha EH, Lee BE, Yoo K, Han HS, Oh S,
Wi JH, Hong CK, Oh CH, Kim YA, Park JW.
Department of Microbiology, Parasitology, Preventive Medicine, Internal
Medicine, and Surgery, College of Medicine, Ewha Womans University, Seoul,
Serum cytokine profiles in patients with Plasmodium vivax malaria who presented
with and without hyperpyrexia were compared by a retrospective review of the
medical records of the consecutive patients seen at the military hospitals near
the demilitarized zone in the Republic of Korea from April 2000 through October
2001. Of 162 male patients studied, 120 (86.4%) presented with hyperpyrexia
(i.e., an axillary temperature > or = 40 degrees C). The mean +/- SEM ages of
the patients with and without hyperpyrexia were 21.5 +/- 0.14 and 21.9 +/- 0.39
years, respectively (P = 0.33). The mean +/- SEM concentrations of serum
interleukin (IL)-6 (379.7 +/- 44.1 pg/mL versus 105.4 +/- 26.8 pg/mL; P =
0.002), IL-10 (583.4 +/- 58.2 pg/mL versus 142.4 +/- 39.7 pg/mL; P = 0.0001),
and interferon-gamma (312.6 +/- 33.9 pg/mL versus 112.9 +/- 27.1 pg/mL; P =
0.0001) were significantly higher in patients with hyperpyrexia compared with
those without hyperpyrexia. The mean +/- SEM concentrations of serum tumor
necrosis factor-alpha were 155.5 +/- 54.5 pg/mL and 109.9 +/- 29.3 pg/mL (P =
0.27) in patients who presented with and without hyperpyrexia, respectively.
Further studies are needed to examine whether serum concentrations of these
cytokines also parallel their concentrations at the tissue sites of their
production and action.
Am J Trop Med Hyg 2003 Jan;68(1):97-101
Protective efficacy of the RTS,S/AS02 Plasmodium falciparum malaria
vaccine is not strain specific.
Alloueche A, Milligan P, Conway DJ, Pinder M, Bojang K, Doherty T, Tornieporth
N, Cohen J, Greenwood BM.
Department of Infectious and Tropical Diseases, London School of Hygiene and
Tropical Medicine, London, United Kingdom. [email protected]
RTS,S/AS02 is a recombinant protein malaria vaccine that contains a large
portion of the C-terminal of the circumsporozoite protein (CSP) sequence of the
NF54 isolate of Plasmodium falciparum fused to the hepatitis B virus surface
antigen. It has been shown to induce significant protection to challenge
infection with a homologous parasite strain in American volunteers. In a
recently completed trial in semi-immune Gambian adults, vaccine efficacy against
natural infection was 34% (95% confidence interval = 8-53%, P = 0.014) during
the malaria season following vaccination. Breakthrough P. falciparum parasites
sampled from vaccinated subjects and from controls were genotyped at two
polymorphic regions of the csp gene encoding T cell epitopes (csp-th2r and
csp-th3r) to determine if the vaccine conferred a strain-specific effect. The
overall distribution of csp allelic variants was similar in infections occurring
in vaccine and control groups. Also, the mean number of genotypes per infection
in the RTS,S/AS02 group was not reduced compared with the controls.
J Infect Dis 2003 Feb 1;187(3):522-5
Loss of red blood cell-complement regulatory proteins and increased levels
of circulating immune complexes are associated with severe malarial anemia.
Stoute JA, Odindo AO, Owuor BO, Mibei EK, Opollo MO, Waitumbi JN.
US Army Medical Research Unit, and Kenya Medical Research Institute, Nairobi,
Kenya, and Department of Medicine, Uniformed Services University of Health
Sciences, Bethesda, Maryland, USA.
Email: [email protected]
Severe anemia is one of the most lethal complications of Plasmodium falciparum
malaria. Red blood cells (RBCs) from children with severe malarial anemia are
deficient in complement regulatory proteins (CR1 and CD55). A case-control, age-
and sex-matched study was carried out to determine whether these deficiencies
are acquired or inherited and the relative contribution of these complement
regulatory protein deficiencies, the immune complex level, and the parasite
density to the development of severe malarial anemia. RBC CR1 and CD55
deficiencies resolved after treatment, suggesting that these changes were
acquired. Using conditional logistic regression, a decline in CD55 (or CR1)
(odds ratio [OR], 4.2; 95% confidence interval [CI], 2.1-8.1; P<.001) and an
increase in immune complex level (OR, 2.6; 95% CI, 1.5-4.8; P=.001) were
significantly associated with severe malarial anemia.
J Infect Dis 2003 Feb 1;187(3):477-83
Common Surface-Antigen var Genes of Limited Diversity Expressed by
Plasmodium falciparum Placental Isolates Separated by Time and Space.
Khattab A, Kremsner PG, Klinkert MQ.
Institute for Tropical Medicine, University of Tubingen, Tubingen, Germany.
Plasmodium falciparum placental parasites from Cameroon have been shown to
express surface variant var genes encoding Duffy binding-like (DBL)-gamma
domains that bind chondroitin sulfate A. All 5 domains exhibited sequences with
39%-55% amino acid (aa) identities and appear sufficiently conserved to function
in receptor binding. Transcripts of 2 samples showed complete conservation over
4 kb, demonstrating for the first time distinct conserved placental var genes.
Four placental isolates from Gabon collected 4 years later expressed DBL-gamma
sequences with 85%-99% aa identities to those from Cameroon, confirming the
conserved nature of placental variants separated by time and location. Five
peripheral parasites from children also displayed DBL-gamma sequences with
75%-97% homologies. From this, it can be concluded that P. falciparum parasites
expressing unique var DBL-gamma genes can cause placental malaria, referred to
as varPAM genes. This demonstration of structurally/functionally constrained
DBL-gamma chondroitin sulfate A-binding domains is relevant to understanding
pregnancy-associated malaria pathogenesis and to vaccine development.
J Infect Dis 2003 Feb 1;187(3):467-476
Treatment History and Treatment Dose Are Important Determinants of
Sulfadoxine-Pyrimethamine Efficacy in Children with Uncomplicated
Malaria in Western Kenya.
Terlouw DJ, Courval JM, Kolczak MS, Rosenberg OS, Oloo AJ, Kager PA, Lal AA,
Nahlen BL, Ter Kuile FO.
Division of Parasitic Diseases, National Center for Infectious Diseases, Centers
for Disease Control and Prevention, Atlanta, Georgia, USA; Kenya Medical
Research Institute, Center for Vector Biology and Control Research, Kisumu,
Kenya; and Department of Infectious Diseases, Tropical Medicine, and AIDS,
Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
This study retrospectively studied amendable determinants of
sulfadoxine-pyrimethamine (SP) efficacy involving 2869 treatments among 1072
Kenyan children <5 years old who had uncomplicated malaria. The dose was based
on age: one-quarter tablet was given to infants <1 year old, one-half tablet was
given to 1-3-year-old children, and a full tablet was given to 4-year-old
children. Only 23.5% received the internationally recommended target dose of
25/1.25 mg of SP per kg of body weight. SP intake in the previous 15-35 days
(adjusted relative risk, 1.67; 95% confidence interval, 1.35-2.07) and low SP
dose (<27.5/1.375 mg/kg) (adjusted relative risk, 1.58; 95% confidence interval,
1.17-2.13) explained 38% of parasitological treatment failures by day 7.
Patients with recent SP intake are likely to have recrudescent infections and
may need close follow-up if treated with SP or alternative treatment. Applying
our weight-for-age data to 31 existing age-based SP dose recommendations
predicted that 22 of them would result in underdosing of >25% of children <5
years. Many age-based dose recommendations need urgent revision, because SP is
increasingly used as first-line treatment in sub-Saharan Africa.
J Infect Dis 2003 Feb 1;187(3):461-6
Platelet accumulation in brain microvessels in fatal pediatric cerebral malaria.
Grau GE, Mackenzie CD, Carr RA, Redard M, Pizzolato G, Allasia C, Cataldo C,
Taylor TE, Molyneux ME.
Experimental Parasitology Unit, IFR48, Universite de la Mediterranee, Marseille,
Email: [email protected]
The pathogenesis of fatal cerebral malaria (CM) is not well understood, in part
because data from patients in whom a clinical diagnosis was established prior to
death are rare. In a murine CM model, platelets accumulate in brain
microvasculature, and antiplatelet therapy can improve outcome. We determined
whether platelets are also found in cerebral vessels in human CM, and we
performed immunohistopathology for platelet-specific glycoprotein, GPIIb-IIIa,
on tissue from multiple brain sites in Malawian children whose fatal illness was
severe malarial anemia, CM, or nonmalarial encephalopathy. Platelets were
observed in 3 locations within microvessels: between malaria pigment and
leukocytes, associated with malaria pigment, or alone. The mean surface area of
platelet staining and the proportion of vessels showing platelet accumulation
were significantly higher in patients with CM than in those without it. Platelet
accumulation occurs in the microvasculature of patients with CM and may play a
role in the pathogenesis of the disease.
Biochemistry 2003 Feb 4;42(4):1160-1169
The Initiating Steps of a Type II Fatty Acid Synthase in Plasmodium
falciparum are Catalyzed by pfacp, pfmcat, and pfKASIII.
Prigge ST, He X, Gerena L, Waters NC, Reynolds KA.
Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins
Bloomberg School of Public Health, Baltimore, Maryland 21205, Division of
Experimental Therapeutics, Walter Reed Army Institute of Research, Silver
Spring, Maryland 20910-5100, and Department of Medicinal Chemistry and Institute
for Structural Biology and Drug Discovery, Virginia Commonwealth University,
Richmond, Virginia 23219.
Malaria, a disease caused by protozoan parasites of the genus Plasmodium, is one
of the most dangerous infectious diseases, claiming millions of lives and
infecting hundreds of millions of people annually. The pressing need for new
antimalarials has been answered by the discovery of new drug targets from the
malaria genome project. One of the early findings was the discovery of two genes
encoding Type II fatty acid biosynthesis proteins: ACP (acyl carrier protein)
and KASIII (beta-ketoacyl-ACP synthase III). The initiating steps of a Type II
system require a third protein: malonyl-coenzyme A:ACP transacylase (MCAT). Here
we report the identification of a single gene from P. falciparum encoding pfMCAT
and the functional characterization of this enzyme. Pure recombinant pfMCAT
catalyzes malonyl transfer from malonyl-coenzyme A (malonyl-CoA) to pfACP. In
contrast, pfACP(trans), a construct of pfACP containing an amino-terminal
apicoplast transit peptide, was not a substrate for pfMCAT. The product of the
pfMCAT reaction, malonyl-pfACP, is a substrate for pfKASIII, which catalyzes the
decarboxylative condensation of malonyl-pfACP and various acyl-CoAs. Consistent
with a role in de novo fatty acid biosynthesis, pfKASIII exhibited typical KAS
(beta-ketoacyl ACP synthase) activity using acetyl-CoA as substrate (k(cat) 230
min(-)(1), K(M) 17.9 +/- 3.4 &mgr;M). The pfKASIII can also catalyze the
condensation of malonyl-pfACP and butyryl-CoA (k(cat) 200 min(-)(1), K(M) 35.7
+/- 4.4 &mgr;M) with similar efficiency, whereas isobutyryl-CoA is a poor
substrate and displayed 13-fold less activity than that observed for acetyl-CoA.
The pfKASIII has little preference for malonyl-pfACP (k(cat)/K(M) 64.9
min(-)(1)&mgr;M(-)(1)) over E. coli malonyl-ACP (k(cat)/K(M) 44.8
min(-)(1)&mgr;M(-)(1)). The pfKASIII also catalyzes the acyl-CoA:ACP
transacylase (ACAT) reaction typically exhibited by KASIII enzymes, but does so
almost 700-fold slower than the KAS reaction. Thiolactomycin did not inhbit
pfKASIII (IC(50) > 330 &mgr;M), but three structurally similar substituted
1,2-dithiole-3-one compounds did inhibit pfKASIII with IC(50) values between
0.53 &mgr;M and 10.4 &mgr;M. These compounds also inhibited the growth of P.
falciparum in culture.
J Vector Ecol 2002 Dec;27(2):222-9
Selection for pyrethroid resistance in a colony of Anopheles minimus
species A, a malaria vector in Thailand.
Chareonviriyaphap T, Rongnoparut P, Juntarumporn P.
Department of Entomology, Faculty ofAgriculture, Kasetsart University, Bangkok
This study tested susceptibilities of Anopheles minimus mosquitoes to
deltamethrin during each of 19 generations (although technical problems excluded
selective pressure experiments during generations 11-13). The ultimate goal was
to establish a pyrethroid resistant colony of this important malaria vector in
Thailand. Resistance was selected for by exposing, using the World Health
Organization test protocol, sequential generations of An. minimus females to
LD50 and LT50 values of deltamethrin. The LD50 and LD90 values were determined
for populations from each subsequent generation by probit analysis and
significant increases (chi-square test, P>0.01) occurred from one generation to
the next. There was approximately a 22-fold increase in the LD50 and a 27-fold
increase in LD90 when the F10 generation was compared to the parent colony (F1).
Similarly, the LT50 and LT90 values were also increased during selection
experiments during generations 14-19. There was roughly a 3-fold increase in
susceptibility of F19 females compared to F14 females. In addition, deltamethrin
conferred a cross-resistance to DDT in the selected colony. Baseline information
from these experiments will serve as a guide for future studies on
susceptibilities of wild An. minimus populations in Thailand.