Library Malaria Bulletin No. 23: October 5-18, 2001
Sciences and Malaria
Evidence Base for Interventions to Reduce Malaria Mortality in
Low and Middle Income Countries. S. Meek, J. Hill, J.
Evidence Base for Interventions to Reduce Under Five Mortality
in Low and Middle Income Countries. H. Gelband, S.
World Health Organ 2001;79(9):869-74
- Global public
goods and health: taking the agenda forward.
Kaul I, Faust M.
Office of Development Studies (ODS), United Nations
Development Programme (UNDP), 336 East 45th St, 4th Floor,
New York, USA.
Email: [email protected]
We examined recent special health initiatives to control
HIV/AIDS, malaria, and tuberculosis, and make four policy
recommendations for improving the sustainability of such
initiatives. First, international cooperation on health
should be seen as an issue of global public goods that
concerns both poor and rich countries. Second, national
health and other sector budgets should be tapped to ensure
that global health concerns are fully and reliably funded;
industrialized countries should lead the way. Third, a
global research council should be established to foster more
efficient health-related knowledge management. Fourth,
managers for specific disease issues should be appointed, to
facilitate policy partnerships. Policy changes in these
areas have already begun and can provide a basis for further
Med Trop (Mars) 2001;61(1):91-8
- An evidence-based
vector control strategy for military deployments: the
British Army experience.
Croft AM, Baker D, von Bertele MJ.
Surgeon General's Department, Ministry of Defence,
Whitehall, London SW1A 2HB, UK.
Email: [email protected]
- We describe the British Army's
current strategy for controlling arthropod vectors of
disease during overseas deployments. Military commanders and
medical officers have different, but complementary
responsibilities in achieving vector control. In this paper
we define a hierarchy of evidence-based vector control
guidelines. Field guidelines must be based on the best
available research evidence, preferably that derived from
pragmatic randomised controlled trials (RCTs), and from
systematic reviews of trials. Assessing the effectiveness of
different vector control measures involves a trade-off
between the relative benefits and harm of different
technology options. There is compelling scientific evidence
that bed nets and screens treated with a pyrethroid
insecticide are highly effective in protecting against
nocturnally active, anthropophilic arthropods (including
ectoparasites), and will reduce the incidence of malaria,
leishmaniasis, lymphatic filariasis and Chagas' disease.
Etofenprox and deltamethrin are the safest pyrethroids, and
permethrin the least safe. Vector control strategies of
probable effectiveness are the use of insecticide-treated
clothing, the wearing of protective clothing, and the
correct use of DEET-based topical insect repellents. Aerosol
insecticides are of debatable effectiveness. Other effective
vector control measures, of limited usefulness during
deployments, include electric fans, mosquito coils/vaporising
mats, and smoke. "Biological" vector control
measures, and insect buzzers/electrocuters are ineffective.
Practical insect avoidance measures, based on an
understanding of vector biology, complete the military
vector-control arsenal. We conclude that practical insect
avoidance measures, combined with pyrethroid-treated nets
and clothing, and DEET-based topical repellents, can achieve
almost 100% protection against biting arthropods.
Med Trop (Mars) 2001;61(1):67-76
prevention and control in the United States military.
Uniformed Service, University of Health Sciences, Department
of Preventive Medicine and Biometrics, 4301 Jones Bridge
Road, Bethesda, MD 20814, USA. [email protected]
Malaria continues to be a serious threat to deployed
military forces in many areas of the World. United States
experiences during, and lessons learned from, World War II,
Viet Nam, and Somalia have significantly changed the way
that military planners, medical and preventive medicine
personnel are facing the malaria challenge. Currently, the
US military has a powerful arsenal of educational courses
and materials, personal protective measures, and malaria
surveillance and control techniques in place to fight
malaria. These new tools will hopefully reduce malaria
morbidity and mortality during military deployments in the
Bull Entomol Res 2001 Oct;91(5):389-411
- Descriptions of
the Anopheles (Cellia) farauti complex of sibling species (Diptera:
Culicidae) in Australia.
Schmidt ER, Foley DH, Hartel GF, Williams GM, Bryan JH.
Tropical Health Program, ACITHN,.
Descriptions of the three sibling species of the Anopheles
farauti complex in Australia, A. farauti Laveran (formerly
A. farauti No. 1), A. hinesorum Schmidt sp.n. (formerly A.
farauti No. 2) and A. torresiensis Schmidt sp.n. (formerly
A. farauti No. 3) are provided. These species form a part of
the punctulatus group, which contains the major malaria
vectors in the southwest Pacific. Morphological markers are
described for adult females, fourth instar larvae and pupae
which identify most specimens, and are presented in keys.
Biochem J 2001 Oct 15;359(Pt 2):295-304
- Identification of
a novel class of insect glutathione S-transferases involved
in resistance to DDT in the malaria vector Anopheles gambiae.
Ranson H, Rossiter L, Ortelli F, Jensen B, Wang X, Roth
CW, Collins FH, Hemingway J.
School of Biosciences, Main College, Cardiff University, PO
Box 915, Cardiff CF10 3TL, Wales, U.K. and Department of
Biological Sciences, University of Notre Dame, PO Box 369,
Notre Dame, IN 46556, U.S.A.
The sequence and cytological location of five Anopheles
gambiae glutathione S-transferase (GST) genes are described.
Three of these genes, aggst1-8, aggst1-9 and aggst1-10,
belong to the insect class I family and are located on
chromosome 2R, in close proximity to previously described
members of this gene family. The remaining two genes,
aggst3-1 and aggst3-2, have a low sequence similarity to
either of the two previously recognized classes of insect
GSTs and this prompted a re-evaluation of the classification
of insect GST enzymes. We provide evidence for seven
possible classes of insect protein with GST-like subunits.
Four of these contain sequences with significant
similarities to mammalian GSTs. The largest novel insect GST
class, class III, contains functional GST enzymes including
two of the A. gambiae GSTs described in this report and GSTs
from Drosophila melanogaster, Musca domestica, Manduca sexta
and Plutella xylostella. The genes encoding the class III
GST of A. gambiae map to a region of the genome on
chromosome 3R that contains a major DDT
gene, suggesting that this gene family is involved in GST-based
resistance in this important malaria vector. In further
support of their role in resistance, we show that the mRNA
levels of aggst3-2 are approx. 5-fold higher in a DDT
resistant strain than in the susceptible strain and
demonstrate that recombinant AgGST3-2 has very high DDT
Med Vet Entomol 2001 Sep;15(3):293-8
anthropophagic behaviour in Anopheles quadriannulatus.
Pates HV, Takken W, Curtis CF, Huisman PW, Akinpelu O,
Laboratory of Entomology, Wageningen Agricultural
University, The Netherlands.
The strongly anthropophilic behaviour of Anopheles gambiae
Giles sensu stricto (Diptera: Culicidae), the most important
malaria vector in Africa, has been demonstrated by field and
laboratory studies. Other members of the An. gambiae complex
express varied degrees of anthropophily. Anopheles
quadriannulatus (Theobald) species A and B are more
zoophilic members of the complex and hence are considered to
be of no medical importance. Olfactometer experiments with
An. quadriannulatus species A have demonstrated attraction
to both human and cow odour. To extend these olfactometer
observations a choice experiment was conducted in an outdoor
cage with a human and a calf as baits, using
laboratory-reared mosquitoes. Anopheles gambiae s.s. (from
Liberia) and two strains of An. quadriannulatus species A (SKUQUA
from South Africa, SANGQUA from Zimbabwe), marked with
different coloured fluorescent powders for identification
purposes, were released simultaneously and given an equal
opportunity to feed on either host. The experiment was
repeated six times. Bloodmeals were identified using the
precipitin technique. Anopheles gambiae s.s. showed highly
anthropophagic behaviour, taking 88% of bloodmeals from the
human host. In contrast, both strains of An. quadriannulatus
fed with equal frequency on the human or the calf; the
response to either host was not significantly different.
These results confirm the olfactometer findings and
demonstrate anthropophagic behaviour not previously recorded
in this species. This finding has implications for
prospective manipulation of host preference for genetic
Med Vet Entomol 2001 Sep;15(3):287-92
- Repellent effects
on Anopheles arabiensis biting humans in Kruger Park, South
Govere J, Braack LE, Durrheim DN, Hunt RH, Coetzee M.
Mpumalanga Department of Health, Nelspruit, South
Email: [email protected]
Distribution of biting sites on the human body by the
malaria vector Anopheles arabiensis Patton (Diptera:
Culicidae) was investigated near a source of mosquitoes in
the Kruger National Park, South Africa. Eight adult male
volunteers (2 teams x 2 pairs of subjects) conducted human
bait collections while seated on camp chairs in the
open-air, wearing only short trousers (no shirt, socks or
shoes). Mosquito collections during 18.30-22.30 hours on
five consecutive nights in April 1998 yielded a total of 679
An. arabiensis females biting subjects with or without their
ankles and feet treated with deet insect repellent (15%
diethyl-3-methylbenzamide, Tabard lotion). On subjects whose
feet and ankles were smeared with repellent, 160 An.
arabiensis females were captured biting in 60 manhours:
88.1% on the legs, 1.4% on the arms and 1.2% on other parts
of the body, but none on the repellent-treated feet or
ankles. On subjects without repellent treatment, 519 An.
arabiensis were caught biting in 60 man-hours: 81.1% on feet
and ankles, 16.4% on legs, 1.4% on arms and 1.2% on the rest
of the body. For individual subjects, the reduction of An.
arabiensis bites ranged from 36.4 to 78.2% (mean protection
69.2%). Results of this study confirm previous findings
that, in this part of South Africa - inhabited only by
wildlife - when people sit outside during the evening An.
arabiensis prefers to bite their lower limbs: 97.5% below
the knees. Overall, the number of bites by the malaria
vector An. arabiensis was reduced more than three-fold (from
26 to 8/person/evening), simply by treating ankles and feet
with a consumer brand of deet repellent. Whether or not this
provides a satisfactory degree of protection against malaria
risk would depend on the malaria sporozoite rate in the
malaria vector population.
Med Vet Entomol 2001 Sep;15(3):267-74
distributions of chromosomal forms of Anopheles gambiae in
West Africa using climate data.
Bayoh MN, Thomas CJ, Lindsay SW.
Department of Biological Sciences, University of Durham, UK.
The mosquito Anopheles gambiae Giles sensu stricto (Diptera:
Culicidae), the principal vector of malaria in West Africa,
comprises several chromosomal forms (e.g. Bissau, Forest,
Mopti, Savanna) associated with climatic zones. Here we show
how climate data can be used to map the geographical
distribution of these chromosomal forms. The climate at 144
sites surveyed for mosquitoes in West Africa between 1971
and 92 was determined using computerized climate surfaces.
Forest and Bissau forms occurred at relatively wet sites:
median annual precipitation 1325 mm and 1438 mm,
respectively, interquartile ranges (IQR) 1144-1858 mm and
1052-1825 mm), whilst the Mopti form was found at dry sites
(annual 938 mm, IQR 713-1047 mm) and the Savanna form at
sites intermediate between the wet and dry forms (annual
1067 mm, IQR 916-1279). Logistic regression analyses of the
climate variables were carried out on a stratified random
sample of half the sites. The resulting models correctly
classified over 80% of the sites for presence or absence of
each chromosomal form. When these models were tested against
excluded sites they were also correct at over 80% of sites.
The combined data produced models that were correct at over
86% of sites. Mean annual precipitation, evapotranspiration,
minimum temperature and maximum temperature were the most
important climate variables correlated with the distribution
of these forms of An. gambiae. We used the logistic models
to map the distribution of each chromosomal form within the
reported range for An. gambiae s.s. in West Africa employing
a geographical information system. Our maps indicate that
each chromosomal form favours particular climate envelopes
in well-defined ecoclimatic zones, although these forms are
sympatric at the edges of their ranges. This study
demonstrates that climate can be used to map the
distribution of chromosomal forms of insects across large
Med Vet Entomol 2001 Sep;15(3):259-66
and behavioural responses of the malaria vector Anopheles
gambiae to human-specific sweat components.
Costantini C, Birkett MA, Gibson G, Ziesmann J, Sagnon
NF, Mohammed HA, Coluzzi M, Pickett JA.
Istituto di Parassitologia, University of Rome, La Sapienza,
Afrotropical malaria vectors of the Anopheles gambiae
complex (Diptera: Culicidae), particularly An. gambiae sensu
stricto, are attracted mainly to human hosts. A major source
of human volatile emissions is sweat, from which key
human-specific components are the carboxylic acids (E)- and
(Z)-3-methyl-2-hexenoic acid and 7-octenoic acid.
Electrophysiological studies on the antennae of An. gambiae
s.s. showed selective sensitivity to these compounds, with a
threshold at 10(-6) g comparable to that of known olfactory
stimulants 1-octen-3-ol, p-cresol, isovaleric acid, and
lower than threshold sensitivity to L-lactic acid and the
synthetic mosquito repellent N,N-diethyltoluamide (DEET). A
combination of the acids released at concentrations >
10(-5) g in wind tunnel bioassays significantly reduced the
response to CO2, the major attractant released by human
hosts, for strains of An. gambiae s.s. originating from East
and West Africa. Field trials with odour-baited entry traps
(OBETs) in Burkina Faso showed that 7-octenoic acid
significantly increased (by 1.7-fold) the catch of females
of An. gambiae sensu lato (comprising two sibling species:
An. arabiensis Patton and An. gambiae s.s.) in OBETs baited
with CO2, whereas combinations of the acids significantly
reduced the catch in CO2-baited traps (by 2.1-fold) and in
whole human odour-baited traps (by 1.5-fold). The pure (E)
and (Z) geometric isomers of 3-methyl-2-hexenoic acid gave
comparable results to the (EIZ) isomer mixture. These
results provide the first experimental evidence that
human-specific compounds affect the behaviour of highly
anthropophilic An. gambiae s.l. mosquitoes. The compounds
appear to inhibit the upwind flight' response to known
long-range attractants, and may serve either to mask' the
attractants present or, more probably, to 'arrest' upwind
flight when mosquitoes arrive at a host under natural
conditions. In the final approach to hosts, vectors are
known to reduce their flight speed and increase their
turning rate, to avoid overshooting the source. In our
experimental apparatus, these changes in flight behaviour
would reduce the number of mosquitoes entering the ports of
the collection devices.
Med Vet Entomol 2001 Sep;15(3):236-48
- Breeding of
Anopheles mosquitoes in irrigated areas of South Punjab,
Herrel N, Amerasinghe FP, Ensink J, Mukhtar M, van der
Hoek W, Konradsen F.
International Water Management Institute, Lahore,
Email: [email protected]
- As part of investigations on
potential linkages between irrigation and malaria
transmission, all surface water bodies in and around three
villages along an irrigation distributary in South Punjab,
Pakistan, were surveyed for anopheline mosquito larvae (Diptera:
Culicidae) from April 1999 to March 2000. Samples were
characterized according to exposure to sunlight, substratum,
presence of vegetation, fauna, inorganic matter and physical
water condition (clear/turbid/foul). Also water temperature,
dissolved oxygen (DO), electroconductivity (EC) and pH of
sites were recorded. A total of 37982 Anopheles larvae of
six morphological types were collected from 2992 samples
taken from irrigation/agricultural and village/domestic
aquatic habitats. Anopheles subpictus Grassi sensu lato was
by far the most abundant (74.3%), followed by An.
culicifacies Giles s.l. (4.1%), An. stephensi Liston s.l.
(2.6%), An. pulcherrimus Theobald (1.8%), An. peditaeniatus
Leicester (0.3%) and An. nigerrimus Giles (0.1%). The four
most abundant species were significantly associated with
waterlogged fields and communal village drinking-water
tanks. Habitat characteristics most correlated with
occurrence of anophelines were the physical water condition
and the absence/presence of fauna, particularly predators.
Occurrence and abundance of Anopheles immatures were not
significantly correlated with water temperature, DO, EC or
pH. Malaria vectors of the Anopheles culicifacies complex
occurred at relatively low densities, mainly in irrigated
and waterlogged fields. In South Punjab, where rainfall is
very low, it should be possible to reduce anopheline
breeding through water management, as larvae develop mainly
in water bodies that are directly or indirectly related to
the extensive canal-irrigation system.
Med Trop (Mars) 2001;61(2):153-7
- OptiMal test
should be used with great caution
[Article in French]
Hernandez E, De Pina JJ, Fabre R, Garrabe E, Raphenon G,
Laboratoire de microbiologie, Hopital d'Instruction des
Armees Begin, Saint-Mande, France.
Email: [email protected]
The OptiMal test is an immuno-chromatographic dipstick test
that permits indiscriminate detection of Plasmodium
falciparum and other species of human malaria. The purpose
of this study was to evaluate the efficacy of the test for
diagnosis of imported malaria. A total of 244 patients with
a presumptive diagnosis of imported malaria in France were
included during the study period. The reference test, i.e.,
combined thick and thin blood films, demonstrated infection
by Plasmodium falciparum in 58 cases, Plasmodium vivax in
12, P. ovale in 8 and Plasmodium malariae in 2. The OptiMal
test detected only 46 of the 55 Plasmodium falciparum cases.
The sensitivity of the test for diagnosis of that species
was 80%, its specificity was 98%, and its positive and
negative predictive values were 95 and 93% respectively.
Parsitemia studies showed poor test reliability for
densities lower than 150/ul. Detection of other species was
accurate in 21 out of 22. The results of this study
demonstrate that the current version of the OptiMal test
should be used with great caution for the diagnosis of
malarial infection in hospital practice.
Chin Med J (Engl) 1999
- Effects of the
configuration of a multi-epitope chimeric malaria DNA
vaccine on its antigenicity to mice.
Jiang Y, Lin C, Yin B, He X, Mao Y, Dong M, Xu P, Zhang
L, Liu B, Wang H.
Chinese Academy of Medical Sciences, Institute of Basic
Medical Sciences, Peking Union Medical College, School of
Basic Medicine, Beijing 100005, China.
OBJECTIVE: Four B and Th cell epitopes were selected from
conservative domain of Plasmodium falciparum antigens to
construct two groups of chimeric malaria DNA vaccines with
different configurations and their antigenicities were
studied. METHODS: The partially synthesized oligonucleotide
was annealed, PCR amplified and cloned into a mammalian cell
expression vector. By using a pair of isocaudamers on the
vector, different single copies of B epitopes were
multiplied and were tenderly stringed into two groups of
chimeric DNA vaccine with different configurations. BALB/c
mice were immunized with these DNA plasmids by either
intramuscular or intradermal injections. RESULTS: The
antisera from the immunized mice tested by ELISA showed that
only the configuration which had a single copy of universal
T helper cell epitope, CS. T3, located at the C terminal of
the multi-copy B cell epitopes induced a high antibody
response. The T helper cell epitope at any other position of
the peptide, or the double T helper cell epitopes configured
with the B cell epitopes did not enhance antibody response,
and some configurations even decreased the humoral response
to a B cell epitope. CONCLUSION: This study demonstrated
that both combination and configuration of the epitope may
affect the antigenicity of a chimeric multiple antigen.
Antimicrob Agents Chemother 2001 Nov;45(11):3171-4
- Reversal of
Chloroquine Resistance in Plasmodium falciparum Using
Combinations of Chemosensitizers.
van Schalkwyk DA, Walden JC, Smith PJ.
Department of Pharmacology, University of Cape Town,
Observatory 7925, South Africa.
Research into chloroquine resistance reversal in Plasmodium
falciparum has revealed a widespread range of functionally
and structurally diverse chemosensitizers. However, nearly
all of these chemosensitizers reverse resistance optimally
only at concentrations that are toxic to humans. Verapamil,
desipramine, and trifluoperazine were shown to potentiate
chloroquine accumulation in a chloroquine-resistant (CQ(r))
strain of P. falciparum, while progesterone, ivermectin, and
cyclosporin A were not shown to potentiate chloroquine
accumulation. The simultaneous use of two or even three of
these chemosensitizers at concentrations within their
therapeutic ranges in humans displayed an additive effect in
potentiating chloroquine accumulation in the CQ(r) strain.
The levels of resistance reversal achieved with these
multiple combinations were comparable to those achieved with
high concentrations of the single agents used to enhance the
activity of chloroquine. No chemosensitizer, whether used
singly or in combination, potentiated any change in
chloroquine accumulation or a shift in the 50% inhibitory
concentration for the chloroquine-sensitive strain. The use
of combinations of chemosensitizers at concentrations not
toxic to humans could effectively reverse chloroquine
resistance without the marked toxicity from the use of a
single agent at high concentrations. This cocktail of
chemosensitizers may serve as a viable treatment to restore
the efficacy of chloroquine in patients with malaria.
Antimicrob Agents Chemother 2001 Nov;45(11):3122-7
- Association of
Genetic Mutations in Plasmodium vivax dhfr with Resistance
to Sulfadoxine-Pyrimethamine: Geographical and Clinical
Imwong M, Pukrittakayamee S, Looareesuwan S, Pasvol G,
Poirreiz J, White NJ, Snounou G.
Faculty of Tropical Medicine, Mahidol University, Bangkok,
Mutations in the Plasmodium falciparum gene (dhfr) encoding
dihydrofolate reductase are associated with resistance to
antifols. Plasmodium vivax, the more prevalent malaria
parasite in Asia and the Americas, is considered antifol
resistant. Functional polymorphisms in the dhfr gene of P.
vivax (pvdhfr) were assessed by PCR-restriction fragment
length polymorphism using blood samples taken from 125
patients with acute vivax malaria from three widely
separated locations, Thailand (n = 100), India (n = 16), and
Madagascar and the Comoros Islands (n = 9). Upon evaluation
of the three important codons (encoding residues 57, 58, and
117) of P. vivax dhfr (pvdhfr), double- or triple-mutation
genotypes were found in all but one case from Thailand
(99%), in only three cases from India (19%) and in no cases
from Madagascar or the Comoros Islands (P < 0.0001). The
dhfr PCR products of P. vivax from 32 Thai patients treated
with the antifolate sulfadoxine-pyrimethamine (S-P) were
investigated. All samples showed either double (53%) or
triple (47%) mutations. Following treatment, 34% of the
patients had early treatment failures and only 10 (31%) of
the patients cleared their parasitemias for 28 days. There
were no significant differences in cure rates, but parasite
reduction ratios at 48 h were significantly lower for
patients whose samples showed triple mutations than for
those whose samples showed double mutations (P = 0.01). The
three mutations at the pvdhfr codons for residues 57, 58,
and 117 are associated with high levels of S-P resistance in
P. vivax. These mutations presumably arose from selection
EMBO J 2001 Oct 15;20(20):5636-5649
- Trafficking and
assembly of the cytoadherence complex in Plasmodium
falciparum-infected human erythrocytes.
Wickham ME, Rug M, Ralph SA, Klonis N, McFadden GI,
Tilley L, Cowman AF.
The Walter and Eliza Hall Institute of Medical Research, PO
Royal Melbourne Hospital, Melbourne 3050, Department of
Biochemistry, La Trobe University, Melbourne and Plant Cell
Biology Research Centre, School of Botany, University of
Melbourne, Melbourne, Australia Corresponding author
Email: [email protected]
After invading human erythrocytes, the malarial parasite
Plasmodium falciparum, initiates a remarkable process of
secreting proteins into the surrounding erythrocyte
cytoplasm and plasma membrane. One of these exported
proteins, the knob-associated histidine-rich protein (KAHRP),
is essential for microvascular sequestration, a strategy
whereby infected red cells adhere via knob structures to
capillary walls and thus avoid being eliminated by the
spleen. This cytoadherence is an important factor in many of
the deaths caused by malaria. Green fluorescent protein
fusions and fluorescence recovery after photobleaching were
used to follow the pathway of KAHRP deployment from the
parasite endomembrane system into an intermediate depot
between parasite and host, then onwards to the erythrocyte
cytoplasm and eventually into knobs. Sequence elements
essential to individual steps in the pathway are defined and
we show that parasite-derived structures, known as Maurer's
clefts, are an elaboration of the canonical secretory
pathway that is transposed outside the parasite into the
host cell, the first example of its kind in eukaryotic
J Eukaryot Microbiol 2001 Sep-Oct;48(5):556-64
antibody recognition of four allelic variants of the
merozoite surface protein-2 (MSP-2) of Plasmodium falciparum.
Tonhosolo R, Wunderlich G, Ferreira MU.
Department of Parasitology, Institute for Biomedical
Sciences, University of Sao Paulo, SP, Brazil.
The merozoite surface protein-2 (MSP-2) is a major vaccine
candidate for the asexual blood stage of Plasmodium
falciparum. MSP-2 is essentially dimorphic, and allelic
families are named after the representative isolates FC27
and IC1. The polymorphic central region contains
immunodominant repeats, which vary in number, length, and
sequence within and between allelic families. We have
examined the antibody recognition of repeat regions from
both MSP-2 allelic families expressed as recombinant fusion
peptides. The results are summarized as follows. (1)
Immunization of mice with the fusion peptides elicited IgG
antibodies that cross-reacted with the native MSP-2 molecule
in an allelic family-specific manner. (2) These mouse
antibodies recognized the recombinant proteins in both a
variant-specific and a family-specific manner, as shown in
inhibition immunoassays. Antibodies raised against the
peptide FC27 seemed to be essentially variant-specific,
since the soluble form of the S20 antigen (a member of FC27
family) had relatively little inhibitory effect on them. (3)
The overall pattern of human IgG antibody responses to MSP-2
in Karitiana Indians, a population continuously exposed to
hypoendemic malaria in the Brazilian Amazon Region, differs
from that described in hyperendemic areas in Africa and
Papua New Guinea in two important features: there was no
clear age-dependent increase in the prevalence and mean
concentration of specific IgG antibodies, and there was no
skewing towards the IgG3 subclass in antibody responses. (4)
The relatively poor correlation between concentrations of
IgG antibodies that are specific for members of the same
allelic family suggests that recognition of MSP-2 peptides
by naturally acquired antibodies was largely
variant-specific in this population. The potential role of
naturally acquired variant-specific antibodies in immune
evasion, by selecting mutant parasites carrying insertions
or deletions of repeat sequences, is briefly discussed.
Int J Parasitol 2001
- Detection of
malaria liver-stages in mice infected through the bite of a
single Anopheles mosquito using a highly sensitive real-time
Bruna-Romero O, Hafalla JC, Gonzalez-Aseguinolaza G, Sano
G, Tsuji M, Zavala F.
Department of Medical and Molecular Parasitology, New York
University School of Medicine, York, NY 10010, New, USA
We describe a highly sensitive real-time PCR to detect and
measure the development of the liver-stages of malaria
parasites in mice infected with sporozoites ranging in
number from 25 to more than 164,000, using the same reaction
conditions. Furthermore, this assay detects and measures
parasite loads in the livers of mice exposed to the bite of
a single malaria-infected Anopheles mosquito. This unique
method should greatly facilitate studies aimed at evaluating
very precisely the efficacy of anti-malarial experimental
drug treatments and vaccination regimens in conditions of
infection resembling those found in the field.
Chin Med J (Engl) 1999 Apr;112(4):349-51
- A diagnostic kit
to screen individuals with glucose-6-phosphate dehydrogenase
defect and its application on anti-malaria spot in the
Nie C, Zhao S.
Department of Parasitology, Medical College of Jinan
University, Guangzhou 510632, China.
OBJECTIVE: To prepare a kit for screening individuals with
glucose-6-phosphate dehydrogenase (G6PD) defect. The kit is
easy to use and to get the fast as well as reliable results.
Especially it is suitable for the anti-malaria spots usually
located in the remote countryside where no electricity is
available. METHODS: The double filter paper method and other
2 techniques, the quantitative method and the single filter
paper method, were used to determine G6PD activity in 70
samples of human erythrocytes. It was found that the results
of the double filter paper method and those of the single
filter paper method in the first 8 hours after the drying of
the blood-soaked filter paper were consistent with those of
the quantitative method. When a piece of blood-soaked paper
is left under room temperature more than 24 hours, G6PD in
the erythrocytes deteriorated spontaneously and consequently
the number of positive cases increased along with the elapse
of time. RESULTS: Satisfactory results were achieved when
the kit was used to screen cases of G6PD defect from 151
farmers who were receiving anti-mararia therapy. The kit was
made according to a technique named "double filter
paper" method. CONCLUSIONS: These findings suggest that
the double filter paper method can reveal the level of G6PD
activity and the results are rapidly obtained when the
method is used on the anti-malaria spot.
Eur J Immunol 2001 Oct;31(10):2970-8
- Direct activation
of dendritic cells by the malaria parasite, Plasmodium
Seixas E, Cross C, Quin S, Langhorne J.
Division of Parasitology, National Institute for Medical
Research, Mill Hill, London, GB.
A primary infection of mice with Plasmodium chabaudi
chabaudi (AS) is characterized by a rapid and marked
inflammatory response. Typically, IL-12, TNF-alpha and IFN-gamma
are produced in the spleen, and are transiently present in
plasma. The cells involved in this early response are
unknown. Here we show that dendritic cells derived from GM-CSF-stimulated
mouse bone marrow cultures produce TNF-alpha within 30 min
of exposure to P.c.chabaudi schizonts. IL-6, IL-12p40 and
p70 follow this. The production of these cytokines was not
dependent on the presence of T cells or NK cells and did not
require CD40. Incubation of dendritic cells with
P.c.chabaudi schizonts also resulted in up-regulation of MHC
class II, CD40 and CD86 but not CD80. In contrast to some
strains of the human parasite, P. falciparum, P.c. chabaudi
(AS) did not inhibit the up-regulation of MHC class II, CD86
or CD40 induced by LPS. Therefore, the erythrocytic stages
of P.c.chabaudi are able to activate dendritic cells
directly. The consequences of such an interaction could be
rapid activation of TH1 cells and induction of immunity, and
in the event of a large response also induction of TNF-alpha
J Cell Sci 2001 Sep;114(Pt 18):3377-86
- Evidence for a
role for a Plasmodium falciparum homologue of Sec31p in the
export of proteins to the surface of malaria
Adisa A, Albano FR, Reeder J, Foley M, Tilley L.
Department of Biochemistry, La Trobe University, Melbourne,
Victoria, Australia. Papua New Guinea Institute of Medical
Research, Goroka, Papua New Guinea.
The malaria parasite, Plasmodium falciparum, spends part of
its life cycle inside the enucleated erythrocytes of its
human host. The parasite modifies the cytoplasm and plasma
membrane of its host cell by exporting proteins beyond the
confines of its own plasma membrane. We have previously
provided evidence that a plasmodial homologue of the COPII
protein, Sar1p, is involved in the trafficking of proteins
across the erythrocyte cytoplasm. We have now characterised
an additional plasmodial COPII protein homologue, namely
Sec31p. Recombinant proteins corresponding to the WD-40 and
the intervening domains of the PfSec31p sequence were used
to raise antibodies. The affinity-purified antisera
recognised a protein with an apparent relative molecular
mass of 1.6x10(5) on western blots of malaria
parasite-infected erythrocytes but not on blots of
uninfected erythrocytes. PfSec31p was shown to be largely
insoluble in nonionic detergent, suggesting cytoskeletal
attachment. Confocal immunofluorescence microscopy of
malaria parasite-infected erythrocytes was used to show that
PfSec31p is partly located within the parasite and partly
exported to structures outside the parasite in the
erythrocyte cytoplasm. We have also shown that PfSec31p and
PfSar1p occupy overlapping locations. Furthermore, the
location of PfSec31p overlaps that of the cytoadherence-mediating
protein PfEMP1. These data support the suggestion that the
malaria parasite establishes a vesicle-mediated trafficking
pathway outside the boundaries of its own plasma membrane -
a novel paradigm in eukaryotic biology.
J Immunol 2001 Oct 15;167(8):4729-37
- Unique T cell
effector functions elicited by Plasmodium falciparum
epitopes in malaria-exposed Africans tested by three T cell
Flanagan KL, Lee EA, Gravenor MB, Reece WH, Urban BC,
Doherty T, Bojang KA, Pinder M, Hill AV, Plebanski M.
Weatherall Institute of Molecular Medicine, University of
Oxford, John Radcliffe Hospital, Headington, Oxford, United
Email: [email protected]
Natural immunity to malaria is characterized by low level
CD4 T cell reactivity detected by either lymphoproliferation
or IFN-gamma secretion. Here we show a doubling in the
detection rate of responders to the carboxyl terminus of
circumsporozoite protein (CS) of Plasmodium falciparum by
employing three T cell assays simultaneously: rapid IFN-gamma
secretion (ex vivo ELISPOT), IFN-gamma secretion after
reactivation of memory T cells and expansion in vitro
(cultured ELISPOT), and lymphoproliferation. Remarkably, for
no individual peptide did a positive response for one T cell
effector function correlate with any other. Thus these CS
epitopes elicited unique T cell response patterns in
malaria-exposed donors. Novel or important epitope responses
may therefore be missed if only one T cell assay is
employed. A borderline correlation was found between anti-CS
Ab levels and proliferative responses, but no correlation
was found with ex vivo or cultured IFN-gamma responses. This
suggested that the proliferating population, but not the IFN-gamma-secreting
cells, contained cells that provide help for Ab production.
The data suggest that natural immunity to malaria is a
complex function of T cell subgroups with different effector
functions and has important implications for future studies
of natural T cell immunity.
J Postgrad Med 2001 Jan-Mar;47(1):24-6
- Severe acute
renal failure in malaria.
Mehta KS, Makwana PD, Torane PP, Satija PS, Shah VB.
Departments of Nephrology and Pathology, B.Y.L. Nair
Hospital and T.N. Medical College, Mumbai, India.
Email: [email protected]
BACKGROUND: We have noticed a recent rise in the incidence
and severity of acute renal failure (ARF) in malaria. AIM:
To study the incidence, severity and outcome of ARF in
malaria. SETTING and DESIGN: It is a retrospective analysis
of data of one year from a tertiary medical centre in a
metropolitan city. MATERIALS AND METHODS: Patients with ARF
and smear positive malaria were evaluated. STATISTICAL
ANALYSIS: Results were expressed as mean, range and standard
deviation. RESULTS: Out of 402 detected smear positive
malaria, 24 had ARF. Eighteen were of the age group 21-40
years. Plasmodium falciparum (PF) was detected in 16,
Plasmodium vivax in three, and mixed infection in five. Non-oliguric
ARF was seen in 14. Eighteen showed severe ARF (Serum
creatinine >5 mg%). Twenty-two patients needed dialysis.
Prolonged ARF lasting for 2-6 weeks was seen in eight.
Seventeen patients recovered completely, while seven showed
fatal combination of disseminated intravascular coagulation
(DIC), acute respiratory distress syndrome (ARDS), severe
ARF and PF malaria. No response was seen to chloroquine and
artesunate given alone and twenty patients required quinine.
CONCLUSION: ARF necessitating dialysis was seen in 92% of
patients with ARF in malaria. PF infection, severe ARF, DIC
and ARDS were poor prognostic factors. Resistance was noted
to both chloroquine and artesunate.
Parasite Immunol 2001 Sep;23(9):491-501
- Nitric oxide and
reactive nitrogen intermediates during lethal and nonlethal
strains of murine malaria.
Nahrevanian H, Dascombe MJ.
School of Biological Sciences, The University of Manchester,
The virulence of Plasmodia depends partly on the strain of
parasite and partly on the host. In this study, Plasmodium
berghei N/13/1A/4/203 caused the death of mice, whereas
Plasmodium chabaudi chabaudi AS was not lethal. Current
opinion is that nitric oxide (NO) and other reactive
nitrogen intermediates (RNI) are produced in several host
organs during malaria to resist infection or produce tissue
damage. NO and RNI production in blood or plasma, brain,
liver and spleen in MF1 mice was investigated during P.
berghei and P. c. chabaudi infection, in order to help
determine whether changes in NO production are beneficial or
detrimental to the host in vivo. NO production was measured
both directly and indirectly as nitrites and nitrates, to
represent RNI. No changes in blood NO were detected in P.
berghei infected mice, but increases were observed in brain,
liver and spleen. In P. c. chabaudi infected mice, rises in
NO concentration were observed in blood and spleen, whereas
a decline in liver NO was seen, but there were no changes in
brain. Liver contained the highest concentration of RNI, but
increasing concentrations were seen in both plasma and
spleen in both P. berghei and P. c. chabaudi infected mice.
These results show that NO and RNI production alters during
murine malaria. The changes depend upon the tissue, the day
of infection, the degree of parasitaemia, the strain of
Plasmodia and the method of measuring NO biosynthesis.
Lethal P. berghei induced NO production in the mid and late
stages of infection in mice when parasitaemia was high,
whereas in nonlethal P. c. chabaudi infection, NO production
was increased in the early and late stages when parasitaemia
was low. These data are consistent with a role for NO in the
protection of the MF1 mouse against Plasmodia. Failure to
clear the parasite is associated with evidence of increased
NO production in brain and liver, which may contribute to
the pathology of malaria, but this hypothesis requires
confirmation from other experimental approaches.
Bull Entomol Res 2001 Aug;91(4):265-73
- Bioassay and
biochemical analyses of insecticide resistance in southern
African Anopheles funestus (Diptera: Culicidae).
Brooke BD, Kloke G, Hunt RH, Koekemoer LL, Temu EA,
Taylor ME, Small G, Hemingway J, Coetzee M.
Medical Entomology, Department of Clinical Microbiology and
Infectious Diseases, School of Pathology of the South
African Institute for Medical Research and the University of
the Witwatersrand, PO Box 1038, Johannesburg, 2000, South
ANOPHELES FUNESTUS: Giles has been implicated as a major
malaria vector in sub-Saharan Africa where pyrethroid
insecticides are widely used in agriculture and public
health. Samples of this species from northern Kwazulu/Natal
in South Africa and the Beluluane region of southern
Mozambique showed evidence of resistance to pyrethroid
insecticides. Insecticide exposure, synergist and
biochemical assays conducted on A. funestus suggested that
elevated levels of mixed function oxidases were responsible
for the detoxification of pyrethroids in resistant
mosquitoes in these areas. The data suggested that this
mechanism was also conferring cross-resistance to the
carbamate insecticide propoxur.
J Chromatogr B Biomed Sci Appl 2001 Sep 25;761(2):255-9
liquid chromatographic determination of diazepam in plasma
of children with severe malaria.
Muchoh SN, Ogutu BR, Newton CR, Kokwar GO.
Kenya Medical Research Institute/Wellcome Trust
Collaborative Research Programme, Nairobi.
Email: [email protected]
A sensitive, selective and reproducible reversed-phase HPLC
method with ultraviolet detection was developed for the
quantification of diazepam in small plasma samples from
children with severe malaria. The method involves plasma
deproteinization with acetonitrile, followed by
liquid-liquid extraction with ethyl acetate-n-hexane.
Diazepam was eluted at ambient temperatures from a
reversed-phase C18 column with an acidic (pH 3.5) aqueous
mobile phase (10 mM KH2PO4-acetonitrile, 69:31, v/v).
Calibration curves in spiked plasma were linear from 10 to
200 ng (r2 > or = 0.99). The limit of detection was 5.0
ng/ml, and relative recoveries at 25 and 180 ng were
>87%. Intra- and inter-assay relative standard deviations
were <15%. There was no interference from drugs commonly
administered to children with severe malaria (phenobarbitone,
phenytoin, chloroquine, quinine, sulfadoxine, pyrimethamine,
halofantrine, cycloguanil, chlorcycloguanil, acetaminophen
and salicylate). This method has been used for monitoring
plasma diazepam concentrations in children with seizures
associated with severe malaria.
Clin Microbiol Rev 2001 Oct;14(4):810-20
- Pathogenesis of
cerebral malaria: recent experimental data and possible
applications for humans.
Lou J, Lucas R, Grau GE.
Department of Surgery, CH-1211 Geneva 14, Switzerland, and
INSERM EMI 0019, UFR Pharmacie, Universite de la
Mediterranee, F-13385 Marseilles, France.
Malaria still is a major public health problem, partly
because the pathogenesis of its major complication, cerebral
malaria, remains incompletely understood. Experimental
models represent useful tools to better understand the
mechanisms of this syndrome. Here, data generated by several
models are reviewed both in vivo and in vitro; we propose
that some pathogenic mechanisms, drawn from data obtained
from experiments in a mouse model, may be instrumental in
humans. In particular, tumor necrosis factor (TNF) receptor
2 is involved in this syndrome, implying that the
transmembrane form of TNF may be more important than the
soluble form of the cytokine. It has also been shown that in
addition to differences in immune responsiveness between
genetically resistant and susceptible mice, there are marked
differences at the level of the target cell of the lesion,
namely, the brain endothelial cell. In murine cerebral
malaria, a paradoxical role of platelets has been proposed.
Indeed, platelets appear to be pathogenic rather than
protective in inflammatory conditions because they can
potentiate the deleterious effects of TNF. More recently, it
has been shown that interactions among platelets,
leukocytes, and endothelial cells have phenotypic and
functional consequences for the endothelial cells. A better
understanding of these complex interactions leading to
vascular injury will help improve the outcome of cerebral
Parasite 2001 Sep;8(3):243-50
- Gametocytaemia in
Senegalese children with uncomplicated falciparum malaria
treated with chloroquine, amodiaquine or sulfadoxine +
Sokhna CS, Trape JF, Robert V.
Laboratoire de Paludologie, UR Paludologie Afrotropicale,
Institut de Recherche pour le Developpement, B.P. 1386
Plasmodium falciparum gametocytaemia was studied in 266
Senegalese children (median 4 years, range 0.5-16) with
uncomplicated malaria treated with chloroquine (CQ),
amodiaquine (AQ) or sulfadoxine + pyrimethamine (SP). The
proportion of resistant infections in vivo to these drugs
was 44%, 16% and 7%, respectively. Gametocytes were counted
by microscopy in thick smears on days 0, 4, 7 and 14 after
treatment. There was a peak of gametocytaemia one week after
treatment; on days 0, 7 and 14 the gametocyte prevalences
were 35%, 73% and 63%, and the geometric means of gametocyte
densities were 1.3, 12.5 and 5.6/microliter of blood. Three
factors were found to influence gametocytaemia: treatment,
efficacy of treatment, and duration of symptoms before
treatment. Gametocyte prevalence and density significantly
appeared higher in children treated with SP than with CQ,
and higher with CQ than with AQ. Gametocyte prevalence and
density were higher in resistant than in sensitive
infections. The period between the appearance of the first
clinical symptoms and treatment was positively and
significantly linked to gametocyte prevalence and density on
days 0 and 4. Early treatment with AQ, against sensitive
infection, was followed by the lowest gametocytaemia. By
contrast, treatment with SP against resistant infection was
followed by the highest gametocytaemia. No clear
relationship was observed between the density of asexual
stages on day 0 and the gametocytaemia at any day between
days 0 and 14. The epidemiological significance of
post-therapeutic gametocytaemia and its possible role in the
spread of resistant parasites are underlined. Solutions are
proposed in order to avoid or reduce this gametocytaemia.