7.01.2008
Forget the meteorites - it was insects that did for the dinosaurs [Guardian - United Kingdom ] — (English)
In the gut of one biting insect preserved in amber - fossilised tree sap - from that era, the team has found the pathogen that causes the parasitic disease leishmaniasis, and in another they found a type of malaria parasite that infects birds and lizards. By inspecting fossilised dinosaur faeces, the team also found parasitic microbes that are carried by insects...
Risk factors for house-entry by malaria vectors in a rural town and satellite villages in The Gambia [Malaria Journal 2008, 7:2 (7 January 2008)] — (English)
This study demonstrates that the risk of malaria transmission is greatest in rural areas, where large numbers of people sleep in houses made of mud blocks, where the eaves are open, horses are not tethered nearby and where churai is not burnt at night. These factors need to be considered in the design and analysis of intervention studies designed to reduce malaria transmission in The Gambia and other parts of sub-Saharan Africa...
Protein increases malaria deaths in mice [The Daily Utah Chronicle] — (English)
A new study shows that genetically-engineered mice lacking a certain protein have a greater chance of surviving malaria...
'Nothing But Nets" raises funds for mosquito nets [Sioux City Journal - Sioux City,IA,USA] — (English)
People attending the Morningside College and Briar Cliff University women's and men's basketball games Jan. 12, at Rosen Verdoorn Sports Center on the Morningside campus will have an opportunity to help prevent the spread of malaria in Africa...
5.01.2008
New Task: Malaria drug might inhibit some cancers [Science News - USA] — (English)
New studies in mice show that chloroquine may indeed prevent Burkitt's lymphoma and also a rare disease called ataxia telangiectasia that can lead to leukemia...
4.01.2008
'Knockout' Surprise: Mice More Likely To Survive Malaria When Key Gene Is Disabled In White Blood Cell [Science Daily (press release) - USA] — (English)
Mice that lack a molecule found in a type of white blood cell had a significantly higher survival rate from malaria than those in which the molecule is present, an international study led by University of Utah researchers has found...
Death of grandson of anti-apartheid hero caused by cerebral malaria [International Herald Tribune - France] — (English)
A grandson of the late anti-apartheid hero Walter Sisulu died of cerebral malaria, the government said Friday...
Malaria cure: The journey so far [Nigerian Tribune - Ibadan,Nigeria] — (English)
The cost implication of malaria on health and the economy is tremendous and scientists are bent on getting a cure for it, reports Sade Oguntola...
3.01.2008
Malaria risk 'higher this year' [BBC News - UK] — (English)
Southern Africa could be facing a heightened risk of malaria this year, the World Health Organization warns...
Upstream Biosciences to Collaborate With Leading Canadian Public Health Lab to Test Its Novel Agents Against Malaria [FOX News - USA] — (English)
Upstream Biosciences Inc. (OTCBB: UPBS) today announced that it has entered into a collaboration with the Provincial Laboratory for Public Health (or ProvLab) in Alberta, Canada to begin in vitro testing of Upstream's novel compounds for the potential treatment of malaria. According to the World Health Organization (WHO), an estimated 500 million people become severely ill with malaria and more than one million people die of the disease each year...
Mosquito Nets versus Malaria [Spiegel - Germany ] — (English)
Africa's best hope to fight malaria is the wide distribution of mosquito-repelling bed nets. But who best serves that need: the public sector or private interests?...
Host erythrocyte polymorphisms and exposure to Plasmodium falciparum in Papua New Guinea [Malaria Journal 2008, 7:1 (3 January 2008)] — (English)
Effects of several human erythrocyte polymorphisms on parasite prevalence and density in a survey of asymptomatic children in PNG. None of the erythrocyte polymorphisms had a significant effect on prevalence or density, and these results support previous work suggesting that alpha-thalassaemia, CR1 and ABO protect against severe malaria via mechanisms that do not directly affect parasite density...
The one to watch in 2008 [New Statesman - London,England,UK] — (English)
Malaria kills thousands each day, mainly in the world's poorest countries. At a research centre in Mozambique, the work of one man, Pedro Alonso, offers hope...
2.01.2008
Making mosquitoes completely free of parasites is essential to preventing malaria [Imperial College London - London,UK] — (English)
Making sure mosquitoes are completely free from malaria parasites is one of the more effective ways to fight the transmission of malaria, says new research published today (Friday 28 December) in PLoS Pathogens...
Charity vs. Capitalism in Africa [BusinessWeek - USA] — (English)
Africa's best hope to fight malaria is the wide distribution of mosquito-repelling bed nets. But who best serves that need: the public sector or private interests?...
SOUTHERN AFRICA: WHO warns of high levels of malaria [IRINNEWS] — (English)
The World Health Organisation (WHO) is warning of the possibility of above average malaria transmission levels in the region this season prompted by unusually high wet conditions because of the climate phenomenon called La Niña...
1.01.2008
Shepaug star raises awareness about malaria in Africa [Danbury News Times - Danbury,CT,USA] — (English)
Needing a year-long senior project, Samantha Steinmetz's problem was solved last spring when she was shown a Sports Illustrated article written by columnist Rick Reilly about a burgeoning charity called Nothing But Nets...
Primary Health for All [Scientific American] — (English)
Ten resolutions could globally ensure a basic human right at almost unnoticeable cost
By Jeffrey D. Sachs...
31.12.2007
RPI scientist fights malaria at the source [Albany Times Union - Albany,NY,USA] — (English)
A Rensselaer Polytechnic Institute scientist has discovered a fact about mosquitoes that may turn the treatment model for malaria upside down. But instead of treating humans infected by malaria, Robert Lindhardt wants to treat infected mosquitoes...
Vaccine for Malaria [WKYC News - United States ] — (English)
Case Western Reserve University School of Medicine researchers have evidence a vaccine against Malaria will reduce infection and disease rates.
CLEVELAND ? In the middle of winter it's difficult to think about a disease usually found in the tropics, however, researchers at the Case Western Reserve University School of Medicine?s Center for Global Health & Diseases published data potentially impacting the three billion people exposed to malaria every year...
30.12.2007
Seduced by 'winnable war' donors throw money at malaria [Monsters and Critics.com - Glasgow,UK] — (English)
In Belalanda, a small village of reed huts in south-west Madagascar women in wrap dresses, their faces smeared with a skin-lightening face pack, file away from the local health clinic with packages on their heads...
29.12.2007 and earlier
Fever as a Cause of Hypophosphatemia in Patients with Malaria [PLoS ONE. 2007 Dec 26;2(12):e1380] — (English)
Hypophosphatemia occurs in 40 to 60% of patients with acute malaria, and in many other conditions associated with elevations of body temperature. To determine the prevalence and causes of hypophosphatemia in patients with malaria, we retrospectively studied all adults diagnosed with acute malaria during a 12-year period. To validate our findings, we analyzed a second sample of malaria patients during a subsequent 10-year period. Serum phosphorus correlated inversely with temperature (n = 59, r = −0.62; P<0.0001), such that each 1°C increase in body temperature was associated with a reduction of 0.18 mmol/L (0.56 mg/dL) in the serum phosphorus level (95% confidence interval: −0.12 to −0.24 mmol/L [−0.37 to −0.74 mg/dL] per 1°C). A similar effect was observed among 19 patients who had repeat measurements of serum phosphorus and temperature. In a multiple linear regression analysis, the relation between temperature and serum phosphorus level was independent of blood pH, PCO2, and serum levels of potassium, bicarbonate, calcium, albumin, and glucose. Our study demonstrates a strong inverse linear relation between body temperature and serum phosphorus level that was not explained by other factors known to cause hypophosphatemia. If causal, this association can account for the high prevalence of hypophosphatemia, observed in our patients and in previous studies of patients with malaria. Because hypophosphatemia has been observed in other clinical conditions characterized by fever or hyperthermia, this relation may not be unique to malaria. Elevation of body temperature should be added to the list of causes of hypophosphatemia...
Sterile Protection against Malaria Is Independent of Immune Responses to the Circumsporozoite Protein [PLoS ONE. 2007 Dec 26;2(12):e1371] — (English)
We conclude that other pre-erythrocytic parasite antigens, possibly hitherto uncharacterised, can be targeted to induce sterile immunity against malaria. From a broader perspective, our results raise the question as to whether immunodominant parasite antigens should be the favoured targets for vaccine development...
Towards a Vaccine against Plasmodium vivax Malaria [PLoS Med. 2007 Dec 18;4(12):e350] — (English)
There is little doubt that effective interventions against Plasmodium vivax are needed. An estimated 2.6 billion people live in areas endemic for P. vivax, and P. vivax carries a substantial burden of disease with 50–70 million clinical episodes each year...
Hemolytic C-Type Lectin CEL-III from Sea Cucumber Expressed in Transgenic Mosquitoes Impairs Malaria Parasite Development [PLoS Pathogens Volume 3 Issue 12 December 2007] — (English)
The midgut environment of anopheline mosquitoes plays an important role in the development of the malaria parasite. Using genetic manipulation of anopheline mosquitoes to change the environment in the mosquito midgut may inhibit development of the malaria parasite, thus blocking malaria transmission. Here we generate transgenic Anopheles stephensi mosquitoes that express the C-type lectin CEL-III from the sea cucumber, Cucumaria echinata, in a midgut-specific manner. CEL-III has strong and rapid hemolytic activity toward human and rat erythrocytes in the presence of serum. Importantly, CEL-III binds to ookinetes, leading to strong inhibition of ookinete formation in vitro with an IC50 of 15 nM. Thus, CEL-III exhibits not only hemolytic activity but also cytotoxicity toward ookinetes. In these transgenic mosquitoes, sporogonic development of Plasmodium berghei is severely impaired. Moderate, but significant inhibition was found against Plasmodium falciparum. To our knowledge, this is the first demonstration of stably engineered anophelines that affect the Plasmodium transmission dynamics of human malaria. Although our laboratory-based research does not have immediate applications to block natural malaria transmission, these findings have significant implications for the generation of refractory mosquitoes to all species of human Plasmodium and elucidation of mosquito–parasite interactions...
The Edge of Evolution [Zeal For Truth - Eugene,OR,USA] — (English)
Throughout human history, malaria has remained a deadly killer. Even today, malaria kills approximately one million people each year. The epic battle between man and malaria offers us insight into evolution in action. We invent drugs which work for a time, and the malaria parasite develops immunities to the drugs. Curiously, malaria develops resistance to some kinds of drugs faster than to others. Some drugs are effective only a few years before malaria evolves a defense. Others, like chloroquine, were effective against malaria for many years until the inevitable resistant strains appeared. Inevitable resistance? Perhaps not. There is one mechanism against which malaria has evolved no resistance, even after thousands of years: sickle cell disease...
Immtech loses half its value on study's end [Chicago Sun-Times - United States] — (English)
Immtech Pharmaceuticals Inc. said tests of its drug for malaria and sleeping sickness were halted after participants in a trial developed liver abnormalities, Bloomberg News reported...
Sea cucumber 'new malaria weapon' [BBC News - UK] — (English)
Sea cucumbers could provide a potential new weapon to block transmission of the malaria parasite, a study suggests...
Malaria Drug Promising Against Cancer [U.S. News & World Report - Washington,DC,USA] — (English)
60-year-old drug chloroquine eliminated certain malignancies in mice, researchers say...
McGill researchers report breakthrough in rapid malaria detection [EurekAlert (press release) - Washington,DC,USA] — (English)
A research team led by Dr. Paul Wiseman of the Departments of Physics and Chemistry at McGill University has developed a radically new technique that uses lasers and non-linear optical effects to detect malaria infection in human blood, according to a study published in the Biophysical Journal. The researchers say the new technique holds the promise of simpler, faster and far less labour-intensive detection of the malaria parasite in blood samples...
Drive against malaria [Calcutta Telegraph - Calcutta,India] — (English)
The North East Craft and Rural Development Organisation (Necardo), an NGO that has been working in the villages of Dhubri in Lower Assam, has embarked on a drive to eradicate malaria...
Workshop on malaria control held at Breman Asikuma [Joy Online - Accra,Ghana] — (English)
Humanitarian Foundation, an NGO based in Asikuma-Odoben-Brakwa District, in collaboration with Ghana Health Service and National Malaria Control Programme, has organized a day's workshop on malaria awareness for some health personnel, assembly members and religious organisations in the district...
Articles requiring subscription
Tolérance et efficacité de la méfloquine dans le traitement de première intention de l’accès palustre simple à P. falciparum d’importation chez l’enfant [Pathologie Biologie, In Press, Corrected Proof, Available online 4 January 2008] — (Français)
Trente-cinq enfants ont été traités par méfloquine en première intention, dont 13 (37 %) n’avaient pas de vomissements avant ou pendant la consultation aux urgences et 22 (63 %) avaient des vomissements initiaux. Tous ces enfants ont évolué favorablement sauf deux qui ont été traités par quinine IV en raison de vomissements secondaires. Ces deux enfants n’avaient reçu ni antiémétique, ni repas léger...
Cultivation of Plasmodium vivax [Trends in Parasitology, In Press, Corrected Proof, Available online 3 January 2008] — (English)
Establishment of a continuous line of Plasmodium vivax parasite is crucial to understand the parasite's biology; however, this has not yet been achieved. Beginning in the 19th century, there were several efforts to cultivate this malaria parasite but without much success until the late 1980s. In addition, to date, only minor modifications of the methodology have been investigated, which has resulted in extending the cultivation period to around four weeks by supplying reticulocytes obtained from normal blood or rare hemochromatotic blood. However, the use of laboratory-produced erythroblasts to cultivate P. vivax enables maintenance of a continuous line of the parasite stably in the laboratory. Here, we summarize and compare the available methodologies and conditions for the in vitro cultivation of P. vivax...
"He will ask why the child gets sick so often": The gendered dynamics of intra-household bargaining over healthcare for children with fever in the Volta Region of Ghana [Social Science & Medicine, In Press, Corrected Proof, Available online 31 December 2007 ] — (English)
This paper explores the gendered dynamics of intra-household bargaining around treatment seeking for children with fever revealed through two qualitative research studies in the Volta Region of Ghana, and discusses the influence of different gender and health discourses on the likely policy implications drawn from such findings. Methods used included focus group discussions, in-depth and critical incidence interviews, and Participatory Learning and Action methods. We found that treatment seeking behaviour for children was influenced by norms of decision-making power and ‘ownership’ of children, access to and control over resources to pay for treatment, norms of responsibility for payment, marital status, household living arrangements, and the quality of relationships between mothers, fathers and elders. However, the implications of these findings may be interpreted from different perspectives. Most studies that have considered gender in relation to malaria have done so within a narrow biomedical approach to health that focuses only on the outcomes of gender relations in terms of the (non-)utilisation of allopathic healthcare. However, we argue that a ‘gender transformatory’ approach, which aims to promote women's empowerment, needs to include but go beyond this model, to consider broader potential outcomes of intra-household bargaining for women's and men's interests, including their livelihoods and ‘bargaining positions’...
Can transgenic mosquitoes afford the fitness cost [Trends in Parasitology, In Press, Corrected Proof, Available online 27 December 2007 ] — (English)
In a recent study, SM1-transgenic Anopheles stephensi, which are resistant partially to Plasmodium berghei, had higher fitness than non-transgenic mosquitoes when they were maintained on Plasmodium-infected blood. This result should be interpreted cautiously with respect to malaria control using transgenic mosquitoes because, despite the evolutionary advantage conferred by the transgene, a concomitant cost prevents it from invading the entire population. Indeed, for the spread of a resistance transgene in a natural situation, the transgene's fitness cost and the efficacy of the gene drive will be more crucial than any evolutionary advantage...
Antimalarial resistance and DHFR/DHPS genotypes of Plasmodium falciparum three years after introduction of sulfadoxine–pyrimethamine and amodiaquine in rural Tanzania [Transactions of the Royal Society of Tropical Medicine and Hygiene, In Press, Corrected Proof, Available online 21 December 2007] — (English)
We assessed the efficacy of sulfadoxine–pyrimethamine (SP) and amodiaquine (AQ) and DHFR/DHPS genotypes of Plasmodium falciparum in rural Tanzania, 3 years after their introduction as first- and second-line treatments for uncomplicated malaria, respectively. Underfive children with uncomplicated malaria were given standard treatments of either SP (n = 66) or AQ (n = 30) and treatment outcomes after 14 and 28 days were determined. Total treatment failure of 18 and 42.5% was observed for SP on days 14 and 28, respectively. For AQ, total treatment failure of 27 and 53% was found on day 14 and 28, respectively. On day 14, significantly lower SP total treatment failures were observed in 2004 compared with results from a study conducted in 1999 in the same location. No relationship was detected between clinical outcome and DHFR/DHPS genotypes, but the point mutation prevalence in parasites was higher than in 1999. Pre-treatment blood levels of SP were detected in a quarter of the study children: less than expected. We report unacceptably high levels of total treatment failures, both for first- and second-line treatments for uncomplicated malaria in Tanzania 3 years after their introduction, supporting the decision to replace them with artemisinin-based combination therapy...
DEET microencapsulation: a slow-release formulation enhancing the residual efficacy of bed nets against malaria vectors [Transactions of the Royal Society of Tropical Medicine and Hygiene, In Press, Corrected Proof, Available online 20 December 2007] — (English)
Textile materials treated with synthetic repellents have the potential to provide protection against insect disease vectors but lack the residual activity necessary to achieve a prolonged effect or to be cost-effective. DEET MC is a formulation of DEET (N,N diethyl-m-toluamide) in which the repellent is gradually released from a capsule that binds the repellent. An experiment carried out on DEET-treated mosquito netting showed that the formulation repels, inhibits blood-feeding and kills mosquitoes for a period of at least 6 months under laboratory conditions. Such formulations may have the potential for use on nets against pyrethroid-resistant mosquitoes or on clothing or bedding materials distributed in disasters, emergencies or refugee camp situations...
Anemia and iron deficiency in pregnant Ghanaian women from urban areas [International Journal of Gynecology & Obstetrics, In Press, Corrected Proof, Available online 19 December 2007] — (English)
Although anemia and iron deficiency remain substantial problems in pregnant Ghanaian women from urban areas, their prevalence is less than previously reported...
Dihydroorotase of human malarial parasite Plasmodium falciparum differs from host enzyme [Biochemical and Biophysical Research Communications, In Press, Uncorrected Proof, Available online 17 December 2007] — (English)
Plasmodium falciparum, the causative agent of human malaria, is totally dependent on de novo pyrimidine biosynthetic pathway. A gene encoding P. falciparum dihydroorotase (pfDHOase) was cloned and expressed in Escherichia coli as monofunctional enzyme. PfDHOase revealed a molecular mass of 42 kDa. In gel filtration chromatography, the major enzyme activity eluted at 40 kDa, indicating that it functions in a monomeric form. This was similarly observed using the native enzyme purified from P. falciparum. Interestingly, kinetic parameters of the enzyme and inhibitory effect by orotate and its 5-substituted derivatives parallel that found in mammalian type I DHOase. Thus, the malarial enzyme shares characteristics of both type I and type II DHOases. This study provides the monofunctional property of the parasite DHOase lending further insights into its differences from the human enzyme which forms part of a multifunctional protein...
A conserved U-rich RNA region implicated in regulation of translation in Plasmodium female gametocytes [Nucleic Acids Res. 2007 Dec 23] — (English)
Translational repression (TR) plays an important role in post-transcriptional regulation of gene expression and embryonic development in metazoans. TR also regulates the expression of a subset of the cytoplasmic mRNA population during development of fertilized female gametes of the unicellular malaria parasite, Plasmodium spp. which results in the formation of a polar and motile form, the ookinete. We report the conserved and sex-specific regulatory role of either the 3'- or 5'-UTR of a subset of translationally repressed mRNA species as shown by almost complete inhibition of expression of a GFP reporter protein in the female gametocyte. A U-rich, TR-associated element, identified previously in the 3'-UTR of TR-associated transcripts, played an essential role in mediating TR and a similar region could be found in the 5'-UTR shown in this study to be active in TR. The silencing effect of this 5'-UTR was shown to be independent of its position relative to its ORF, as transposition to a location 3' of the ORF did not affect TR. These results demonstrate for the first time in a unicellular organism that the 5' or the 3'-UTR of TR-associated transcripts play an important and conserved role in mediating TR in female gametocytes...
Heterogeneity of malaria prevalence in alluvial gold mining areas in Northern Mato Grosso State, Brazil [Cad Saude Publica. 2007 Dec;23] — (English)
This paper analyzes factors affecting the risk of malaria among individuals working in wildcat gold mining camps (garimpos) in northern Mato Grosso State in the Brazilian Amazon. Historically, such mining camps have the locations with the highest malaria prevalence in the Brazilian Amazon. However, little attention has focused on understanding the disease from the internal perspective of the mining camps themselves, such as the mining population's characteristics and its spatial organization. This paper adopts a stepwise logistic model to identify spatial, occupational-exposure, and cultural factors that affect malaria prevalence. According to the results, differences among individuals working and/or living in the gold mining areas could produce different exposure to the disease and thus to different risk of malaria prevalence. Understanding these differences may provide an important tool for identifying risk profiles in the gold mining and related population and for informing programs for prevention and treatment of malaria in the Amazon...
DDT reintroduction for malaria control: the cost-benefit debate for public health [Cad Saude Publica. 2007 Dec;23(12):2835-2844] — (English)
DDT is a persistent insecticide that was widely used in the world from the 1940s until the 70s, when it was banned in the United States and other countries. Most of its toxic effects are not observed in the acute forms, but particularly after chronic exposure. These long-term issues include reproductive effects, varying according to the time of life in which the individuals were exposed. The aims of the current study were to review the principal toxicological effects of DDT on reproduction, stratifying by physiological periods of exposure, and based on the magnitude of these effects, to discuss the cost-benefit relationship of reintroducing DDT with the specifically defined vector control criteria...
Diversity and evolution of the rhoph1/clag multigene family of Plasmodium falciparum [Mol Biochem Parasitol. 2007 Nov 17] — (English)
A complex of high-molecular-mass proteins (PfRhopH) of the human malaria parasite Plasmodium falciparum induces host protective immunity and therefore is a candidate for vaccine development. Understanding the level of polymorphism and the evolutionary processes is important for advancements in both vaccine design and knowledge of the evolution of cell invasion in this parasite. In the present study, we sequenced the entire open reading frames of seven genes encoding the proteins of the PfRhopH complex (rhoph2, rhoph3, and five rhoph1/clag gene paralogs). We found that four rhoph1/clag genes (clag2, 3.1, 3.2, and 8) were highly polymorphic. Amino acid substitutions and indels are predominantly clustered around amino acid positions 1000–1200 of these four rhoph1/clag genes. An excess of nonsynonymous substitutions over synonymous substitutions was detected for clag8 and 9, indicating positive selection. The McDonald–Kreitman test with a Plasmodium reichenowi orthologous sequence also supports positive selection on clag8. Based on the ratio of interspecific genetic distance to intraspecific distance, the time to the most recent common ancestor of the clag2 and 8 polymorphisms was estimated to be 1.89 and 0.87 million years ago, respectively, assuming divergence of P. falciparum and P. reichenowi 6 million years ago. In addition to a copy number polymorphism, gene conversion events were detected for the rhoph1/clag genes on chromosome 3, which likely play a role in increasing the diversity of each locus. Our results indicate that a high diversity of the PfRhopH1/Clag multigene family is maintained by diversifying selection forces over a considerably long period...
Identification and molecular characterization of a novel protein Saglin as a target of monoclonal antibodies affecting salivary gland infectivity of Plasmodium sporozoites [Insect Mol Biol. 2007 Dec;16(6):711-22] — (English)
In the malaria vector Anopheles gambiae, alternative arrangements of chromosome 2 (2La and 2L+a) vary in relative frequency along clines of aridity, suggesting the action of natural selection on targets within the inversion. Our long term goal of detecting such targets depends in part on the level of genetic exchange between arrangements. Accordingly, we estimated recombination rates on 2L from the backcross progeny of 2La/+a heterokaryotypes and as a control, from 2L+a homokaryotypes. In homokaryotypes, the recombination rate was uniform at ~2.0 centimorgans per megabase (cM/Mb). In heterokaryotypes, recombination within the rearranged region was reduced to < 0.5 cM/Mb, with slightly higher but nevertheless reduced levels (< 1.0 cM/Mb) flanking the rearrangement. Yet, gene exchange was recorded between nearly all markers, including those very near the distal inversion breakpoint. These results suggest that reduced recombination is a necessary but not sufficient mechanism for genetic isolation between alternative arrangements, and that the targets of natural selection can be identified against the different chromosomal backgrounds...
Genetic exchange in 2La inversion heterokaryotypes of Anopheles gambiae [Insect Molecular Biology, Volume 16 Issue 6 Page 703-709, December 2007 ] — (English)
In the malaria vector Anopheles gambiae, alternative arrangements of chromosome 2 (2La and 2L+a) vary in relative frequency along clines of aridity, suggesting the action of natural selection on targets within the inversion. Our long term goal of detecting such targets depends in part on the level of genetic exchange between arrangements. Accordingly, we estimated recombination rates on 2L from the backcross progeny of 2La/+a heterokaryotypes and as a control, from 2L+a homokaryotypes. In homokaryotypes, the recombination rate was uniform at ~2.0 centimorgans per megabase (cM/Mb). In heterokaryotypes, recombination within the rearranged region was reduced to < 0.5 cM/Mb, with slightly higher but nevertheless reduced levels (< 1.0 cM/Mb) flanking the rearrangement. Yet, gene exchange was recorded between nearly all markers, including those very near the distal inversion breakpoint. These results suggest that reduced recombination is a necessary but not sufficient mechanism for genetic isolation between alternative arrangements, and that the targets of natural selection can be identified against the different chromosomal backgrounds...
Evidence for late Pleistocene population expansion of the malarial mosquitoes, Anopheles arabiensis and Anopheles gambiae in Nigeria [Medical and Veterinary Entomology, Volume 21 Issue 4 Page 358-369, December 2007] — (English)
Anopheles gambiae Giles s.s. and Anopheles arabiensis Patton (Diptera: Culicidae) are major vectors of malaria in Nigeria. We used 1115 bp of the mitochondrial COI gene to assess their population genetic structures based on samples from across Nigeria (n = 199). The mtDNA neighbour-joining tree, based on FST estimates, separated An. gambiae M and S forms, except that samples of An. gambiae M from Calabar clustered with all the An. gambiae S form. Anopheles arabiensis and An. gambiae could be combined into a single star-shaped, parsimonious haplotype network, and shared three haplotypes. Haplotype diversity values were high in An. arabiensis and An. gambiae S, and intermediate in An. gambiae M; all nucleotide diversities were relatively low. Taken together, patterns of haplotype diversity, the star-like genealogy of haplotypes, five of seven significant neutrality tests, and the violation of the isolation-by-distance model indicate population expansion in An. arabiensis and An. gambiae S, but the signal was weak in An. gambiae M. Selection is supported as an important factor shaping genetic structure in An. gambiae in Nigeria. There were two geographical subdivisions in An. arabiensis: one included all southern localities and all but two central localities; the other included all northern and two central localities. Re-analysing an earlier microsatellite dataset of An. arabiensis using a Bayesian method determined that there were two distinctive clusters, northern and southern, that were fairly congruent with the mtDNA subdivisions. There was a trend towards decreasing genetic diversity in An. arabiensis from the northern savannah to the southern rainforest that corroborated previous data from microsatellites and polytene chromosomes...
Population dynamics of pest mosquitoes and potential malaria and West Nile virus vectors in relation to climatic factors and human activities in the Camargue, France [Medical and Veterinary Entomology, Volume 21 Issue 4 Page 350-357, December 2007] — (English)
The Camargue is an extensive wetland in the southeast of France, which is highly influenced by human activities. Large ponds, marshes and irrigated fields provide abundant potential breeding sites for mosquitoes. mosquitoes, which are important in terms of the nuisance they cause to people and animals, the limitations they impose on tourism and their potential threat to human health. Several of the mosquito species present are potential vectors of malaria and West Nile virus. Therefore, the population dynamics of these species were monitored over an entire breeding season during March–October 2005. Mosquito populations were sampled in two study areas once every 2 weeks, using CDC light traps baited with CO2. Sixteen species were collected. The majority (98.7%) of the catch were Aedes caspius (Pallas) (Diptera: Culicidae), Culex modestus (Ficalbi), Culex pipiens L. and Anopheles hyrcanus (Pallas). The population dynamics of these species varied considerably in relation to the species’ biology, climatic conditions (rainfall, temperature and season), water management, implementation of mosquito control campaigns and landscape use...
Abundance, biting behaviour and parous rate of anopheline mosquito species in relation to malaria incidence in gold-mining areas of southern Venezuela [Medical and Veterinary Entomology, Volume 21 Issue 4 Page 339-349, December 2007] — (English)
A longitudinal entomological and epidemiological study was conducted in five localities of southern Venezuela between January 1999 and April 2000 to determine the abundance, biting behaviour and parity of anopheline mosquitoes (Diptera: Culicidae) in relation to climate variables and malaria incidence. A total of 3685 female anopheline mosquitoes, representing six species, were collected. The most abundant species were Anopheles marajoara Galvão & Damasceno (60.7%) and Anopheles darlingi Root (35.1%), which together represented 95.8% of the total anophelines collected. Abundance and species distribution varied by locality. Malaria prevalence varied from 12.5 to 21.4 cases per 1000 population. Transmission occurred throughout the year; the annual parasite index (API) for the study period was 813.0 cases per 1000 population, with a range of 71.6−2492 per 1000 population, depending on locality. Plasmodium vivax (Grassi & Feletti) (Coccidia: Plasmodiidae) accounted for 78.6% of cases, Plasmodium falciparum (Welch) for 21.4% and mixed infections (Pv + Pf) for < 0.1%. Anopheles marajoara and An. darlingi were more abundant during the rainy season (April–September). There was no significant correlation (P > 0.05) between mosquito abundance and rainfall. Correlations between malaria incidence by parasite species and mosquito abundance were not significant (P > 0.05). Monthly parous rates were similar for An. marajoara and An. darlingi throughout the year, with two peaks that coincided with the dry−rainy transition period and the period of less rain. Peaks in the incidence of malaria cases were observed 1 month after major peaks in biting rates of parous anophelines. Anopheles darlingi engages in biting activity throughout the night, with two minor peaks at 23.00–00.00 hours and 03.00–04.00 hours. Anopheles marajoara has a different pattern, with a biting peak at 19.00−21.00 hours and 76.6% of biting occurring before midnight. Although both vectors bite indoors and outdoors, they showed a highly significant (P < 0.01) degree of exophagic behaviour. The present study constitutes the first effort to characterize the bionomics of anophelines in malaria endemic foci in different ecological situations in relation to malaria transmission in southern Venezuela and to provide relevant information to be considered when planning and implementing vector control programmes...
Platelet-Induced Clumping of Plasmodium falciparum–Infected Erythrocytes from Malawian Patients with Cerebral Malaria—Possible Modulation In Vivo by Thrombocytopenia [The Journal of Infectious Diseases 2008;197:72–78] — (English)
Platelets may play a role in the pathogenesis of human cerebral malaria (CM), and they have been shown to induce clumping of Plasmodium falciparum–parasitized red blood cells (PRBCs) in vitro. Both thrombocytopenia and platelet-induced PRBC clumping are associated with severe malaria and, especially, with CM. In the present study, we investigated the occurrence of the clumping phenomenon in patients with CM by isolating and coincubating their plasma and PRBCs ex vivo. Malawian children with CM all had low platelet counts, with the degree of thrombocytopenia directly proportional to the density of parasitemia. Plasma samples obtained from these patients subsequently induced weak PRBC clumping. When the assays were repeated, with the plasma platelet concentrations adjusted to within the physiological range considered to be normal, massive clumping occurred. The results of this study suggest that thrombocytopenia may, through reduction of platelet-mediated clumping of PRBCs, provide a protective mechanism for the host during CM...
Prepared in cooperation with WHO ANGOLA INFO.
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