Malaria

Malaria IMC1 membrane skeleton proteins operate autonomously and participate in motility independently of cell shape

Plasmodium IMC1 (inner membrane complex 1) proteins comprise components of the subpellicular network, a lattice of intermediate filaments that form a structural part of the pellicle in the zoite stages of malaria parasites. Family members IMC1a and IMC1b are differentially expressed in sporozoites and ookinetes, respectively, but have functionally equivalent roles affecting cell morphology, strength, motility, and infectivity. Because of the coincident effects of previous imc1 gene disruptions on both zoite shape and locomotion, it has been impossible to ascribe a direct involvement in motility to these proteins. We show here that a third family member, IMC1h, has a distinct differential expression pattern and localizes to the pellicle of both ookinetes and sporozoites. Knock-out of IMC1h mimics the loss-of-function phenotypes of IMC1a and IMC1b in their respective life stages, indicating that IMC1 proteins could be operating co-dependently. By generating double null mutant parasites for IMC1h and IMC1b, we tested this hypothesis: double knock-out exacerbated the phenotypes of the single knock-outs in terms of ookinete strength, motility, and infectivity but did not further affect ookinete morphology. These findings provide the first genetic evidence that IMC1 proteins can function independently of each other and contribute to gliding motility independently of cell shape.

Origin of the human malaria parasite Plasmodium falciparum in gorillas

Plasmodium falciparum is the most prevalent and lethal of the malaria parasites infecting humans, yet the origin and evolutionary history of this important pathogen remain controversial. Here we develop a single-genome amplification strategy to identify and characterize Plasmodium spp. DNA sequences in faecal samples from wild-living apes. Among nearly 3,000 specimens collected from field sites throughout central Africa, we found Plasmodium infection in chimpanzees (Pan troglodytes) and western gorillas (Gorilla gorilla), but not in eastern gorillas (Gorilla beringei) or bonobos (Pan paniscus). Ape plasmodial infections were highly prevalent, widely distributed and almost always made up of mixed parasite species. Analysis of more than 1,100 mitochondrial, apicoplast and nuclear gene sequences from chimpanzees and gorillas revealed that 99% grouped within one of six host-specific lineages representing distinct Plasmodium species within the subgenus Laverania. One of these from western gorillas comprised parasites that were nearly identical to P. falciparum. In phylogenetic analyses of full-length mitochondrial sequences, human P. falciparum formed a monophyletic lineage within the gorilla parasite radiation. These findings indicate that P. falciparum is of gorilla origin and not of chimpanzee, bonobo or ancient human origin.

The quest for universal access to effective malaria treatment: how can the AMFm contribute?

Access to quality assured artemisinin-based combination therapy (ACT) has remained very low in most malaria endemic countries. A number of reasons, including unaffordable prices, have contributed to the low accessibility to these life-saving medicines. The Affordable Medicines Facility-Malaria (AMFm) is a mechanism to increase access to quality assured ACT. The AMFm will use price signals and a combination of public and private sector channels to achieve multiple public health objectives: replacing older and increasingly ineffective anti-malarial medicines, such as chloroquine and sulphadoxine-pyrimethamine with ACT, displacing oral artemisinin monotherapies from the market, and prolonging the lifespan of ACT by reducing the likelihood of resistance to artemisinin.

Access to medicines frameworks paint a broad picture of dimensions of access to medicines and juxtapose components that enhance or hinder access to medicines. Access requires various activities--funding, institutions, interventions, and thinking--from public and private actors at global, national, and local levels. This paper examines, within access to medicines frameworks, the role of the AMFm across and within each dimension and discusses how the AMFm can help to solve access bottlenecks.

Breastfeeding and the risk of malaria in children born to HIV-infected and uninfected mothers in rural Uganda

BACKGROUND

Early cessation of breastfeeding increases morbidity and mortality of children born to HIV-infected mothers in resource-limited settings. However, data on whether breastfeeding reduces the risk of malaria in HIV-exposed and HIV-infected children is limited.

METHODS

We prospectively followed 99 HIV-unexposed children, 202 HIV-exposed children, and 45 HIV-infected children in a high malaria transmission area in Uganda. All children were given insecticide-treated bednets. HIV-exposed and HIV-infected children were given trimethoprim-sulfamethoxazole prophylaxis. Malaria diagnosis was based on fever and a positive blood smear. Date of breastfeeding cessation was determined through monthly questionnaires. Associations between breastfeeding and the risk of malaria were modeled through binomial generalized estimating equations using multivariate analysis adjusting for repeated measures, age, and location of residence. Analyses were stratified according to mothers' and children's HIV status.

RESULTS

Breastfeeding was associated with a significantly lower risk of malaria in 6-15 months old HIV-exposed children (relative risk [RR] = 0.62; P = 0.008) and 6-15 months old HIV-infected children (RR = 0.31; P = 0.002). However, breastfeeding was not protective against malaria for >15-24 months old HIV-unexposed (RR = 1.14; P = 0.21) or >15-24 months old HIV-infected children (RR = 1.11; P = 0.75).

CONCLUSIONS

HIV-infected mothers should be counseled about the importance of breastfeeding and trimethoprim-sulfamethoxazole prophylaxis to protect their young children and themselves against malaria.

A model of host response to a multi-stage pathogen

We model the immune surveillance of a pathogen which passes through n immunologically distinct stages. The biological parameters of this system induce a partial order on the stages, and this, in turn, determines which stages will be subject to immune regulation. This corresponds to the system's unique asymptotically stable fixed point.

Possession and usage of insecticidal bed nets among the people of Uganda: is BRAC Uganda Health Programme pursuing a pro-poor path?

Background

The use of insecticidal bed nets is found to be an effective public health tool for control of malaria, especially for under-five children and pregnant women. BRAC, an indigenous Bangladeshi non-governmental development organization, started working in the East African state of Uganda in June 2006. As part of its efforts to improve the health and well-being of its participants, BRAC Uganda has been distributing long lasting insecticide-treated bed nets (LLIN) at a subsidized price through health volunteers since February 2008. This study was conducted in March-April 2009 to examine how equitable the programme had been in consistence with BRAC Uganda's pro-poor policy.

Methodology/Principal Findings

Information on possession of LLINs and relevant knowledge on its proper use and maintenance was collected from households either with an under-five child and/or a pregnant woman. The sample included three villages from each of the 10 branch offices where BRAC Uganda's community-based health programme was operating. Data were collected by trained enumerators through face-to-face interviews using a hand-held personal digital assistant (PDA). Findings reveal that the study population had superficial knowledge on malaria and its transmission, including the use and maintenance of LLINs. The households' rate of possession of bed nets (41–59%), and the proportion of under-five children (17–19%) and pregnant women (25–27%) who reported sleeping under an LLIN were not encouraging. Inequity was observed in the number of LLINs possessed by the households, in the knowledge on its use and maintenance, and between the two programme areas.

Conclusions/Significance

The BRAC Uganda's LLINs distribution at a subsidized price appeared to be inadequate and inequitable, and BRAC's knowledge dissemination is insufficient for initiating preventive actions such as proper use of LLINs to interrupt malaria transmission. Findings contribute to the on-going debate on LLINs distribution in Africa and make a strong case for its free distribution.

Development of temporal modelling for forecasting and prediction of malaria infections using time-series and ARIMAX analyses: a case study in endemic districts of Bhutan

Background

Malaria still remains a public health problem in some districts of Bhutan despite marked reduction of cases in last few years. To strengthen the country's prevention and control measures, this study was carried out to develop forecasting and prediction models of malaria incidence in the endemic districts of Bhutan using time series and ARIMAX.

Methods

This study was carried out retrospectively using the monthly reported malaria cases from the health centres to Vector-borne Disease Control Programme (VDCP) and the meteorological data from Meteorological Unit, Department of Energy, Ministry of Economic Affairs. Time series analysis was performed on monthly malaria cases, from 1994 to 2008, in seven malaria endemic districts. The time series models derived from a multiplicative seasonal autoregressive integrated moving average (ARIMA) was deployed to identify the best model using data from 1994 to 2006. The best-fit model was selected for each individual district and for the overall endemic area was developed and the monthly cases from January to December 2009 and 2010 were forecasted. In developing the prediction model, the monthly reported malaria cases and the meteorological factors from 1996 to 2008 of the seven districts were analysed. The method of ARIMAX modelling was employed to determine predictors of malaria of the subsequent month.

Results

It was found that the ARIMA (p, d, q) (P, D, Q)^s model (p and P representing the auto regressive and seasonal autoregressive; d and D representing the non-seasonal differences and seasonal differencing; and q and Q the moving average parameters and seasonal moving average parameters, respectively and s representing the length of the seasonal period) for the overall endemic districts was (2,1,1)(0,1,1)¹²; the modelling data from each district revealed two most common ARIMA models including (2,1,1)(0,1,1)¹² and (1,1,1)(0,1,1)¹². The forecasted monthly malaria cases from January to December 2009 and 2010 varied from 15 to 82 cases in 2009 and 67 to 149 cases in 2010, where population in 2009 was 285,375 and the expected population of 2010 to be 289,085. The ARIMAX model of monthly cases and climatic factors showed considerable variations among the different districts. In general, the mean maximum temperature lagged at one month was a strong positive predictor of an increased malaria cases for four districts. The monthly number of cases of the previous month was also a significant predictor in one district, whereas no variable could predict malaria cases for two districts.

Conclusions

The ARIMA models of time-series analysis were useful in forecasting the number of cases in the endemic areas of Bhutan. There was no consistency in the predictors of malaria cases when using ARIMAX model with selected lag times and climatic predictors. The ARIMA forecasting models could be employed for planning and managing malaria prevention and control programme in Bhutan.

Incidence of malaria and efficacy of combination antimalarial therapies over 4 years in an urban cohort of Ugandan children

Background

Combination therapies are now recommended to treat uncomplicated malaria. We used a longitudinal design to assess the incidence of malaria and compare the efficacies of 3 combination regimens in Kampala, Uganda.

Methodology/Principal Findings

Children aged 1–10 years were enrolled from randomly selected households in 2004–05 and 2007, and were followed at least monthly through 2008. Insecticide-treated bednets (ITNs) were provided in 2006. Children were randomized upon their first episode, and then treated for all episodes of uncomplicated malaria with amodiaquine/sulfadoxine-pyrimethamine (AQ/SP), artesunate/amodiaquine (AS/AQ), or artemether/lumefantrine (AL). Risks of parasitological failure were determined for each episode of uncomplicated malaria and clinical parameters were followed.

A total of 690 children experienced 1464 episodes of malaria. 96% of these episodes were uncomplicated malaria and treated with study drugs; 94% were due to Plasmodium falciparum. The rank order of treatment efficacy was AL > AS/AQ > AQ/SP. Failure rates increased over time for AQ/SP, but not the artemisinin-based regimens. Over the 4-year course of the study the prevalence of asymptomatic parasitemia decreased from 11.8% to 1.4%, the incidence of malaria decreased from 1.55 to 0.32 per person year, and the prevalence of anemia (hemoglobin <10 gm/dL) decreased from 5.9% to 1.0%. No episodes of severe malaria (based on WHO criteria) and no deaths were seen.

Conclusions/Significance

With ready access to combination therapies and distribution of ITNs, responses were excellent for artemisinin-containing regimens, severe malaria was not seen, and the incidence of malaria and prevalence of parasitemia and anemia decreased steadily over time.

Trial Registration

isrctn.org ISRCTN37517549

Community perceptions of malaria and malaria treatment behaviour in a rural district of Ghana: implications for artemisinin combination therapy

BACKGROUND

Artesunate-amodiaquine (AS-AQ) was introduced in Ghana as the first line drug for treatment of uncomplicated malaria in 2004. We report the perceptions of malaria and malaria treatment behaviour, the community awareness of and perceptions about AS-AQ two years after the introduction of this ACT treatment for malaria.

METHODS

Two surveys were conducted; a cross-sectional survey of 729 randomly selected household heads (urban-362, rural-367) and 282 women with children < 5 years (urban-121, rural-161) was conducted in 2006. A district wide survey was conducted in 2007 to assess awareness of AS-AQ. These were complemented with twenty-eight focus group discussions (FGDs) and 16 key informant interviews (KII) among community members and major stakeholders in the health care delivery services. All nine (9) health facilities and five (5) purposively selected drug stores were audited in order to identify commonly used anti-malarials in the study area at the time of the survey.

RESULTS

Majority of respondents ( > 75%) in the sampled survey mentioned mosquito bites as the cause of malaria. Other causes mentioned include environmental factors (e.g. dirty surroundings) and standing in the sun. Close to 60% of the household heads and 40% of the care-givers interviewed did not know about AS-AQ. The community respondents who knew about and had ever taken AS-AQ perceived it to be a good drug; although they mentioned they had experienced some side effects including headaches and body weakness. Co-blistered AS-AQ was available in all the government health facilities in the study area. Different formulations of ACTs were however found in urban chemical shops but not in rural chemical stores where monotherapy antimalarials were predominant.

CONCLUSION

The knowledge of fever as a symptom of malaria is high among the study population. The awareness of AS-AQ therapy and its side-effect was low in the study area. Community education and sensitization, targeting all categories of the population, has to be intensified to ensure an efficient implementation process.

Plasmodium falciparum PfA-M1 aminopeptidase is trafficked via the parasitophorous vacuole and marginally delivered to the food vacuole

Background

The Plasmodium falciparum PfA-M1 aminopeptidase, encoded by a single copy gene, displays a neutral optimal activity at pH 7.4. It is thought to be involved in haemoglobin degradation and/or invasion of the host cells. Although a series of inhibitors developed against PfA-M1 suggest that this enzyme is a promising target for therapeutic intervention, the biological function(s) of the three different forms of the enzyme (p120, p96 and p68) are not fully understood. Two recent studies using PfA-M1 transfections have also provided conflicting results on PfA-M1 localization within or outside the food vacuole. Alternative destinations, such as the nucleus, have also been proposed.

Methods

By using a combination of techniques, such as cellular and biochemical fractionations, biochemical analysis, mass-spectrometry, immunofluorescence assays and live imaging of GFP fusions to various PfA-M1 domains, evidence is provided for differential localization and behaviour of the three different forms of PfA-M1 in the infected red blood cell which had not been established before.

Results

The high molecular weight p120 form of PfA-M1, the only version of the protein with a hydrophobic transmembrane domain, is detected both inside the parasite and in the parasitophorous vacuole while the processed p68 form is strictly soluble and localized within the parasite. The transient intermediate and soluble p96 form is localized at the border of parasitophorous vacuole and within the parasite in a compartment sensitive to high concentrations of saponin. Upon treatment with brefeldin A, the PfA-M1 maturation is blocked and the enzyme remains in a compartment close to the nucleus.

Conclusions

The PfA-M1 trafficking/maturation scenario that emerges from this data indicates that PfA-M1, synthesized as the precursor p120 form, is targeted to the parasitophorous vacuole via the parasite endoplasmic reticulum/Golgi, where it is converted into the transient p96 form. This p96 form is eventually redirected into the parasite to be converted into the processed p68 form that is only marginally delivered to the parasite food vacuole. These results provide insights on PfA-M1 topology regarding key compartments of the infected red blood cells that have important implications for the development of inhibitors targeting this plasmodial enzyme.

Tolerability and efficacy of a pediatric granule formulation of artesunate-mefloquine in young children from Cameroon with uncomplicated falciparum malaria

A fixed-dose pediatric formulation of artesunate and mefloquine (Artequin Pediatric) has been developed. In this open, non-comparative study in Cameroonian children with uncomplicated falciparum malaria, the safety and efficacy of this formulation was tested, with a particular emphasis on the risk of neuropsychiatric adverse events (AEs). In total, 220 subjects, weighing between 10 and 20 kg, were enrolled; 213 qualified for analysis. Artesunate-mefloquine was given once daily for 3 days. Overall, 13.1% of patients reported mild to moderate neuropsychiatric AEs (elicited through a structured questionnaire or reported spontaneously) out of which 3.8% (mainly insomnia) were considered drug-related. Other drug-related AEs were infrequent (< 3%). Polymerase chain reaction-corrected cure rate (adequate clinical and parasitological response) determined by survival analysis at 28 and 63 days was 96.6%. New infections were observed in 11.2% of evaluable patients at 63 days. The new formulation was well tolerated and efficacious in the population investigated.

In vitro and in vivo anti-malarial activity of Boerhavia elegans and Solanum surattense

BACKGROUND

There is an urgent need to identify new anti-malarial drug targets for both prophylaxis and chemotherapy, due to the increasing problem of drug resistance to malaria parasites. In the present study, the aim was to discover novel, effective plant-based extracts for the activity against malaria.

METHODS

Ten plants found in Iran were selected by ethnobotanical survey of medicinal plants. The crude ethanolic extracts were tested for in vitro anti-plasmodial activity against two strains of Plasmodium falciparum: K1 (chloroquine-resistant strain) and CY27 (chloroquine-sensitive strain), using the parasite lactate dehydrogenase (pLDH) assay. The anti-plasmodial activity of the extracts was also assessed in the 4-day suppressive anti-malarial assay in mice inoculated with Plasmodium berghei (ANKA strain). Crude ethanolic extracts showed good anti-plasmodial activity were further fractionated by partitioning in water and dichloromethane.

RESULTS

Of 10 plant species assayed, three species: Boerhavia elegans (Choisy), Solanum surattense (Burm.f.) and Prosopis juliflora (Sw.) showed promising anti-plasmodial activity in vitro (IC50 < or = 50 microg/ml) and in vivo with no toxicity. The dichloromethane fraction of three extracts revealed stronger anti-plasmodial activity than the total extracts.

CONCLUSION

Anti-plasmodial activities of extracts of B. elegans and S. surattense are reported for the first time.

Descriptive study on the efficacy of artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in Sudan

PURPOSE

The aim of this study was to investigate the efficacy of artemether-lumefantrine in treating uncomplicated Plasmodium falciparum malaria in four sentinel areas in Sudan with different malaria transmission (Damazin, Sinnar, and Kosti in the north, and Juba in the south).

METHODS

World Health Organization protocol for assessing antimalarial drug efficacy in treating uncomplicated P. falciparum malaria was employed. A total of 2,139 patients were screened, and 771 had P. falciparum monoinfection. Only 291 met the enrollment criteria and gave written consent to be recruited in the study. Patients were treated with artemether-lumefantrine tablets in a six-dose regimen calculated according to body weight. Tablets were given at 0, 8, 24, 36, 48, and 60 h. Patients were followed up for 28 days.

RESULTS

A total of 291 patients were recruited to the study, of whom ten [3.4; 95% confidence interval (CI):1.8-6.4%] patients showed early treatment failure (ETF) or late clinical failure (LCF) and were excluded from further follow-up. Of the remaining 281 patients, 276 (98.2%; 95% CI: 95.7-99.3%) completed the 28-day follow-up. Of these, 274 (99.3%; 95% CI: 97.1-99.9%) had adequate clinical and parasitological response (ACPR), and two (0.7%; 95% CI: 0.13-2.9%) showed late parasitological failure (LPF) at days 21 and 28. The overall mean +/- standard deviation (SD) of parasitemia and fever clearance times were 36.4 (23.7) h and 34.6 (19.2) h, respectively. Mild and reversible adverse effects were reported by 11 patients (3.8%; CI: 2.0- 7.0%) and were relieved without the need for termination of drug therapy or supportive treatment.

CONCLUSIONS

Our findings showed that artemether-lumefantrine was an effective and safe drug for treating uncomplicated P. falciparum malaria in northern and southern Sudan.

Transgenic Control of Vectors: The Effects of Interspecific Interactions

The control of insect vectors through conventional sterile insect or transgenic technologies (e.g., RIDL®) is an intense focus of research in the combat against vector-borne disease. While the population dynamic implications of these control strategies are reasonably well-established, the effects of interspecific competition between different vectors and control strategies have not previously been explored. Different control intervention methods can affect the interaction and potential coexistence of vector species. By altering the shape of the zero net growth isoclines, conventional and transgenic control can affect patterns of vector coexistence and/or exclusion through Allee effects and transient dynamics. Further, transgenic control methods can mediate coexistence between target and non-target species and this can have important consequences for the persistence of disease and community ecological interactions.

Anti-malarial market and policy surveys in sub-Saharan Africa

At a recent meeting (Sept 18, 2009) in which reasons for the limited access to artemisinin-based combination therapy (ACT) in sub-Saharan Africa were discussed, policy and market surveys on anti-malarial drug availability and accessibility in Burundi and Sierra Leone were presented in a highly interactive brainstorming session among key stakeholders across private, public, and not-for-profit sectors. The surveys, the conduct of which directly involved the national malaria control programme managers of the two countries, provides the groundwork for evidence-based policy implementation. The results of the surveys could be extrapolated to other countries with similar socio-demographic and malaria profiles. The meeting resulted in recommendations on key actions to be taken at the global, national, and community level for better ACT accessibility. At the global level, both public and private sectors have actions to take to strengthen policies that lead to the replacement of loose blister packs with fixed-dose ACT products, develop strategies to ban inappropriate anti-malarials and regulate those bans, and facilitate technology and knowledge transfer to scale up production of fixed-dose ACT products, which should be readily available and affordable to those patients who are in the greatest need of these medicines. At the national level, policies that regulate the anti-malarial medicines market should be enacted and enforced. The public sector, including funding donors, should participate in ensuring that the private sector is engaged in the ACT implementation process. Research similar to the surveys discussed is important for other countries to develop and evaluate the right incentives at a local level. At the community level, community outreach and education about appropriate preventive and treatment measures must continue and be strengthened, with service delivery systems developed within both public and private sectors, among other measures, to decrease access to ineffective and inappropriate anti-malarial medicines. What was clear during the meeting is that continuing commitment, strengthened interaction and transparency among various stakeholders, with focus on communities, national governments, and evidence-based policy and action are the only way to sustainably address the control of malaria, a disease which continues to have a significant health and socio-economic impact worldwide, particularly in sub-Saharan Africa. Details on the methodology employed in carrying out the studies discussed at this meeting, as well as more detailed results, data analysis and discussion of the studies are soon to be published.

Anti-malarial market and policy surveys in sub-Saharan Africa

At a recent meeting (Sept 18, 2009) in which reasons for the limited access to artemisinin-based combination therapy (ACT) in sub-Saharan Africa were discussed, policy and market surveys on anti-malarial drug availability and accessibility in Burundi and Sierra Leone were presented in a highly interactive brainstorming session among key stakeholders across private, public, and not-for-profit sectors. The surveys, the conduct of which directly involved the national malaria control programme managers of the two countries, provides the groundwork for evidence-based policy implementation. The results of the surveys could be extrapolated to other countries with similar socio-demographic and malaria profiles. The meeting resulted in recommendations on key actions to be taken at the global, national, and community level for better ACT accessibility. At the global level, both public and private sectors have actions to take to strengthen policies that lead to the replacement of loose blister packs with fixed-dose ACT products, develop strategies to ban inappropriate anti-malarials and regulate those bans, and facilitate technology and knowledge transfer to scale up production of fixed-dose ACT products, which should be readily available and affordable to those patients who are in the greatest need of these medicines. At the national level, policies that regulate the anti-malarial medicines market should be enacted and enforced. The public sector, including funding donors, should participate in ensuring that the private sector is engaged in the ACT implementation process. Research similar to the surveys discussed is important for other countries to develop and evaluate the right incentives at a local level. At the community level, community outreach and education about appropriate preventive and treatment measures must continue and be strengthened, with service delivery systems developed within both public and private sectors, among other measures, to decrease access to ineffective and inappropriate anti-malarial medicines. What was clear during the meeting is that continuing commitment, strengthened interaction and transparency among various stakeholders, with focus on communities, national governments, and evidence-based policy and action are the only way to sustainably address the control of malaria, a disease which continues to have a significant health and socio-economic impact worldwide, particularly in sub-Saharan Africa. Details on the methodology employed in carrying out the studies discussed at this meeting, as well as more detailed results, data analysis and discussion of the studies are soon to be published.

The bisnaphthalimides as new active lead compounds against Plasmodium falciparum

The bisquaternary bisnaphthalimides are a versatile class of compounds being active against the malaria parasite Plasmodium falciparum in the lower nanomolar range of concentration combined with no cytotoxicity. The series of compounds is designed as choline analogues and interfering agents of the phosphatidylcholine biosynthesis. The qualitative analysis of the structure-activity relationships (SAR) revealed the importance of a long methylene middle chain of at least 8 methylene groups between the two bisquaternary naphthalimides or a monoquaternary naphthalimide consisting of a long alkyl chain attached to the positively charged nitrogen atom. Since the SARs are different from reported biscationic antimalarial drugs the mode of action remains to be elucidated.

Selection of known Plasmodium falciparum resistance-mediating polymorphisms by artemether-lumefantrine and amodiaquine-sulfadoxine-pyrimethamine but not dihydroartemisinin-piperaquine in Burkina Faso

Artemether-lumefantrine (AL), dihydroartemisinin-piperaquine (DP), and amodiaquine-sulfadoxine-pyrimethamine (AQ-SP) offer excellent antimalarial efficacy but may select for parasite polymorphisms that decrease drug sensitivity. We evaluated the selection of known polymorphisms in genes encoding putative transporters (pfcrt and pfmdr1) and SP targets (pfdhfr and pfdhps) in parasites that caused new infections within 42 days of therapy for uncomplicated falciparum malaria in Burkina Faso. In 559 children in 2006, 42-day genotype-uncorrected failures were seen in 31.2% with AL, 11.8% with AQ-SP, and 7.6% with DP. After prior AL therapy, selection of wild-type sequences was seen for K76T in pfcrt (72.7% mixed or mutant results pretreatment versus 52.1% in new infections; P = 0.008) and N86Y (36.0% versus 18.7%; P = 0.025) and Y184F (66.7% versus 45.8%; P = 0.009) in pfmdr1. After prior AQ-SP therapy, selection of mutant sequences was seen for N51I (30.8% versus 61.5%; P = 0.05), C59R (28.2% versus 76.9%; P = 0.002), and S108N (30.8% versus 76.9%; P = 0.005) in pfdhfr. After prior DP therapy, selection was not seen for K76T (72.7% versus 77.8%; P = 0.96) in pfcrt or N86Y (36.0% versus 33.3%; P = 0.84), Y184F (66.7% versus 77.8%; P = 0.39), or D1246Y (9.3% versus 0%; P = 0.42) in pfmdr1. In 378 additional treatments with DP in 2007, 42-day uncorrected failure was seen in 10.9%. After prior DP, selection was again not seen for K76T (66.7% mixed or mutant results versus 59.5%; P = 0.43) in pfcrt or N86Y (38.7% versus 40.5%; P = 0.85), Y184F (67.6% versus 73.0%; P = 0.54), or D1246Y (3.6% versus 8.1%; P = 0.50) in pfmdr1. Despite its chemical similarity, piperaquine did not select for the same polymorphisms as chloroquine or AQ, suggesting different mechanisms of resistance.

Beer consumption increases human attractiveness to malaria mosquitoes

Background

Malaria and alcohol consumption both represent major public health problems. Alcohol consumption is rising in developing countries and, as efforts to manage malaria are expanded, understanding the links between malaria and alcohol consumption becomes crucial. Our aim was to ascertain the effect of beer consumption on human attractiveness to malaria mosquitoes in semi field conditions in Burkina Faso.

Methodology/Principal Findings

We used a Y tube-olfactometer designed to take advantage of the whole body odour (breath and skin emanations) as a stimulus to gauge human attractiveness to Anopheles gambiae (the primary African malaria vector) before and after volunteers consumed either beer (n = 25 volunteers and a total of 2500 mosquitoes tested) or water (n = 18 volunteers and a total of 1800 mosquitoes). Water consumption had no effect on human attractiveness to An. gambiae mosquitoes, but beer consumption increased volunteer attractiveness. Body odours of volunteers who consumed beer increased mosquito activation (proportion of mosquitoes engaging in take-off and up-wind flight) and orientation (proportion of mosquitoes flying towards volunteers' odours). The level of exhaled carbon dioxide and body temperature had no effect on human attractiveness to mosquitoes. Despite individual volunteer variation, beer consumption consistently increased attractiveness to mosquitoes.

Conclusions/Significance

These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures.

Reversal agent and linker variants of reversed chloroquines: activities against Plasmodium falciparum

We have shown that "reversed chloroquine molecules" constructed from chloroquine-like and resistance "reversal-agent"-like cores can be powerful drugs against malaria ( J. Med. Chem. 2006 , 49 , 5623 - 5625 ). Several reversed chloroquines are now presented that probe parameters governing the activities against chloroquine-resistant and chloroquine-sensitive malaria strains. The design is tolerant to linker and reversal agent changes, but a piperazinyl group adjacent to the quinoline, at least for the group of compounds studied here, may be detrimental.

German flooding of the Pontine Marshes in World War II

The German army's 1943 flooding of the Pontine Marshes south of Rome, which later caused a sharp rise in malaria cases among Italian civilians, has recently been described by historian Frank Snowden as a unique instance of biological warfare and bioterrorism in the European theater of war and, consequently, as a violation of the 1925 Geneva Protocol prohibiting chemical and biological warfare. We argue that archival documents fail to support this allegation, on several counts. As a matter of historical record, Hitler prohibited German biological weapons (BW) development and consistently adhered to the Geneva Protocol. Rather than biological warfare against civilians, the Wehrmacht used flooding, land mines, and the destruction of vital infrastructure to obstruct the Allied advance. To protect its own troops in the area, the German army sought to contain the increased mosquito breeding likely to be caused by the flooding. Italians returning to the Pontine Marshes after the German retreat in 1944 suffered malaria as a result of environmental destruction, which was banned by the 1899 and 1907 Hague Conventions and by subsequent treaties. In contrast, a state's violation of the Geneva Protocol, whether past or present, involves the use of germ weapons and, by inference, a state-level capability. Any allegation of such a serious violation demands credible evidence that meets high scientific and legal standards of proof.

Stability and potency of the Plasmodium falciparum MSP1-19/AMA-1(III) chimeric vaccine candidate with Montanide ISA720 adjuvant

The Plasmodium falciparum AMA-1(III) and MSP1-19 proteins have been expressed as a chimera (PfCP-2.9), adjuvanted with Montanide ISA720 and developed as a vaccine candidate tested in human. The PfCP-2.9 protein contains 18 cysteine residues that form nine intramolecular disulfide bonds. The protective immune responses induced by the chimeric protein were dependent on its disulfide bond-based conformation. In this study, we developed a sandwich ELISA to assess the nature of the protein in the emulsion over time (6, 12 and 18 months). Our results showed that the OD(450) values corresponding to vaccine storages were within the 95% confidence interval, indicating that the conformation of the protein in the emulsion stored for up to 18 months at 4 degrees C was unchanged. Furthermore, no protein degradation was detected by Coomassie blue, silver staining, and Western blot analysis for samples stored at 4 degrees C for up to 2 years. Although some protein aggregation was observed in the emulsion preparations, these aggregates were only a small percentage of the total protein in the sample (7.6%). Moreover, the protein multimers maintained their conformational epitope. The potency assay of the formulation showed no significant differences in ED(50) values (50% effective dose for achieving seroconversion) between fresh vaccine formulations (ED(50)=0.057+/-0.024 microg) and formulations stored for up to 6 (ED(50)=0.046 microg) or 12 months (ED(50)=0.040 microg). Importantly, the immune sera of rabbits immunized with formulations stored for 0, 3, 6, 9 and 12 months effectively inhibited parasite growth in vitro at similar levels. These data indicated that the vaccine emulsion was stable over long periods of storage and maintained both its physical and biological properties.

Using the social entrepreneurship approach to generate innovative and sustainable malaria diagnosis interventions in Tanzania: a case study

BACKGROUND

There have been a number of interventions to date aimed at improving malaria diagnostic accuracy in sub-Saharan Africa. Yet, limited success is often reported for a number of reasons, especially in rural settings. This paper seeks to provide a framework for applied research aimed to improve malaria diagnosis using a combination of the established methods, participatory action research and social entrepreneurship.

METHODS

This case study introduces the idea of using the social entrepreneurship approach (SEA) to create innovative and sustainable applied health research outcomes. The following key elements define the SEA: (1) identifying a locally relevant research topic and plan, (2) recognizing the importance of international multi-disciplinary teams and the incorporation of local knowledge, (3) engaging in a process of continuous innovation, adaptation and learning, (4) remaining motivated and determined to achieve sustainable long-term research outcomes and, (5) sharing and transferring ownership of the project with the international and local partner.

EVALUATION

The SEA approach has a strong emphasis on innovation lead by local stakeholders. In this case, innovation resulted in a unique holistic research program aimed at understanding patient, laboratory and physician influences on accurate diagnosis of malaria. An evaluation of milestones for each SEA element revealed that the success of one element is intricately related to the success of other elements.

CONCLUSIONS

The SEA will provide an additional framework for researchers and local stakeholders that promotes innovation and adaptability. This approach will facilitate the development of new ideas, strategies and approaches to understand how health issues, such as malaria, affect vulnerable communities.

Chloroplast-derived vaccine antigens confer dual immunity against cholera and malaria by oral or injectable delivery

Cholera and malaria are major diseases causing high mortality. The only licensed cholera vaccine is expensive; immunity is lost in children within 3 years and adults are not fully protected. No vaccine is yet available for malaria. Therefore, in this study, the cholera toxin-B subunit (CTB) of Vibrio cholerae fused to malarial vaccine antigens apical membrane antigen-1 (AMA1) and merozoite surface protein-1 (MSP1) was expressed in lettuce and tobacco chloroplasts. Southern blot analysis confirmed homoplasmy and stable integration of transgenes. CTB-AMA1 and CTB-MSP1 fusion proteins accumulated up to 13.17% and 10.11% (total soluble protein, TSP) in tobacco and up to 7.3% and 6.1% (TSP) in lettuce, respectively. Nine groups of mice (n = 10/group) were immunized subcutaneously (SQV) or orally (ORV) with purified antigens or transplastomic tobacco leaves. Significant levels of antigen-specific antibody titres of immunized mice completely inhibited proliferation of the malarial parasite and cross-reacted with the native parasite proteins in immunoblots and immunofluorescence studies. Protection against cholera toxin challenge in both ORV (100%) and SQV (89%) mice correlated with CTB-specific titres of intestinal, serum IgA and IgG1 in ORV and only IgG1 in SQV mice, but no other immunoglobulin. Increasing numbers of interleukin-10(+) T cell but not Foxp3(+) regulatory T cells, suppression of interferon-gamma and absence of interleukin-17 were observed in protected mice, suggesting that immunity is conferred via the Tr1/Th2 immune response. Dual immunity against two major infectious diseases provided by chloroplast-derived vaccine antigens for long-term (>300 days, 50% of mouse life span) offers a realistic platform for low cost vaccines and insight into mucosal and systemic immunity.

Infection of the malaria mosquito, Anopheles gambiae, with two species of entomopathogenic fungi: effects of concentration, co-formulation, exposure time and persistence

Background

Entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana isolates have been shown to infect and reduce the survival of mosquito vectors.

Methods

Here four different bioassays were conducted to study the effect of conidia concentration, co-formulation, exposure time and persistence of the isolates M. anisopliae ICIPE-30 and B. bassiana I93-925 on infection and survival rates of female Anopheles gambiae sensu stricto. Test concentrations and exposure times ranged between 1 × 10⁷ - 4 × 10¹⁰ conidia m^-2 and 15 min - 6 h. In co-formulations, 2 × 10¹⁰ conidia m^-2 of both fungus isolates were mixed at ratios of 4:1, 2:1, 1:1,1:0, 0:1, 1:2 and 1:4. To determine persistence, mosquitoes were exposed to surfaces treated 1, 14 or 28 d previously, with conidia concentrations of 2 × 10⁹, 2 × 10¹⁰ or 4 × 10¹⁰.

Results

Mosquito survival varied with conidia concentration; 2 × 10¹⁰ conidia m^-2 was the concentration above which no further reductions in survival were detectable for both isolates of fungus. The survival of mosquitoes exposed to single and co-formulated treatments was similar and no synergistic or additive effects were observed. Mosquitoes were infected within 30 min and longer exposure times did not result in a more rapid killing effect. Fifteen min exposure still achieved considerable mortality rates (100% mortality by 14 d) of mosquitoes, but at lower speed than with 30 min exposure (100% mortality by 9 d). Conidia remained infective up to 28 d post-application but higher concentrations did not increase persistence.

Conclusion

Both fungus isolates are effective and persistent at low concentrations and short exposure times.

Minireview: Invasive fungal infection complicating acute Plasmodium falciparum malaria

Malaria is the most important parasitic infection in people, affecting 5-10% of the world's population with more than two million deaths a year. Whereas invasive bacterial infections are not uncommon during severe Plasmodium falciparum malaria, only a few cases of opportunistic fungal infections have been reported. Here, we present a fatal case of disseminated hyalohyphomycosis associated with acute P. falciparum malaria in a non-immune traveller, review the cases reported in the literature and discuss the theoretical foundations for the increased susceptibility of non-immune individuals with severe P. falciparum malaria to opportunistic fungal infections. Apart from the availability of free iron as sequelae of massive haemolysis, tissue damage, acidosis and measures of advanced life support, patients with complicated P. falciparum malaria also are profoundly immunosuppressed by the organism's interaction with innate and adaptive host immune mechanisms.

Estimating and testing haplotype-trait associations in non-diploid populations

Malaria is an infectious disease that is caused by a group of parasites of the genus Plasmodium. Characterizing the association between polymorphisms in the parasite genome and measured traits in an infected human host may provide insight into disease aetiology and ultimately inform new strategies for improved treatment and prevention. This, however, presents an analytic challenge since individuals are often multiply infected with a variable and unknown number of genetically diverse parasitic strains. In addition, data on the alignment of nucleotides on a single chromosome, which is commonly referred to as haplotypic phase, is not generally observed. An expectation–maximization algorithm for estimating and testing associations between haplotypes and quantitative traits has been described for diploid (human) populations. We extend this method to account for both the uncertainty in haplotypic phase and the variable and unknown number of infections in the malaria setting. Further extensions are described for the human immunodeficiency virus quasi-species setting. A simulation study is presented to characterize performance of the method. Application of this approach to data arising from a cross-sectional study of n=126 multiply infected children in Uganda reveals some interesting associations requiring further investigation.

Access to malaria treatment in young children of rural Burkina Faso

Background

Effective and timely treatment is an essential aspect of malaria control, but remains a challenge in many parts of sub-Saharan Africa. The objective of this study was to describe young children's access to malaria treatment in Nouna Health District, Burkina Faso.

Methods

In February/March 2006, a survey was conducted in a representative sample of 1,052 households.

Results

Overall 149/1052 (14%) households reported the current possession of anti-malarial medicine, which was significantly associated with urban area, literacy of household head, having young children, and high socio-economic status. Out of a total of 802 children under five years, at least one malaria episode was reported for 239 (30%) within the last month. Overall 95% of children received treatment, either modern (72%), traditional (18%) or mixed (5%). Most of the medicines were provided as home treatment by the caregiver and half of children received some type of modern treatment within 24 hours of the occurrence of first symptoms. Despite a recent policy change to artemisinin-based combination therapy, modern anti-malarials consisted mainly of chloroquine (93%). Modern drugs were obtained more often from a health facility in localities with a health facility compared to those without (60% vs. 25.6%, p < 0.001). In contrast, beside informal providers, volunteer community health workers (CHW) were the main source of modern medicine in localities without a health centre (28% vs. 3%, p < 0.001).

Conclusion

Access to modern health services providing quality controlled effective combination therapies against malaria needs to be strengthened in rural Africa, which should include a re-investigation of the role of CHW 30 years after Alma Ata.

Synergy between repellents and organophosphates on bed nets: efficacy and behavioural response of natural free-flying An. gambiae mosquitoes

BACKGROUND

Chemicals are used on bed nets in order to prevent infected bites and to kill aggressive malaria vectors. Because pyrethroid resistance has become widespread in the main malaria vectors, research for alternative active ingredients becomes urgent. Mixing a repellent and a non-pyrethroid insecticide seemed to be a promising tool as mixtures in the laboratory showed the same features as pyrethroids.

METHODOLOGY/PRINCIPAL FINDINGS

We present here the results of two trials run against free-flying Anopheles gambiae populations comparing the effects of two insect repellents (either DEET or KBR 3023, also known as icaridin) and an organophosphate insecticide at low-doses (pirimiphos-methyl, PM) used alone and in combination on bed nets. We showed that mixtures of PM and the repellents induced higher exophily, blood feeding inhibition and mortality among wild susceptible and resistant malaria vectors than compounds used alone. Nevertheless the synergistic interactions are only involved in the high mortality induced by the two mixtures.

CONCLUSION

These field trials argue in favour of the strategy of mixing repellent and organophosphate on bed nets to better control resistant malaria vectors.

Household food insecurity is associated with childhood malaria in rural Haiti

Haiti is the poorest country in the Western Hemisphere and is heavily affected by food insecurity and malaria. To find out if these 2 conditions are associated with each other, we studied a convenience sample of 153 women with children 1-5 y old in Camp Perrin, South Haiti. Household food insecurity was assessed with the 16-item Escala Latinoamericana y Caribeña de Seguridad Alimentaria (ELCSA) scale previously validated in the target communities. ELCSA's reference time period was the 3 mo preceding the survey and it was answered by the mother. Households were categorized as either food secure (2%; ELCSA score = 0), food insecure/very food insecure (42.7%; ELCSA score range: 1-10), or severely food insecure (57.3%; ELCSA score range: 11-16). A total of 34.0% of women reported that their children had malaria during the 2 mo preceding the survey. Multivariate analyses showed that severe food insecure was a risk factor for perceived clinical malaria (odds ratio: 5.97; 95% CI: 2.06-17.28). Additional risk factors for perceived clinical malaria were as follows: not receiving colostrum, poor child health (via maternal self-report), a child BMI <17 kg/m(2), and child vitamin A supplementation more than once since birth. Findings suggest that policies and programs that address food insecurity are also likely to reduce the risk of malaria in Haiti.

Malaria parasite development in the mosquito and infection of the mammalian host

Plasmodium sporozoites are the product of a complex developmental process in the mosquito vector and are destined to infect the mammalian liver. Attention has been drawn to the mosquito stages and pre-erythrocytic stages owing to recognition that these are bottlenecks in the parasite life cycle and that intervention at these stages can block transmission and prevent infection. Parasite progression in the Anopheles mosquito, sporozoite transmission to the mammalian host by mosquito bite, and subsequent infection of the liver are characterized by extensive migration of invasive stages, cell invasion, and developmental changes. Preparation for the liver phase in the mammalian host begins in the mosquito with an extensive reprogramming of the sporozoite to support efficient infection and survival. Here, we discuss what is known about the molecular and cellular basis of the developmental progression of parasites and their interactions with host tissues in the mosquito and during the early phase of mammalian infection.

Barriers to the effective treatment and prevention of malaria in Africa: A systematic review of qualitative studies

BACKGROUND

In Africa, an estimated 300-500 million cases of malaria occur each year resulting in approximately 1 million deaths. More than 90% of these are in children under 5 years of age. To identify commonly held beliefs about malaria that might present barriers to its successful treatment and prevention, we conducted a systematic review of qualitative studies examining beliefs and practices concerning malaria in sub-Saharan African countries.

METHODS

We searched Medline and Scopus (1966-2009) and identified 39 studies that employed qualitative methods (focus groups and interviews) to examine the knowledge, attitudes, and practices of people living in African countries where malaria is endemic. Data were extracted relating to study characteristics, and themes pertaining to barriers to malaria treatment and prevention.

RESULTS

The majority of studies were conducted in rural areas, and focused mostly or entirely on children. Major barriers to prevention reported included a lack of understanding of the cause and transmission of malaria (29/39), the belief that malaria cannot be prevented (7/39), and the use of ineffective prevention measures (12/39). Thirty-seven of 39 articles identified barriers to malaria treatment, including concerns about the safety and efficacy of conventional medicines (15/39), logistical obstacles, and reliance on traditional remedies. Specific barriers to the treatment of childhood malaria identified included the belief that a child with convulsions could die if given an injection or taken to hospital (10/39).

CONCLUSION

These findings suggest that large-scale malaria prevention and treatment programs must account for the social and cultural contexts in which they are deployed. Further quantitative research should be undertaken to more precisely measure the impact of the themes uncovered by this exploratory analysis.

Characterization of immunoglobulin G antibodies to Plasmodium falciparum sporozoite surface antigen MB2 in malaria exposed individuals

BACKGROUND

MB2 protein is a sporozoite surface antigen on the human malaria parasite Plasmodium falciparum. MB2 was identified by screening a P. falciparum sporozoite cDNA expression library using immune sera from a protected donor immunized via the bites of P. falciparum-infected irradiated mosquitoes. It is not known whether natural exposure to P. falciparum also induces the anti-MB2 response and if this response differs from that in protected individuals immunized via the bites of P. falciparum infected irradiated mosquitoes. The anti-MB2 antibody response may be part of a robust protective response against the sporozoite.

METHODS

Fragments of polypeptide regions of MB2 were constructed as recombinant fusions sandwiched between glutathione S-transferase and a hexa histidine tag for bacterial expression. The hexa histidine tag affinity purified proteins were used to immunize rabbits and the polyclonal sera evaluated in an in vitro inhibition of sporozoite invasion assay. The proteins were also used in immunoblots with sera from a limited number of donors immunized via the bites of P. falciparum infected irradiated mosquitoes and plasma and serum obtained from naturally exposed individuals in Kenya.

RESULTS

Rabbit polyclonal antibodies targeting the non-repeat region of the basic domain of MB2 inhibited sporozoites entry into HepG2-A16 cells in vitro. Analysis of serum from five human volunteers that were immunized via the bites of P. falciparum infected irradiated mosquitoes that developed immunity and were completely protected against subsequent challenge with non-irradiated parasite also had detectable levels of antibody against MB2 basic domain. In contrast, in three volunteers not protected, anti-MB2 antibodies were below the level of detection. Sera from protected volunteers preferentially recognized a non-repeat region of the basic domain of MB2, whereas plasma from naturally-infected individuals also had antibodies that recognize regions of MB2 that contain a repeat motif in immunoblots. Sequence analysis of eleven field isolates and four laboratory strains showed that these antigenic regions of the basic domain of the MB2 gene are highly conserved in parasites obtained from different parts of the world. Moreover, anti-MB2 antibodies also were detected in the plasma of 83% of the individuals living in a malaria endemic area of Kenya (n = 41).

CONCLUSION

A preliminary analysis of the human humoral response against MB2 indicates that it may be an additional highly conserved target for immune intervention at the pre-erythrocytic stage of P. falciparum life cycle.

Imported malaria in Korea: a 13-year experience in a single center

The incidence of imported malaria has been increasing in Korea. We reviewed data retrospectively to evaluate the epidemiology, clinical features, and outcomes of imported malaria from 1995 to 2007 in a university hospital. All patients diagnosed with imported malaria were included. Imported malaria was defined as a positive smear for malaria that was acquired in a foreign country. A total of 49 patients (mean age, 35.7 year; M : F = 38 : 11) were enrolled. The predominant malarial species was Plasmodium falciparum (73.5%), and the most frequent area of acquisition was Africa (55.1%), followed by Southeast Asia (22.4%) and South Asia (18.4%). Fourteen-patients (30.6%) suffered from severe malaria caused by P. falciparum and 1 patient (2.0%) died of multiorgan failure. Most of the patients were treated with mefloquine (79.2%) or quinine (10.2%); other antimalarial agents had to be given in 13.2% treated with mefloquine and 44.4% with quinine due to adverse drug events (ADEs). P. falciparum was the most common cause of imported malaria, with the majority of cases acquired from Africa, and a significant number of patients had severe malaria. Alternative antimalarial agents with lower rates of ADEs might be considered for effective treatment instead of mefloquine and quinine.

Malaria prevalence in endemic districts of Bangladesh

Background

Following the 1971 ban of DDT in Bangladesh, malaria cases have increased steadily. Malaria persists as a major health problem in the thirteen south-eastern and north-eastern districts of Bangladesh. At present the national malaria control program, largely supported by the Global Fund for AIDS, Tuberculosis and Malaria (GFATM), provides interventions including advocacy at community level, Insecticide Treated Net (ITN) distribution, introduction of Rapid Diagnostic Tests (RDT) and combination therapy with Coartem. It is imperative, therefore, that baseline data on malaria prevalence and other malaria indicators are collected to assess the effectiveness of the interventions and rationalize the prevention and control efforts. The objective of this study was to obtain this baseline on the prevalence of malaria and bed net use in the thirteen malaria endemic districts of Bangladesh.

Methods and Principal Findings

In 2007, BRAC and ICDDR,B carried out a malaria prevalence survey in thirteen malaria endemic districts of Bangladesh. A multi-stage cluster sampling technique was used and 9750 blood samples were collected. Rapid Diagnostic Tests (RDT) were used for the diagnosis of malaria. The weighted average malaria prevalence in the thirteen endemic districts was 3.97%. In five south-eastern districts weighted average malaria prevalence rate was 6.00% and in the eight north-eastern districts weighted average malaria prevalence rate was (0.40%). The highest malaria prevalence was observed in Khagrachari district. The majority of the cases (90.18%) were P. falciparum infections. Malaria morbidity rates in five south-eastern districts was 2.94%. In eight north-eastern districts, morbidity was 0.07%.

Conclusion and Significance

Bangladesh has hypoendemic malaria with P. falciparum the dominant parasite species. The malaria situation in the five north-eastern districts of Bangladesh in particular warrants urgent attention. Detailed maps of the baseline malaria prevalence and summaries of the data collected are provided along with the survey results in full, in a supplemental information

Plant-derived antimalarial agents: new leads and efficient phytomedicines. Part II. Non-alkaloidal natural products

Malaria is still the most destructive and dangerous parasitic infection in many tropical and subtropical countries. The burden of this disease is getting worse, mainly due to the increasing resistance of Plasmodium falciparum against the widely available antimalarial drugs. There is an urgent need for new, more affordable and accessible antimalarial agents possessing original modes of action. Natural products have played a dominant role in the discovery of leads for the development of drugs to treat human diseases, and this fact anticipates that new antimalarial leads may certainly emerge from tropical plant sources. This present review covers most of the recently-published non-alkaloidal natural compounds from plants with antiplasmodial and antimalarial properties, belonging to the classes of terpenes, limonoids, flavonoids, chromones, xanthones, anthraquinones, miscellaneous and related compounds, besides the majority of papers describing antiplasmodial crude extracts published in the last five years not reviewed before. In addition, some perspectives and remarks on the development of new drugs and phytomedicines for malaria are succinctly discussed.

Evaluation of RTS,S/AS02A and RTS,S/AS01B in adults in a high malaria transmission area

Background

This study advances the clinical development of the RTS,S/AS01B candidate malaria vaccine to malaria endemic populations. As a primary objective it compares the safety and reactogenicity of RTS,S/AS01B to the more extensively evaluated RTS,S/AS02A vaccine.

Methodology

A Phase IIb, single centre, double-blind, controlled trial of 6 months duration with a subsequent 6 month single-blind follow-up conducted in Kisumu West District, Kenya between August 2005 and August 2006. 255 healthy adults aged 18 to 35 years were randomized (1∶1∶1) to receive 3 doses of RTS,S/AS02A, RTS,S/AS01B or rabies vaccine (Rabipur®; Chiron Behring GmbH) at months 0, 1, 2. The primary objective was the occurrence of severe (grade 3) solicited or unsolicited general (i.e. systemic) adverse events (AEs) during 7 days follow up after each vaccination.

Principal Findings

Both candidate vaccines had a good safety profile and were well tolerated. One grade 3 systemic AE occurred within 7 days of vaccination (RTS,S/AS01B group). No unsolicited AEs or SAEs were related to vaccine. A marked increase in anti-CS antibody GMTs was observed post Dose 2 of both RTS,S/AS01B (31.6 EU/mL [95% CI: 23.9 to 41.6]) and RTS,S/AS02A (16.7 EU/mL [95% CI: 12.9 to 21.7]). A further increase was observed post Dose 3 in both the RTS,S/AS01B (41.4 EU/mL [95% CI: 31.7 to 54.2]) and RTS,S/AS02A (21.4 EU/mL [95% CI: 16.0 to 28.7]) groups. Anti-CS antibody GMTs were significantly greater with RTS,S/AS01B compared to RTS,S/AS02A at all time points post Dose 2 and Dose 3. Both candidate vaccines produced strong anti-HBs responses. Vaccine efficacy in the RTS,S/AS01B group was 29.5% (95% CI: −15.4 to 56.9, p = 0.164) and in the RTS,S/AS02A group 31.7% (95% CI: −11.6 to 58.2, p = 0.128).

Conclusions

Both candidate malaria vaccines were well tolerated over a 12 month surveillance period. A more favorable immunogenicity profile was observed with RTS,S/AS01B than with RTS,S/AS02A.

Trial Registration

Clinicaltrials.gov NCT00197054

Knowledge on the transmission, prevention and treatment of malaria among two endemic populations of Bangladesh and their health-seeking behaviour

Background

Data on sociological and behavioural aspects of malaria, which is essential for an evidence-based design of prevention and control programmes, is lacking in Bangladesh. This paper attempts to fill this knowledge gap by using data from a population-based prevalence survey conducted during July to November 2007, in 13 endemic districts of Bangladesh.

Methods

A two-stage cluster sampling technique was used to select study respondents randomly from 30 mauzas in each district for the socio-behavioural inquiry (n = 9,750). A pre-tested, semi-structured questionnaire was used to collect data in face-to-face interview by trained interviewers, after obtaining informed consent.

Results

The overall malaria prevalence rate in the 13 endemic districts was found to be 3.1% by the Rapid Diagnostic Test 'FalciVax' (P. falciparum 2.73%, P. vivax 0.16% and mixed infection 0.19%), with highest concentration in the three hill districts (11%). Findings revealed superficial knowledge on malaria transmission, prevention and treatment by the respondents. Poverty and level of schooling were found as important determinants of malaria knowledge and practices. Allopathic treatment was uniformly advocated, but the 'know-do' gap became especially evident when in practice majority of the ill persons either did not seek any treatment (31%) or practiced self-treatment (12%). Of those who sought treatment, the majority went to the village doctors and drugstore salespeople (around 40%). Also, there was a delay beyond twenty-four hours in beginning treatment of malaria-like fever in more than half of the instances. In the survey, gender divide in knowledge and health-seeking behaviour was observed disfavouring women. There was also a geographical divide between the high endemic south-eastern area and the low-endemicnorth-eastern area, the former being disadvantaged with respect to different aspects of malaria studied.

Conclusion

The respondents in this study lacked comprehensive knowledge on different aspects of malaria, which was influenced by level of poverty and education. A gender and geographical divide in knowledge was observed disfavouring women and south-eastern area respectively. They preferred allopathic treatment for malaria, although a substantial proportion did not seek any treatment or sought self-treatment for malaria-like fever. Delay in seeking care was common. The implications of these findings for programme development are discussed.