Long-Lasting Insecticide-Treated Nets Combined or Not with Indoor Residual Spraying May Not Be Sufficient to Eliminate Malaria: A Case-Control Study, Benin, West Africa.

In sub-Saharan Africa, despite the implementation of multiple control interventions, the prevalence of malaria infection and clinical cases remains high. The primary tool for vector control against malaria in this region is the use of long-lasting insecticide-treated nets (LLINs) combined or not with indoor residual spraying (IRS) to achieve a synergistic effect in protection. The objective of this study was to assess the effectiveness of LLINs, with or without IRS, protected against Plasmodium falciparum infection and uncomplicated clinical cases (UCC) of malaria in Benin. A case-control study was conducted, encompassing all age groups, in the urban area of Djougou and the rural area of Cobly. A cross-sectional survey was conducted that included 2080 individuals in the urban area and 2770 individuals in the rural area. In the urban area, sleeping under LLINs did not confer significant protection against malaria infection and UCC when compared to no intervention. However, certain neighbourhoods benefited from a notable reduction in infection rates ranging from 65% to 85%. In the rural area, the use of LLINs alone, IRS alone, or their combination did not provide additional protection compared to no intervention. IRS alone and LLINs combined with IRS provided 61% and 65% protection against malaria infection, respectively, compared to LLINs alone. The effectiveness of IRS alone and LLINs combined with IRS against UCC was 52% and 54%, respectively, when compared to LLINs alone. In both urban and rural areas, the use of LLINs alone, IRS alone, and their combination did not demonstrate significant individual protection against malaria infection and clinical cases when compared to no intervention. In the conditions of this study, LLINs combined or not with IRS are not effective enough to eliminate malaria. In addition to the interventions, this study identified factors associated with malaria in Benin as housing design, neglected social groups like gender-marginalised individuals and adolescents, and socio-economic conditions acting as barriers to effective malaria prevention. Addressing these factors is crucial in order to facilitate malaria elimination efforts in sub-Saharan Africa.

Bayesian spatial modelling of malaria burden in two contrasted eco-epidemiological facies in Benin (West Africa): call for localized interventions.

BACKGROUND: Despite a global decrease in malaria burden worldwide, malaria remains a major public health concern, especially in Benin children, the most vulnerable group. A better understanding of malaria's spatial and age-dependent characteristics can help provide durable disease control and elimination. This study aimed to analyze the spatial distribution of Plasmodium falciparum malaria infection and disease among children under five years of age in Benin, West Africa. METHODS: A cross-sectional epidemiological and clinical survey was conducted using parasitological examination and rapid diagnostic tests (RDT) in Benin. Interviews were done with 10,367 children from 72 villages across two health districts in Benin. The prevalence of infection and clinical cases was estimated according to age. A Bayesian spatial binomial model was used to estimate the prevalence of malaria infection, and clinical cases were adjusted for environmental and demographic covariates. It was implemented in R using Integrated Nested Laplace Approximations (INLA) and Stochastic Partial Differentiation Equations (SPDE) techniques. RESULTS: The prevalence of P. falciparum infection was moderate in the south (34.6%) of Benin and high in the northern region (77.5%). In the south, the prevalence of P. falciparum infection and clinical malaria cases were similar according to age. In northern Benin children under six months of age were less frequently infected than children aged 6-11, 12-23, 24-60 months, (p < 0.0001) and had the lowest risk of malaria cases compared to the other age groups (6-12), (13-23) and (24-60): OR = 3.66 [2.21-6.05], OR = 3.66 [2.21-6.04], and OR = 2.83 [1.77-4.54] respectively (p < 0.0001). Spatial model prediction showed more heterogeneity in the south than in the north but a higher risk of malaria infection and clinical cases in the north than in the south. CONCLUSION: Integrated and periodic risk mapping of Plasmodium falciparum infection and clinical cases will make interventions more evidence-based by showing progress or a lack in malaria control.

Single low-dose primaquine for blocking transmission of Plasmodium falciparum malaria - a proposed model-derived age-based regimen for sub-Saharan Africa.

BACKGROUND: In 2012, the World Health Organization recommended blocking the transmission of Plasmodium falciparum with single low-dose primaquine (SLDPQ, target dose 0.25 mg base/kg body weight), without testing for glucose-6-phosphate dehydrogenase deficiency (G6PDd), when treating patients with uncomplicated falciparum malaria. We sought to develop an age-based SLDPQ regimen that would be suitable for sub-Saharan Africa. METHODS: Using data on the anti-infectivity efficacy and tolerability of primaquine (PQ), the epidemiology of anaemia, and the risks of PQ-induced acute haemolytic anaemia (AHA) and clinically significant anaemia (CSA), we prospectively defined therapeutic-dose ranges of 0.15-0.4 mg PQ base/kg for children aged 1-5 years and 0.15-0.5 mg PQ base/kg for individuals aged ≥6 years (therapeutic indices 2.7 and 3.3, respectively). We chose 1.25 mg PQ base for infants aged 6-11 months because they have the highest rate of baseline anaemia and the highest risks of AHA and CSA. We modelled an anthropometric database of 661,979 African individuals aged ≥6 months (549,127 healthy individuals, 28,466 malaria patients and 84,386 individuals with other infections/illnesses) by the Box-Cox transformation power exponential and tested PQ doses of 1-15 mg base, selecting dosing groups based on calculated mg/kg PQ doses. RESULTS: From the Box-Cox transformation power exponential model, five age categories were selected: (i) 6-11 months (n = 39,886, 6.03%), (ii) 1-5 years (n = 261,036, 45.46%), (iii) 6-9 years (n = 20,770, 3.14%), (iv) 10-14 years (n = 12,155, 1.84%) and (v) ≥15 years (n = 328,132, 49.57%) to receive 1.25, 2.5, 5, 7.5 and 15 mg PQ base for corresponding median (1st and 99th centiles) mg/kg PQ base of: (i) 0.16 (0.12-0.25), (ii) 0.21 (0.13-0.37), (iii) 0.25 (0.16-0.38), (iv) 0.26 (0.15-0.38) and (v) 0.27 (0.17-0.40). The proportions of individuals predicted to receive optimal therapeutic PQ doses were: 73.2 (29,180/39,886), 93.7 (244,537/261,036), 99.6 (20,690/20,770), 99.4 (12,086/12,155) and 99.8% (327,620/328,132), respectively. CONCLUSIONS: We plan to test the safety of this age-based dosing regimen in a large randomised placebo-controlled trial (ISRCTN11594437) of uncomplicated falciparum malaria in G6PDd African children aged 0.5 - 11 years. If the regimen is safe and demonstrates adequate pharmacokinetics, it should be used to support malaria elimination.

Effectiveness of insecticidal nets on uncomplicated clinical malaria: a case-control study for operational evaluation.

BACKGROUND: In a context of large-scale implementation of malaria vector control tools, such as the distribution of long-lasting insecticide nets (LLIN), it is necessary to regularly assess whether strategies are progressing as expected and then evaluate their effectiveness. The present study used the case-control approach to evaluate the effectiveness of LLIN 42 months after national wide distribution. This study design offers an alternative to cohort study and randomized control trial as it permits to avoid many ethical issues inherent to them. METHODS: From April to August 2011, a case-control study was conducted in two health districts in Benin; Ouidah-Kpomasse-Tori (OKT) in the south and Djougou-Copargo-Ouake (DCO) in the north. Children aged 0-60 months randomly selected from community were included. Cases were children with a high axillary temperature (≥37.5 °C) or a reported history of fever during the last 48 h with a positive rapid diagnostic test (RDT). Controls were children with neither fever nor signs suggesting malaria with a negative RDT. The necessary sample size was at least 396 cases and 1188 controls from each site. The main exposure variable was "sleeping every night under an LLIN for the 2 weeks before the survey" (SL). The protective effectiveness (PE) of LLIN was calculated as PE = 1 - odds ratio. RESULTS: The declared SL range was low, with 17.0 and 27.5 % in cases and controls in the OKT area, and 44.9 and 56.5 % in cases and controls, in the DCO area, respectively. The declared SL conferred 40.5 % (95 % CI 22.2-54.5 %) and 55.5 % (95 % CI 28.2-72.4 %) protection against uncomplicated malaria in the OKT and the DCO areas, respectively. Significant differences in PE were observed according to the mother's education level. CONCLUSION: In the context of a mass distribution of LLIN, their use still conferred protection in up to 55 % against the occurrence of clinical malaria cases in children. Social factors, the poor use and the poor condition of an LLIN can be in disfavour with its effectiveness. In areas, where LLIN coverage is assumed to be universal or targeted at high-risk populations, case-control studies should be regularly conducted to monitor the effectiveness of LLIN. The findings will help National Malaria Control Programme and their partners to improve the quality of malaria control according to the particularity of each area or region as far as possible.

Inland valley rice production systems and malaria infection and disease in the forest region of western Côte d'Ivoire.

BACKGROUND: This study aimed to determine the epidemiological impact of rice cultivation in inland valleys on malaria in the forest region of western Côte d'Ivoire. The importance of malaria was compared in terms of prevalence and parasite density of infections and also in terms of clinical malaria incidence between three agro-ecosystems: (i) uncultivated inland valleys, (R0), (ii) inland valleys with one annual rice cultivation in the rainy season, (R1) and (iii) developed inland valleys with two annual rice cultivation cycles, (R2). METHODS: Between May 1998 and March 1999, seven villages of each agro-ecosystem (R0, R1 and R2) were randomly selected among villages pooled by farming system. In these 21 villages, a total of 1,900 people of all age groups were randomly selected and clinically monitored during one year. Clinical and parasitological information was obtained by active case detection of malaria episodes carried out during eight periods of five consecutive days scheduled at six weekly intervals and by cross-sectional surveys. RESULTS: Plasmodium falciparum was the principal parasite observed in the three agro-ecosystems. A level of holoendemicity of malaria was observed in the three agro-ecosystems with more than 75% of children less than 12 months old infected. Geometric mean parasite density in asymptomatic persons varied between 180 and 206 P. falciparum asexual forms per µL of blood and was associated with season and with age, but not with farming system. The mean annual malaria incidence rate reached 0.7 (95% IC 0.5-0.9) malaria episodes per person in R0, 0.7 (95% IC 0.6-0.9) in R1 and 0.6 (95% IC 0.5-0.7) in R2. The burden of malaria was the highest among children under two years of age, with at least four attacks by person-year. Then malaria incidence decreased by half in the two to four-year age group. From the age of five years, the incidence was lower than one attack by person-year. Malaria incidence varied with season with more cases in the rainy season than in the dry season but not with farming system. CONCLUSION: In the forest area of western Côte d'Ivoire, inland valley rice cultivation was not significantly associated with malaria burden.

First attempt to validate human IgG antibody response to Nterm-34kDa salivary peptide as biomarker for evaluating exposure to Aedes aegypti bites.

BACKGROUND: Much effort is being devoted for developing new indicators to evaluate the human exposure to Aedes mosquito bites and the risk of arbovirus transmission. Human antibody (Ab) responses to mosquito salivary components could represent a promising tool for evaluating the human-vector contact. METHODOLOGY/PRINCIPAL FINDINGS: To develop a specific biomarker of human exposure to Aedes aegypti bites, we measured IgG Ab response to Ae. aegypti Nterm-34 kDa salivary peptide in exposed children in 7 villages of Southern Benin (West Africa). Results showed that specific IgG response presented high inter-individual heterogeneity between villages. IgG response was associated with rainfall and IgG level increased from dry (low exposure) to rainy (high exposure) seasons. These findings indicate that IgG Ab to Nterm-34 kDa salivary peptide may represent a reliable biomarker to detect variation in human exposure to Ae. aegypti bites. CONCLUSION/SIGNIFICANCE: This preliminary study highlights the potential use of Ab response to this salivary peptide for evaluating human exposure to Ae. aegypti. This biomarker could represent a new promising tool for assessing the risk of arbovirus transmission and for evaluating the efficacy of vector control interventions.

Combination of malaria vector control interventions in pyrethroid resistance area in Benin: a cluster randomised controlled trial.

BACKGROUND: Malaria control efforts and elimination in Africa are being challenged by the development of resistance of parasites to antimalarial drugs and vectors to insecticides. We investigated whether the combination of long-lasting insecticidal mosquito nets (LLINs) with indoor residual spraying (IRS) or carbamate-treated plastic sheeting (CTPS) conferred enhanced protection against malaria and better management of pyrethroid-resistance in vectors than did LLINs alone. METHODS: We did a cluster randomised controlled trial in 28 villages in southern Benin, west Africa. Inclusion criteria of the villages were moderate level of pyrethroid resistance in malaria vectors and minimum distance between villages of 2 km. We assessed four malaria vector control interventions: LLIN targeted coverage to pregnant women and children younger than 6 years (TLLIN, reference group), LLIN universal coverage of all sleeping units (ULLIN), TLLIN plus full coverage of carbamate-IRS applied every 8 months (TLLIN+IRS), and ULLIN plus full coverage of CTPS lined up to the upper part of the household walls (ULLIN+CTPS). The interventions were allocated to villages by a block randomisation on the basis of preliminary surveys and children of each village were randomly selected to participate with computer-generated numbers. The primary endpoint was the incidence density rate of Plasmodium falciparum clinical malaria in children younger than 6 years as was analysed by Poisson regression taking into account the effect of age and the sampling design with a generalised estimating equation approach. Clinical and parasitological information were obtained by active case detection of malaria episodes during 12 periods of 6 consecutive days scheduled at six weekly intervals and by cross-sectional surveys of asymptomatic plasmodial infections. Children or study investigators were not masked to study group. This study is registered with Current Controlled Trials, number ISRCTN07404145. FINDINGS: Of 58 villages assessed, 28 were randomly assigned to intervention groups. 413-429 children were followed up in each intervention group for 18 months. The clinical incidence density of malaria was not reduced in the children from the ULLIN group (incidence density rate 0·95, 95% CI 0·67-1·36, p=0·79), nor in those from the TLLIN+IRS group (1·32, 0·90-1·93, p=0·15) or from the ULLIN+CTPS group (1·05, 0·75-1·48, p=0·77) compared with the reference group (TLLIN). The same trend was observed with the prevalence and parasite density of asymptomatic infections (non significant regression coefficients). INTERPRETATION: No significant benefit for reducing malaria morbidity, infection, and transmission was reported when combining LLIN+IRS or LLIN+CTPS compared with a background of LLIN coverage. These findings are important for national malaria control programmes and should help the design of more cost-effective strategies for malaria control and elimination. FUNDING: Ministère Français des Affaires Etrangères et Européennes (FSP project 2006-22), Institut de Recherche pour le Développement, President's Malaria Initiative (PMI) of US Governement.

Impact of prenatal multiple micronutrients on survival and growth during infancy: a randomized controlled trial.

BACKGROUND: Although prenatal multiple micronutrients can improve fetal growth, their benefit on postnatal health remains uncertain. OBJECTIVE: We assessed the effect of the UNICEF/WHO/United Nations University multiple micronutrient supplement for pregnant and lactating women (UNIMMAP) compared with the usual iron and folic acid supplement (IFA) on survival, growth, and morbidity during infancy. DESIGN: In a double-blind, randomized trial, we followed 1294 singleton newborns whose mothers had prenatally received either the UNIMMAP or IFA. We assessed monthly anthropometric measures and health variables up to age 12 mo. Children were assessed again at a mean age of 30 mo. Mixed-effects models accounted for repeated measurements. RESULTS: The UNIMMAP resulted in a 27% (HR: 0.73; 95% CI: 0.60, 0.87; P = 0.002) reduction in the rate of stunting in 15,261 infant-months with a higher length-for-age z score of 0.13 (95% CI: 0.02, 0.24; P = 0.02) over the whole observation period. However, by age 30 mo, this difference was not observed. An effect of the UNIMMAP on weight-for-length (P-interaction = 0.004) and head circumference-for-age (P-interaction = 0.03) became apparent by the end of the first year of life. By the age of 30 mo, children from the UNIMMAP group had a higher weight-for-height z score of 0.20 (95% CI: 0.06, 0.34; P = 0.004). No difference in mortality or morbidity was identified in groups, except a 14% reduction in reported episodes of fever (95% CI: 1%, 28%; P = 0.04). CONCLUSIONS: Improved linear fetal growth with continuation into early life and enhanced postnatal growth were 2 mechanisms that mediated the effect of the prenatal UNIMMAP on infant nutritional status. Additional follow-up to assess long-term effects is warranted.

Dry season determinants of malaria disease and net use in Benin, West Africa.

BACKGROUND: To achieve malaria eradication, control efforts have to be sustained even when the incidence of malaria cases becomes low during the dry season. In this work, malaria incidence and its determinants including bed net use were investigated in children of under 5 years of age in 28 villages in southern Benin during the dry season. METHODS AND FINDINGS: Mean malaria clinical incidence was measured in children aged 0-5 years by active case detection in 28 villages of the Ouidah-Kpomasse-Tori Bossito sanitary district between November 2007 and March 2008. Using Poisson mixed-effect models, malaria incidence was assessed according to the level of transmission by different vector species, and Long-Lasting Insecticide-treated mosquito Nets (LLIN) use and ownership. Then, a Binomial mixed-effect model was developed to assess whether nighttime temperature (derived from MODIS remote sensing data), biting nuisance and LLIN ownership are good predictors of LLIN use >60%. Results suggested that Anopheles funestus (Incidence Rates Ratio (IRR) = 3.38 [IC95 1.91-6]) rather than An. gambiae s.s. is responsible for malaria transmission. A rate of LLIN use >60% was associated with a lower risk of malaria (IRR = 0.6 [IC95 0.37-0.99]). Low nocturnal temperature and high biting nuisance were good predictors of LLIN use >60%. CONCLUSIONS: As recommended by the Malaria Eradication (MalERA) Consultative Group on Modelling, there is a need to understand better the effects of seasonality on malaria morbidity. This study highlights the need to take into account the specificity of malaria epidemiology during the dry-hot season and get a better understanding of the factors that influence malaria incidence and net use. These findings should help National Malaria Control Programmes to implement more effective and sustainable malaria control strategies in Africa.

Prenatal micronutrient supplements cumulatively increase fetal growth.

Prenatal multiple micronutrients (UNIMMAP) improve fetal growth only moderately compared to iron and folic acid alone (IFA). Whether this is due to insufficient amounts of UNIMMAP or to IFA being in reality an active control is unknown. We assessed the association between cumulative micronutrient intake (CMI) and fetal growth by secondary analysis of a randomized controlled trial in Burkina Faso where tablet intake was directly observed. We applied 2-part residual regression models adjusted for main confounders. Among the 1056 single pregnancies included, the mean CMI (± SD) was 124 ± 54 tablets. The odds of delivering a small-for-gestational-age baby was reduced by 21% [(95%CI: 5, 35); P = 0.013] for each additional tertile of CMI. The association between CMI and birth weight was positively modified by gestational age at enrollment (P-interaction = 0.001). Each unit of CMI was associated with a 1.6-g [(95%CI: 0.3, 3.1); P = 0.019] higher birth weight at a mean-centered gestational age at enrollment, with a higher gradient observed later in pregnancy. Maternal BMI at enrollment was also a positive modifying factor (P-interaction = 0.02), with no association of CMI with birth weight for low BMI. There was no evidence of an effect modification by group allocation; i.e., we observed the same change in birth weight per unit of CMI with either IFA or UNIMMAP. Yet UNIMMAP increased birth weight by 69 g [(95%CI: 58, 81); P < 0.001] relative to IFA. We found similar results for thoracic and cephalic circumferences. In conclusion, for both IFA and UNIMMAP, the effect on fetal growth is cumulative. The supplementation should therefore begin as early as possible in pregnancy, even if the growth increment per CMI is higher in late than in early pregnancy. Women with a low BMI should also receive extra energy.

Randomized controlled trial of 2 prenatal iron supplements: is there a dose-response relation with maternal hemoglobin?

BACKGROUND: The most appropriate dose of iron to prevent maternal anemia is still unclear. OBJECTIVE: We assessed the dose-response relation between maternal hemoglobin and 2 prenatal iron supplements. DESIGN: An intention-to-treat, double-blind, randomized controlled trial compared 30 mg Fe + folic acid and 13 other micronutrients (UNIMMAP; UNICEF/WHO/UNU multiple micronutrient supplement for pregnant and lactating women) with 60 mg Fe + folic acid (IFA) only in rural Burkina Faso. Home visitors directly observed tablet intake. Mixed-effects models were used for the data analysis. RESULTS: At inclusion, 43.2% of the 1268 participants were anemic. On average, the hemoglobin concentration decreased over gestation by 0.019 g/dL (95% CI: 0.012, 0.025 g/dL) per week in the IFA and UNIMMAP groups. An increment in hemoglobin concentration per micronutrient tablet [ß (±SE) = 0.006 ± 0.001 g/dL; P < 0001] was observed only in women who were anemic at inclusion, whereas a decrease was observed in the other mothers (-0.003 ± 0.001 g/dL; P = 0.002, P for interaction < 0.0001); the finding was similar in both the IFA and UNIMMAP groups. Women with baseline anemia achieved the same hemoglobin concentration (mean ± SD: 11.1 ± 0.64 g/dL) as their counterparts who received ±180 tablets of either UNIMMAP or IFA. Despite this, micronutrient intake did not significantly prevent anemia (51.0% in the third trimester). It was, however, a risk factor for hemoconcentration (odds ratio per tertile of tablet intake: 2.10; 95% CI: 1.12, 3.94), independently of supplement type or initial hemoglobin concentration. CONCLUSIONS: UNIMMAP triggered the same hemoglobin dose response with half the amount of iron as provided by IFA treatment. The benefit of iron supplements in nonanemic women is unclear. Despite micronutrient supplementation, anemia remained highly prevalent during gestation, partly because of physiologic hemodilution. This trial was registered at clinicaltrials.gov as NCT00642408.

Prevention and control of malaria and sleeping sickness in Africa: where are we and where are we going?

The International Symposium on Malaria and Human African Trypanosomiasis: New Strategies for their Prevention & Control was held 7-8 October, 2010 in Cotonou, Benin with about 250 participants from 20 countries. This scientific event aimed at identifying the gaps and research priorities in the prevention and control of malaria and sleeping sickness in Africa and to promote exchange between North and South in the fields of medical entomology, epidemiology, immunology and parasitology. A broad range of influential partners from academia (scientists), stakeholders, public health workers and industry attempted the meeting and about 40 oral communications and 20 posters were presented by phD students and internationally-recognized scientists from the North and the South. Finally, a special award ceremony was held to recognize efforts in pioneer work conducted by staff involved in the diagnostic of the Sleeping illness in West Africa with partnership and assistance from WHO and Sanofi-Aventis group.

Culicidae diversity, malaria transmission and insecticide resistance alleles in malaria vectors in Ouidah-Kpomasse-Tori district from Benin (West Africa): A pre-intervention study.

BACKGROUND: To implement an Insecticide Resistance Management (IRM) strategy through a randomized controlled trial (phase III), 28 villages were selected in southern Benin. No recent entomological data being available in these villages, entomological surveys were performed between October 2007 and May 2008, before vector control strategies implementation, to establish baseline data. METHODS: Mosquitoes were sampled by human landing collection (16 person-nights per village per survey per village) during 5 surveys. Mosquitoes were identified morphologically and by molecular methods. The Plasmodium falciparum circumsporozoïte indexes were measured by ELISA, and the entomological inoculation rates (EIRs) were calculated. Molecular detection of pyrethroid knock down resistance (Kdr) and of insensitive acetylcholinesterase were performed. RESULTS: 44,693 mosquitoes belonging to 28 different species were caught from October 2007 to May 2008. Among mosquitoes caught, 318 were An. gambiae s.s., 2 were An. nili, 568 were An. funestus s.s., and one individual was An. leesoni. EIR was 2.05 ± 1.28 infective bites per human per 100 nights on average, of which 0.67 ± 0.60 were from An. funestus and 1.38 ± 0.94 infective bites were from An. gambiae. Important variations were noted between villages considering mosquito density and malaria transmission indicating a spatial heterogeneity in the study area. The kdr allelic frequency was 28.86% in An. gambiae s.s. on average and significantly increases from October 2007 (10.26%) to May 2008 (33.87%) in M molecular form of An. gambiae s.s. Ace 1 mutation was found in S molecular of An. gambiae s.s at a low frequency (< 1%). CONCLUSION: This study updates information on mosquito diversity and malaria risk in rural villages from south Benin. It showed a high spatial heterogeneity in mosquito distribution and malaria transmission and underlines the need of further investigations of biological, ecological, and behavioral traits of malaria vectors species and forms. This study is a necessary prerequisite to cartography malaria risk and to improve vector control operations in southern Benin.

Effect of maternal multiple micronutrient supplements on cord blood hormones: a randomized controlled trial.

BACKGROUND: Fetal growth improves in pregnant women who take daily maternal multiple micronutrients [United Nations International Multiple Micronutrient Preparation (UNIMMAP)] rather than iron and folic acid (IFA) alone. OBJECTIVE: Our objective was to test whether such an effect was mediated by changes in concentrations of cord hormones. DESIGN: In a double-blind, controlled trial carried out in Burkina Faso, we randomly assigned 1426 pregnant women to receive UNIMMAP or IFA supplements. We measured concentrations of insulin-like growth factor I (IGF-I), leptin, insulin, free thyroxine, and cortisol in cord serum in a subsample of 294 live single newborns. We performed mediation analysis with an Aroian test. RESULTS: UNIMMAP supplementation had no significant effect on cord hormone concentrations. However, UNIMMAP supplementation significantly affected concentrations of IGF-I (+30%; 95% CI: 8%, 52%; P = 0.009) and leptin in male newborns. In these infants, 51.1% (P = 0.08) of the effect of UNIMMAP supplementation on birth weight was mediated through IGF-I, whereas for female newborns, this proportion was negligible. UNIMMAP supplementation also increased cortisol concentrations by 36% (P = 0.009) in cord blood in primiparae (P for interaction = 0.02). Growth-retarded infants had 41.2% lower IGF-I (P < 0.0001) and 27.3% lower leptin (P = 0.04) than did infants with normal growth. Offspring of primiparae had reduced IGF-I and insulin concentrations, and their cortisol concentrations were 25% higher (P = 0.05). Male newborns had lower concentrations of IGF-I, leptin, and insulin than did female newborns. CONCLUSIONS: UNIMMAP supplementation had sex-specific effects on cord IGF-I and leptin concentrations that were of unclear clinical significance. Other pathways may have been involved in the action of UNIMMAP on fetal growth. The specific hormonal pattern in primiparae could be related to constrained fetal growth. Confirmatory studies are warranted. This trial was registered at clinicaltrials.gov as NCT00642408.

Malaria infection and disease in an area with pyrethroid-resistant vectors in southern Benin.

BACKGROUND: This study aimed to investigate baseline data on malaria before the evaluation of new vector control strategies in an area of pyrethroid-resistance of vectors. The burden of malaria was estimated in terms of infection (prevalence and parasite density) and of clinical episodes. METHODS: Between December 2007 and December 2008 in the health district of Ouidah-Kpomassè-Tori Bossito (southern Benin), a descriptive epidemiological survey of malaria was conducted. From 28 selected villages, seven were randomized from which a total of 440 children aged 0 to 5 years were randomly selected. Clinical and parasitological information was obtained by active case detection of malaria episodes carried out during eight periods of six consecutive days scheduled at six weekly intervals and by cross-sectional surveys of asymptomatic infection. Entomological information was also collected. The ownership, the use and the correct use of long-lasting insecticide-treated nets (LLINs) were checked over weekly-survey by unannounced visits at home in the late evening. RESULTS: Mean parasite density in asymptomatic children was 586 P. falciparum asexual forms per µL of blood (95%CI 504-680). Pyrogenic parasite cut-off was estimated 2,000 P. falciparum asexual blood forms per µL. The clinical incidence of malaria was 1.5 episodes per child per year (95%CI 1.2-1.9). Parasitological and clinical variables did not vary with season. Anopheles gambiae s.l. was the principal vector closely followed by Anopheles funestus. Entomological inoculation rate was 5.3 (95%CI 1.1-25.9) infective bites per human per year. Frequency of the L1014F kdr (West) allele was around 50%. Annual prevalence rate of Plasmodium falciparum asymptomatic infection was 21.8% (95%CI 19.1-24.4) and increased according to age. Mean rates of ownership and use of LLINs were 92% and 70% respectively. The only correct use of LLINs (63%) conferred 26% individual protection against only infection (OR = 0.74 (95%IC 0.62-0.87), p = 0.005). CONCLUSION: The health district of Ouidah-Kpomassè-Tori Bossito is a mesoendemic area with a moderate level of pyrethroid-resistance of vectors. The used LLINs rate was high and only the correct use of LLINs was found to reduce malaria infection without influencing malaria morbidity.

Intermittent preventive treatment of malaria with sulphadoxine-pyrimethamine during pregnancy in Burkina Faso: effect of adding a third dose to the standard two-dose regimen on low birth weight, anaemia and pregnancy outcomes.

BACKGROUND: Intermittent preventive treatment with sulphadoxine-pyrimethamine (IPTp-SP) is being implemented in most malaria endemic countries as a standard two-doses regimen as it reduces the risk of low birth weight (LBW) and the prevalence of maternal anaemia. Nevertheless, where the risk of infection close to delivery is high because of intense transmission, a third IPTp-SP dose may further reduce the negative effects of malaria on pregnancy outcome. METHODS: Pregnant women in the 2nd or 3rd trimester were randomized to receive either 2 (SP2) or 3 doses (SP3) of SP. Trained field workers paid home visits to the women for drug administration according to a predefined drug delivery schedule. Women were encouraged to attend their scheduled ANC visits and to deliver at the health facilities where the new-born was weighed. The prevalence of LBW (<2500 g), severe anaemia (Hb < 8 g/dL) and premature birth was analysed using intention-to-treat (ITT) and per-protocol (PP) analysis. RESULTS: Data from 1274 singleton pregnancies were analysed (641 in the SP3 and 633 in the SP2 group). The uptake of the intervention appeared to be low. Though the prevalence of LBW in both intervention groups was similar (adjusted Incident Rate Ratio, AIRR = 0.92, 95%CI: 0.69-1.24) in the ITT analysis, the risk of severe anaemia was significantly lower in the SP3 group compared to the SP2 group (AIRR = 0.38, 95%CI: 0.16 - 0.90). The PP analysis showed a trend of reduced risk of LBW, severe anaemia and premature delivery in the SP3 group, albeit the difference between two and three IPTp-SP did not reach statistical significance. CONCLUSION: The risk of LBW and severe anaemia tended to be lower in the SP3 group, though this was not statistically significant, probably due to the low uptake of the intervention which reduced the power of the study. Further studies are needed for establishing whether a third SP dose has a real benefit in preventing the negative effects of malaria in pregnancy in settings where transmission is markedly seasonal.

Social and environmental malaria risk factors in urban areas of Ouagadougou, Burkina Faso.

BACKGROUND: Despite low endemicity, malaria remains a major health problem in urban areas where a high proportion of fevers are presumptively treated using anti-malarial drugs. Low acquired malaria immunity, behaviour of city-dwellers, access to health care and preventive interventions, and heterogenic suitability of urban ecosystems for malaria transmission contribute to the complexity of the malaria epidemiology in urban areas. METHODS: The study was designed to identify the determinants of malaria transmission estimated by the prevalence of anti-circumsporozoite (CSP) antibodies, the prevalence and density of Plasmodium falciparum infection, and the prevalence of malarial disease in areas of Ouagadougou, Burkina-Faso. Thick blood smears, dried blood spots and clinical status have been collected from 3,354 randomly chosen children aged 6 months to 12 years using two cross-sectional surveys (during the dry and rainy seasons) in eight areas from four ecological strata defined according to building density and land tenure (regular versus irregular). Demographic characteristics, socio-economic information, and sanitary and environmental data concerning the children or their households were simultaneously collected. Dependent variables were analysed using mixed multivariable models with random effects, taking into account the clustering of participants within compounds and areas. RESULTS: Overall prevalences of CSP-antibodies and P. falciparum infections were 7.7% and 16.6% during the dry season, and 12.4% and 26.1% during the rainy season, respectively, with significant differences according to ecological strata. Malaria risk was significantly higher among children who i) lived in households with lower economic or education levels, iii) near the hydrographic network, iv) in sparsely built-up areas, v) in irregularly built areas, vi) who did not use a bed net, vii) were sampled during the rainy season or ii) had traveled outside of Ouagadougou. CONCLUSION: Malaria control should be focused in areas which are irregularly or sparsely built-up or near the hydrographic network. Furthermore, urban children would benefit from preventive interventions (e.g. anti-vectorial devices or chemoprophylaxis) aimed at reducing malaria risk during and after travel in rural areas.

Effects of maternal multiple micronutrient supplementation on fetal growth: a double-blind randomized controlled trial in rural Burkina Faso.

BACKGROUND: Intrauterine growth retardation is a major predictor of child health in developing countries. OBJECTIVE: We tested whether providing pregnant women with the UNICEF/WHO/UNU international multiple micronutrient preparation (UNIMMAP), rather than iron and folic acid alone, improved fetal growth and its correlates. DESIGN: An intention-to-treat, double-blind, randomized controlled trial including 1426 pregnancies was carried out in rural Burkina Faso. Tablet intake was directly observed. RESULTS: Pregnancy outcome was known in 96.3% of the participants. After adjustment for gestational age at delivery, both birth weight (52 g; 95% CI: 4, 100; P = 0.035) and birth length (3.6 mm; 95% CI: 0.8, 6.3; P = 0.012) were significantly higher in the UNIMMAP group. UNIMMAP had a differential effect by percentiles of birth weight and length distributions: the risk of large-for-gestational-age infants was higher in the UNIMMAP group (OR: 1.58; 95% CI: 1.04, 2.38; P = 0.03), although the risk of low birth weight remained unchanged. The effect of UNIMMAP on birth size was modified by maternal body mass index at enrollment and could be more important in multiparous women and women taking sulfadoxine-pyrimethamine. Unexpectedly, the risk of perinatal death was marginally significantly increased in the UNIMMAP group (OR: 1.78; 95% CI: 0.95, 3.32; P = 0.07), and this seemed to affect mainly primiparous women (OR: 3.44; 95% CI: 1.1, 10.7; P for interaction = 0.11). CONCLUSIONS: Maternal UNIMMAP modestly but significantly increased fetal growth. The resulting benefit on infant growth and survival needs to be assessed. The possible lack of benefit and potential harm in primiparous women should be further investigated. This trial was registered at clinicaltrials.gov as NCT00642408.

Antimalarial drug use in general populations of tropical Africa.

BACKGROUND: The burden of Plasmodium falciparum malaria has worsened because of the emergence of chloroquine resistance. Antimalarial drug use and drug pressure are critical factors contributing to the selection and spread of resistance. The present study explores the geographical, socio-economic and behavioural factors associated with the use of antimalarial drugs in Africa. METHODS: The presence of chloroquine (CQ), pyrimethamine (PYR) and other antimalarial drugs has been evaluated by immuno-capture and high-performance liquid chromatography in the urine samples of 3,052 children (2-9 y), randomly drawn in 2003 from the general populations at 30 sites in Senegal (10), Burkina-Faso (10) and Cameroon (10). Questionnaires have been administered to the parents of sampled children and to a random sample of households in each site. The presence of CQ in urine was analysed as dependent variable according to individual and site characteristics using a random - effect logistic regression model to take into account the interdependency of observations made within the same site. RESULTS: According to the sites, the prevalence rates of CQ and PYR ranged from 9% to 91% and from 0% to 21%, respectively. In multivariate analysis, the presence of CQ in urine was significantly associated with a history of fever during the three days preceding urine sampling (OR = 1.22, p = 0.043), socio-economic level of the population of the sites (OR = 2.74, p = 0.029), age (2-5 y = reference level; 6-9 y OR = 0.76, p = 0.002), prevalence of anti-circumsporozoite protein (CSP) antibodies (low prevalence: reference level; intermediate level OR = 2.47, p = 0.023), proportion of inhabitants who lived in another site one year before (OR = 2.53, p = 0.003), and duration to reach the nearest tarmacked road (duration less than one hour = reference level, duration equal to or more than one hour OR = 0.49, p = 0.019). CONCLUSION: Antimalarial drug pressure varied considerably from one site to another. It was significantly higher in areas with intermediate malaria transmission level and in the most accessible sites. Thus, P. falciparum strains arriving in cross-road sites or in areas with intermediate malaria transmission are exposed to higher drug pressure, which could favour the selection and the spread of drug resistance.

Sequence analysis of Plasmodium falciparum cytochrome b in multiple geographic sites.

BACKGROUND: The antimalarial drug atovaquone specifically targets Plasmodium falciparum cytochrome b (Pfcytb), a mitochondrial gene with uniparental inheritance. Cases of resistance to atovaquone associated with mutant Pfcytb have been reported, justifying efforts to better document the natural polymorphism of this gene. To this end, a large molecular survey was conducted in several malaria endemic areas where atovaquone was not yet in regular use. METHODS: The polymorphism of the Pfcytb was analysed by direct sequencing of PCR products corresponding to the full length coding region. Sequence was generated for 671 isolates originating from three continents: Africa (Senegal, Ivory Coast, Central African Republic and Madagascar), Asia (Cambodia) and South America (French Guiana). RESULTS: Overall, 11 polymorphic sites were observed, of which eight were novel mutations. There was a large disparity in the geographic distribution of the mutants. All isolates from Senegal, Central African Republic and Madagascar displayed a Camp/3D7 wild type Pfcytb sequence, as did most samples originating from Cambodia and Ivory Coast. One synonymous (t759a at codon V253V) and two non-synonymous (t553g and a581g at codons F185V and H194R, respectively) singletons were detected in Ivory Coast. Likewise, two synonymous (a126t and c793t at codons -T42T and L265L, respectively) singletons were observed in Cambodia. In contrast, seven mutated sites, affecting seven codons and defining four mutant haplotypes were observed in French Guiana. The wild type allele was observed in only 14% of the French Guiana isolates. The synonymous c688t mutation at position L230L was highly prevalent; the most frequent allele was the c688t single mutant, observed in 84% of the isolates. The other alleles were singletons (a126t/a165c, a4g/a20t/a1024c and a20t/t341c/c688t corresponding to T42T/S55S, N2D/N71I/I342L, N71I/L114S/L230L, respectively" please replace with ' corresponding to T42T/S55S, N2D/N71I/I342L and N71I/L114S/L230L, respectively). The codon 268 polymorphisms associated with atovaquone resistance were not observed in the panel the isolates studied. Overall, the wild type PfCYTb protein isoform was highly predominant in all study areas, including French Guiana, suggesting stringent functional constraints. CONCLUSION: These data along with previously identified Pfcytb field polymorphisms indicate a clustering of molecular signatures, suggesting different ancestral types in South America and other continents. The absence of mutations associated with most atovaquone-proguanil clinical failures indicates that the atovaquone-proguanil association is an interesting treatment option in the study areas.