Does acute malnutrition in young children increase the risk of treatment failure following artemisinin-based combination therapy? A WWARN individual patient data meta-analysis

BACKGROUND

The geographical, demographic, and socioeconomic distributions of malaria and malnutrition largely overlap. It remains unknown whether malnutrition affects the efficacy of WHO-recommended artemisinin-based combination therapies (ACTs). A previous systematic review was inconclusive as data were sparse and heterogeneous, indicating that other methodological approaches, such as individual patient data meta-analysis, should be considered. The objective of this study was to conduct such a meta-analysis to assess the effect of malnutrition (wasting and stunting) on treatment outcomes in children younger than 5 years treated with an ACT for uncomplicated falciparum malaria.

METHODS

We conducted a meta-analysis of individual patient data from studies identified through a systematic review of literature published between 1980 and 2018 in PubMed, Global Health, and Cochrane Libraries (PROSPERO CRD42017056934) and inspection of the WorldWide Antimalarial Resistance Network (WWARN) repository for ACT efficacy studies, including children younger than 5 years with uncomplicated falciparum malaria. The association of either acute (wasting) or chronic (stunting) malnutrition with day 42 PCR-adjusted risk of recrudescence (ie, return of the same infection) or reinfection after therapy was investigated using Cox regression, and with day 2 parasite positivity using logistic regression.

FINDINGS

Data were included from all 36 studies targeted, 31 from Africa. Of 11 301 eligible children in 75 study sites, 11·5% were wasted (weight-for-height Z score [WHZ] <-2), and 31·8% were stunted (height-for-age Z score [HAZ] <-2). Decrease in WHZ was associated with increased risk of day 2 positivity (adjusted odds ratio 1·12, 95% CI 1·05-1·18 per unit; p=0·0002), treatment failure (adjusted hazard ratio [AHR] 1·14, 95% CI 1·02-1·26, p=0·016), and reinfection after therapy (AHR 1·09, 1·04-1·13, p=0·0003). Children with milder wasting (WHZ -2 to -1) also had a higher risk of recrudescence (AHR 1·85, 1·29-2·65, p=0·0008 vs WHZ ≥0). Stunting was not associated with reduced ACT efficacy.

INTERPRETATION

Children younger than 5 years with acute malnutrition and presenting with uncomplicated falciparum malaria were at higher risk of delayed parasite clearance, ACT treatment failure, and reinfections. Stunting was more prevalent, but not associated with changes in ACT efficacy. Acute malnutrition is known to impact medicine absorption and metabolism. Further study to inform dose optimisation of ACTs in wasted children is urgently needed.

FUNDING

Bill & Melinda Gates Foundation.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Facilitators and barriers to seasonal malaria chemoprevention (SMC) uptake in Nigeria: a qualitative approach

BACKGROUND

SMC was adopted in Nigeria in 2014 and by 2021 was being implemented in 18 states, over four months between June and October by 143000 community drug distributors (CDDs) to a target population of 23million children. Further expansion of SMC is planned, extending to 21 states with four or five monthly cycles. In view of this massive scale-up, the National Malaria Elimination Programme undertook qualitative research in five states shortly after the 2021 campaign to understand community attitudes to SMC so that these perspectives inform future planning of SMC delivery in Nigeria.

METHODS

In 20 wards representing urban and rural areas with low and high SMC coverage in five states, focus group discussions were held with caregivers, and in-depth interviews conducted with community leaders and community drug distributors. Interviews were also held with local government area and State malaria focal persons and at national level with the NMEP coordinator, and representatives of partners working on SMC in Nigeria. Interviews were recorded and transcribed, those in local languages translated into English, and transcripts analysed using NVivo software.

RESULTS

In total, 84 focus groups and 106 interviews were completed. Malaria was seen as a major health concern, SMC was widely accepted as a key preventive measure, and community drug distributors (CDDs) were generally trusted. Caregivers preferred SMC delivered door-to-door to the fixed-point approach, because it allowed them to continue daily tasks, and allowed time for the CDD to answer questions. Barriers to SMC uptake included perceived side-effects of SMC drugs, a lack of understanding of the purpose of SMC, mistrust and suspicions that medicines provided free may be unsafe or ineffective, and local shortages of drugs.

CONCLUSIONS

Recommendations from this study were shared with all community drug distributors and others involved in SMC campaigns during cascade training in 2022, including the need to strengthen communication about the safety and effectiveness of SMC, recruiting distributors from the local community, greater involvement of state and national level pharmacovigilance coordinators, and stricter adherence to the planned medicine allocations to avoid local shortages. The findings reinforce the importance of retaining door-to-door delivery of SMC.

Haematological consequences of acute uncomplicated falciparum malaria: a WorldWide Antimalarial Resistance Network pooled analysis of individual patient data

BACKGROUND

Plasmodium falciparum malaria is associated with anaemia-related morbidity, attributable to host, parasite and drug factors. We quantified the haematological response following treatment of uncomplicated P. falciparum malaria to identify the factors associated with malarial anaemia.

METHODS

Individual patient data from eligible antimalarial efficacy studies of uncomplicated P. falciparum malaria, available through the WorldWide Antimalarial Resistance Network data repository prior to August 2015, were pooled using standardised methodology. The haematological response over time was quantified using a multivariable linear mixed effects model with nonlinear terms for time, and the model was then used to estimate the mean haemoglobin at day of nadir and day 7. Multivariable logistic regression quantified risk factors for moderately severe anaemia (haemoglobin < 7 g/dL) at day 0, day 3 and day 7 as well as a fractional fall ≥ 25% at day 3 and day 7.

RESULTS

A total of 70,226 patients, recruited into 200 studies between 1991 and 2013, were included in the analysis: 50,859 (72.4%) enrolled in Africa, 18,451 (26.3%) in Asia and 916 (1.3%) in South America. The median haemoglobin concentration at presentation was 9.9 g/dL (range 5.0-19.7 g/dL) in Africa, 11.6 g/dL (range 5.0-20.0 g/dL) in Asia and 12.3 g/dL (range 6.9-17.9 g/dL) in South America. Moderately severe anaemia (Hb < 7g/dl) was present in 8.4% (4284/50,859) of patients from Africa, 3.3% (606/18,451) from Asia and 0.1% (1/916) from South America. The nadir haemoglobin occurred on day 2 post treatment with a mean fall from baseline of 0.57 g/dL in Africa and 1.13 g/dL in Asia. Independent risk factors for moderately severe anaemia on day 7, in both Africa and Asia, included moderately severe anaemia at baseline (adjusted odds ratio (AOR) = 16.10 and AOR = 23.00, respectively), young age (age < 1 compared to ≥ 12 years AOR = 12.81 and AOR = 6.79, respectively), high parasitaemia (AOR = 1.78 and AOR = 1.58, respectively) and delayed parasite clearance (AOR = 2.44 and AOR = 2.59, respectively). In Asia, patients treated with an artemisinin-based regimen were at significantly greater risk of moderately severe anaemia on day 7 compared to those treated with a non-artemisinin-based regimen (AOR = 2.06 [95%CI 1.39-3.05], p < 0.001).

CONCLUSIONS

In patients with uncomplicated P. falciparum malaria, the nadir haemoglobin occurs 2 days after starting treatment. Although artemisinin-based treatments increase the rate of parasite clearance, in Asia they are associated with a greater risk of anaemia during recovery.

Effectiveness of seasonal malaria chemoprevention (SMC) treatments when SMC is implemented at scale: Case-control studies in 5 countries

BACKGROUND

Seasonal malaria chemoprevention (SMC) has shown high protective efficacy against clinical malaria and severe malaria in a series of clinical trials. We evaluated the effectiveness of SMC treatments against clinical malaria when delivered at scale through national malaria control programmes in 2015 and 2016.

METHODS AND FINDINGS

Case-control studies were carried out in Mali and The Gambia in 2015, and in Burkina Faso, Chad, Mali, Nigeria, and The Gambia in 2016. Children aged 3-59 months presenting at selected health facilities with microscopically confirmed clinical malaria were recruited as cases. Two controls per case were recruited concurrently (on or shortly after the day the case was detected) from the neighbourhood in which the case lived. The primary exposure was the time since the most recent course of SMC treatment, determined from SMC recipient cards, caregiver recall, and administrative records. Conditional logistic regression was used to estimate the odds ratio (OR) associated with receipt of SMC within the previous 28 days, and SMC 29 to 42 days ago, compared with no SMC in the past 42 days. These ORs, which are equivalent to incidence rate ratios, were used to calculate the percentage reduction in clinical malaria incidence in the corresponding time periods. Results from individual countries were pooled in a random-effects meta-analysis. In total, 2,126 cases and 4,252 controls were included in the analysis. Across the 7 studies, the mean age ranged from 1.7 to 2.4 years and from 2.1 to 2.8 years among controls and cases, respectively; 42.2%-50.9% and 38.9%-46.9% of controls and cases, respectively, were male. In all 7 individual case-control studies, a high degree of personal protection from SMC against clinical malaria was observed, ranging from 73% in Mali in 2016 to 98% in Mali in 2015. The overall OR for SMC within 28 days was 0.12 (95% CI: 0.06, 0.21; p < 0.001), indicating a protective effectiveness of 88% (95% CI: 79%, 94%). Effectiveness against clinical malaria for SMC 29-42 days ago was 61% (95% CI: 47%, 72%). Similar results were obtained when the analysis was restricted to cases with parasite density in excess of 5,000 parasites per microlitre: Protective effectiveness 90% (95% CI: 79%, 96%; P<0.001), and 59% (95% CI: 34%, 74%; P<0.001) for SMC 0-28 days and 29-42 days ago, respectively. Potential limitations include the possibility of residual confounding due to an association between exposure to malaria and access to SMC, or differences in access to SMC between patients attending a clinic and community controls; however, neighbourhood matching of cases and controls, and covariate adjustment, attempted to control for these aspects, and the observed decline in protection over time, consistent with expected trends, argues against a major bias from these sources.

CONCLUSIONS

SMC administered as part of routine national malaria control activities provided a very high level of personal protection against clinical malaria over 28 days post-treatment, similar to the efficacy observed in clinical trials. The case-control design used in this study can be used at intervals to ensure SMC treatments remain effective.

Impact of alternative treatment approach for cerebral toxoplasmosis among HIV/AIDS patients from a resource-poor setting in Burkina Faso

Cerebral toxoplasmosis is caused by the protozoan Toxoplasma gondii because of reactivation of latent tissue cysts in the Acquired Immunodeficiency Syndrome (AIDS) patients with severe immunosuppression. The objective of this study was to evaluate the benefit of co-trimoxazole in presumptive and prevention of cerebral toxoplasmosis in Human Immunodeficiency Virus (HIV)/AIDS patients at Bobo-Dioulasso Hospital in Burkina Faso from June 2012 to October 2014. ELISA and ELFA were performed on serum for the quantitative determination of IgG and IgM anti-T. gondii, respectively. The seroprevalence of toxoplasmosis was 29.3%. No IgM antibodies for T. gondii were found. Six patients with Toxoplasma-specific antibodies presented cerebral toxoplasmosis. All patients were infected by HIV-1 with the median of CD4+ T lymphocytes at 141 cells/μl. No patient was under antiretroviral therapy. No case of cerebral toxoplasmosis was noted in patients receiving co-trimoxazole in prevention. Presumptive treatment of cerebral toxoplasmosis with co-trimoxazole was effective in all patients with a significant clinical improvement in 83.3%. These results attest the benefit of cotrimoxazole in cerebral toxoplasmosis treatment in countries where drug resources are limited when sulfadiazine is not available. Ours finding highlight the importance of establishing toxoplasmosis chemoprophylaxis to HIV with severe immunosuppression patients and positive Toxoplasma serology.

Large-scale delivery of seasonal malaria chemoprevention to children under 10 in Senegal: an economic analysis

Seasonal Malaria Chemoprevention (SMC) is recommended for children under 5 in the Sahel and sub-Sahel. The burden in older children may justify extending the age range, as has been done effectively in Senegal. We examine costs of door-to-door SMC delivery to children up to 10 years by community health workers (CHWs). We analysed incremental financial and economic costs at district level and below from a health service perspective. We examined project accounts and prospectively collected data from 405 CHWs, 46 health posts, and 4 district headquarters by introducing questionnaires in advance and completing them after each monthly implementation round. Affordability was explored by comparing financial costs of SMC to relevant existing health expenditure levels. Costs were disaggregated by administration month and by health service level. We used linear regression models to identify factors associated with cost variation between health posts. The financial cost to administer SMC to 180 000 children over one malaria season, reaching ∼93% of children with all three intended courses of SMC was $234 549 (constant 2010 USD) or $0.50 per monthly course administered. Excluding research-participation incentives, the financial cost was $0.32 per resident (all ages) in the catchment area, which is 1.2% of Senegal's general government expenditure on health per capita. Economic costs were 18.7% higher than financial costs at $278 922 or $0.59 per course administered and varied widely between health posts, from $0.38 to $2.74 per course administered. Substantial economies of scale across health posts were found, with the smallest health posts incurring highest average costs per monthly course administered. SMC for children up to 10 is likely to be affordable, particularly where it averts substantial curative care costs. Estimates of likely costs and cost-effectiveness of SMC in other contexts must account for variation in average costs across delivery months and health posts.

Haemoglobin changes and risk of anaemia following treatment for uncomplicated falciparum malaria in sub-Saharan Africa

Background

Anaemia is common in malaria. It is important to quantitate the risk of anaemia and to distinguish factors related to the natural history of disease from potential drug toxicity.

Methods

Individual-patient data analysis based on nine randomized controlled trials of treatments of uncomplicated falciparum malaria from 13 sub-Saharan African countries. Risk factors for reduced haemoglobin (Hb) concentrations and anaemia on presentation and after treatment were analysed using mixed effect models.

Results

Eight thousand eight hundred ninety-seven patients (77.0% <5 years-old) followed-up through 28 days treated with artemisinin combination therapy (ACT, 90%, n = 7968) or non-ACT. At baseline, under 5’s had the highest risk of anaemia (77.6% vs. 32.8%) and higher parasitaemia (43,938 μl) than older subjects (2784 μl). Baseline anaemia increased the risk of parasitological recurrence.

Hb began to fall after treatment start. In under 5’s the estimated nadir was ~35 h (range 29–48), with a drop of −12.8% from baseline (from 9.8 g/dl to 8.7 g/dl, p = 0.001); in under 15’s, the mean Hb decline between day 0–3 was −4.7% (from 9.4 to 9.0 g/dl, p = 0.001). The degree of Hb loss was greater in patients with high pre-treatment Hb and parasitaemia and with slower parasite reduction rates, and was unrelated to age. Subsequently, Hb increased linearly (+0.6%/day) until day 28, to reach +13.8% compared to baseline.

Severe anaemia (<5 g/dl, 2 per 1000 patients) was transient and all patients recovered after day 14, except one case of very severe anaemia associated with parasite recurrence at day 28.

There was no systematic difference in Hb concentrations between treatments and no case of delayed anaemia.

Conclusion

On presentation with acute malaria young children with high parasitaemia have the highest risk of anaemia. The majority of patients experience a drop in Hb while on treatment as early as day 1–2, followed by a linear increase through follow-up. The degree of the early Hb dip is determined by pre-treatment parasitaemia and parasite clearance rates. Hb trends and rick of anaemia are independent of treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2530-6) contains supplementary material, which is available to authorized users.

A Phase 3, Double-Blind, Randomized Study of Arterolane Maleate-Piperaquine Phosphate vs Artemether-Lumefantrine for Falciparum Malaria in Adolescent and Adult Patients in Asia and Africa

BACKGROUND

Artemisinins, which are derived from plants, are subject to risk of supply interruption due to climatic changes. Consequently, an effort to identify a new synthetic antimalarial was initiated. A fixed-dose combination of arterolane maleate (AM), a new synthetic trioxolane, with piperaquine phosphate (PQP), a long half-life bisquinoline, was evaluated in patients with uncomplicatedPlasmodium falciparummalaria.

METHODS

In this multicenter, randomized, double-blind, comparative, parallel-group trial, 1072 patients aged 12-65 years withP. falciparummonoinfection received either AM-PQP (714 patients) once daily or artemether-lumefantrine (A-L; 358 patients) twice daily for 3 days. All patients were followed up until day 42.

RESULTS

Of the 714 patients in the AM-PQP group, 638 (89.4%) completed the study; of the 358 patients in the A-L group, 301(84.1%) completed the study. In both groups, the polymerase chain reaction corrected adequate clinical and parasitological response (PCR-corrected ACPR) on day 28 in intent-to-treat (ITT) and per-protocol (PP) populations was 92.86% and 92.46% and 99.25% and 99.07%, respectively. The corresponding figures on day 42 in the ITT and PP populations were 90.48% and 91.34%, respectively. After adjusting for survival ITT, the PCR-corrected ACPR on day 42 was >98% in both groups. The overall incidence of adverse events was comparable.

CONCLUSIONS

AM-PQP showed comparable efficacy and safety to A-L in the treatment of uncomplicatedP. falciparummalaria in adolescent and adult patients. AM-PQP demonstrated high clinical and parasitological response rates as well as rapid parasite clearance.

CLINICAL TRIALS REGISTRATION

India. CTRI/2009/091/000101.

[Identification of anopheles breeding sites in the residual foci of low malaria transmission «hotspots» in Central and Western Senegal]

Malaria incidence has markedly declined in the Mbour, Fatick, Niakhar and Bambey districts (central and western Senegal) thanks to a scaling up of effective control measures namely LLINs (Long Lasting Insecticide Treated Net), ACTs (Artesunate Combination Therapy) and promoting care seeking. However malaria cases are now maintained by foci of transmission called hotspots. We evaluate the role of anopheles breeding sites in the identification of malaria hotspots in the health districts of Mbour, Fatick, Niakhar and Bambey. Surveys of breeding sites were made in 6 hotspot villages and 4 non-hotspot villages. A sample was taken in each water point with mosquito larvae by dipping method and the collected specimens were identified to the genus level. Additional parameters as name of the village and breeding sites, type of collection, original water turbidity, presence of vegetation, proximity to dwellings, geographic coordinates, sizes were also collected. Sixty-two water collections were surveyed and monitored between 2013 and 2014. Temporary natural breeding sites were predominant regardless of the epidemiological status of the village. Among the 31 breeding sites located within 500 meters of dwellings in hotspots villages, 70% carried Anopheles larvae during the rainy season while 43% of the 21 breeding sites located at similar distances in non-hotspot villages carried Anopheles larvae during the same period (P = 0.042). At the end of the rainy season, the trend is the same with 27% of positive breeding sites in hotspots and 14% in non-hotspots villages. The breeding sites encountered in hotspots villages are mostly small to medium size and are more productive by Anopheles larvae than those found in non-hotspot area. This study showed that the high frequency of smallest and productive breeding sites around and inside the villages can create conditions of residual transmission.

The effect of dosing strategies on the therapeutic efficacy of artesunate-amodiaquine for uncomplicated malaria: a meta-analysis of individual patient data

BACKGROUND

Artesunate-amodiaquine (AS-AQ) is one of the most widely used artemisinin-based combination therapies (ACTs) to treat uncomplicated Plasmodium falciparum malaria in Africa. We investigated the impact of different dosing strategies on the efficacy of this combination for the treatment of falciparum malaria.

METHODS

Individual patient data from AS-AQ clinical trials were pooled using the WorldWide Antimalarial Resistance Network (WWARN) standardised methodology. Risk factors for treatment failure were identified using a Cox regression model with shared frailty across study sites.

RESULTS

Forty-three studies representing 9,106 treatments from 1999-2012 were included in the analysis; 4,138 (45.4%) treatments were with a fixed dose combination with an AQ target dose of 30 mg/kg (FDC), 1,293 (14.2%) with a non-fixed dose combination with an AQ target dose of 25 mg/kg (loose NFDC-25), 2,418 (26.6%) with a non-fixed dose combination with an AQ target dose of 30 mg/kg (loose NFDC-30), and the remaining 1,257 (13.8%) with a co-blistered non-fixed dose combination with an AQ target dose of 30 mg/kg (co-blistered NFDC). The median dose of AQ administered was 32.1 mg/kg [IQR: 25.9-38.2], the highest dose being administered to patients treated with co-blistered NFDC (median = 35.3 mg/kg [IQR: 30.6-43.7]) and the lowest to those treated with loose NFDC-25 (median = 25.0 mg/kg [IQR: 22.7-25.0]). Patients treated with FDC received a median dose of 32.4 mg/kg [IQR: 27-39.0]. After adjusting for reinfections, the corrected antimalarial efficacy on day 28 after treatment was similar for co-blistered NFDC (97.9% [95% confidence interval (CI): 97.0-98.8%]) and FDC (98.1% [95% CI: 97.6%-98.5%]; P = 0.799), but significantly lower for the loose NFDC-25 (93.4% [95% CI: 91.9%-94.9%]), and loose NFDC-30 (95.0% [95% CI: 94.1%-95.9%]) (P < 0.001 for all comparisons). After controlling for age, AQ dose, baseline parasitemia and region; treatment with loose NFDC-25 was associated with a 3.5-fold greater risk of recrudescence by day 28 (adjusted hazard ratio, AHR = 3.51 [95% CI: 2.02-6.12], P < 0.001) compared to FDC, and treatment with loose NFDC-30 was associated with a higher risk of recrudescence at only three sites.

CONCLUSIONS

There was substantial variation in the total dose of amodiaquine administered in different AS-AQ combination regimens. Fixed dose AS-AQ combinations ensure optimal dosing and provide higher antimalarial treatment efficacy than the loose individual tablets in all age categories.

[Profile of cytokines associated with protection against malaria episodes during pregnancy in hypo-endemic area in Senegal]

Malarial infection in non immune pregnant women is a major risk factor for pregnancy failure. However in malaria endemic areas, intermittent preventive treatment (IPTp) have been adopted to prevent malaria in pregnancy women since 2003 in Senegal. The impact of IPT on the development of immunity is not very well documented. We conducted a prospective study at the Roi-Baudouin maternity hospital of Guediawaye in Senegal to assess IL10, IL12, TNFα and IFNγ cytokines production in pregnant women under IPTp. Cytokines were analyzed in 82 sera at inclusion and delivery. P. falciparum HRP2 antigen was detected in 17% of women included by rapid diagnostic test (RDT). At inclusion the mean of IL10 response was higher in P. falciparum negative women (8 UA) compare to RDT-positive women (7 UA) p=0.069 while in delivery the opposite was found p=0.014. Low production of inflammatory cytokines IL12, IFNγ and TNFα was noted in both groups. Between inclusion and delivery, a significant increase of IL-10 production was noted while a decrease of IFNγ and TNFα cytokine was noted. Thus, IL12 and IFNγ responses may synergistically associate as malaria immune response during pregnancy.

Plasmodium falciparum clearance in clinical studies of artesunate-amodiaquine and comparator treatments in sub-Saharan Africa, 1999-2009

BACKGROUND

Artemisinin-based combination therapy (ACT) is the recommended first-line therapy for uncomplicated Plasmodium falciparum malaria worldwide but decreased artemisinin susceptibility, phenotypically characterized as slow parasite clearance time (PCT), has now been reported in Southeast Asia. This makes it all too important to measure the dynamics of parasite clearance in African patients treated with ACT over time, to understand trends and detect changes early enough to intervene

METHODS

Individual patient data from 27 clinical trials of artesunate-amodiaquine (ASAQ) vs comparators conducted between 1999 and 2009 were analysed for parasite clearance on modified intent-to-treat (ITT) basis.

RESULTS

Overall 15,017 patients treated for uncomplicated P. falciparum malaria at 44 sites in 20 sub-Saharan African countries were included in the analysis; 51% (n=7,660) vs 49% (n=7,357) were treated with ASAQ and comparator treatments, respectively. Seventy-seven per cent (77%) were children under six years of age. The proportion of the patients treated with ASAQ with persistent parasitaemia on Day 2 was 8.6%, and 1.5% on Day 3. Risk factor for not clearing parasites on Day 2 and Day 3 calculated by multivariate logistic regression with random effect on site and controlling for treatment were: high parasitaemia before treatment was (adjusted risk ratios (AOR) 2.12, 95% CI 1.91-2.35, AOR 2.43, 95% CI 1.98-3.00, respectively); non-ACT treatment (p=0.001, for all comparisons). Anaemia (p=0.001) was an additional factor for Day 2 and young age (p=0.005) for Day 3.In patients treated with ASAQ in studies who had complete parasitaemia data every 24 hours up to Day 3 and additionally Day 7, the parasite reduction ratio was 93.9% by Day 1 and 99.9% by Day 2. Using the median parasitaemia before treatment (p0=27,125 μL) and a fitted model, the predicted PCT (pPCT = 3.614*ln (p0) - 6.135, r(2) = 0.94) in ASAQ recipients was 31 hours.

CONCLUSION

Within the period covered by these studies, rapid Plasmodium falciparum clearance continues to be achieved in Sub-Saharan African patients treated with ACT, and in particular with ASAQ. The prediction formula for parasite clearance time could be a pragmatic tool for studies with binary outcomes and once-daily sampling, both for research and monitoring purposes.

[Cryptosporidiosis in Senegalese children: prevalence study and use of ELISA serologic diagnosis]

This is a prospective, descriptive and analytic study conducted from July 2011 to September 2011 at the Children National Hospital Albert Royer of Dakar and at the Vélingara Health District. It was focused on children under 15 without reference to HIV status. For each child, a sample of stool was examined by the Ziehl-Neelsen modified staining and by ELISA using the "Cryptosporidium Antigen Detection Microwell ELISA kit" designed to detect Cryptosporidium spp antigens. The aim of our study was to determine the prevalence of cryptosporidiosis in rural and hospital areas and to measure the performance of the ELISA kit that we used. Out of the 375 stool examinations performed with the Ziehl-Neelsen modified staining, 17 had revealed the presence of Cryptosporidium spp (4.53%). The prevalence in rural areas was 2% while the hospital prevalence was 7.4%, of which 1.8% (1/57) were from urban areas and 9.8% (12/122) from suburban areas. No positive case was observed in children over 10 years. By ELISA, 23 positives cases were reported corresponding to a prevalence of 6.13% (1.8% in children living in urban areas, 13.1% in children from suburban areas and 3%living in rural areas).The correlation of this assay with the Ziehl-Neelsen modified staining, considered as the reference method, found that this assay had a sensitivity of 58.82% and a high specificity reaching 96.37%. The positive predictive value (PPV) was 43.4% while the negative predictive value was 98%. Cryptosporidiosis is a significant cause of parasitic infection among children in Senegal. Antigen detection of Cryptosporidium spp by ELISA in stool can be a complementary tool in the diagnosis of cryptosporidiosis.

Safety monitoring of artemisinin combination therapy through a national pharmacovigilance system in an endemic malaria setting

Background

The National Malaria Control Programme in Senegal, introduced since 2006, artemisinin-based combination therapy (ACT administration) for the treatment of uncomplicated malaria cases. In this framework, an anti-malarial pharmacovigilance plan was developed and implemented in all public health services. This study investigated the occurrence of Adverse Drug Events (ADEs) after ACT.

Methods

The study was conducted between January 2007 and December 2009. It was based on spontaneous reports of ADEs in public health facilities. Data on patient demographic characteristics, dispensing facility, adverse signs and symptoms and causality were collected from a total of 123 patients.

Results

The age range of these patients was six months to 93 years with a mean of 25.9 years. Of the reported symptoms, 46.7% were related to the abdomen and the digestive system. Symptoms related to the nervous system, skin and subcutaneous tissue, circulatory and respiratory systems and general symptoms and signs were 7%, 9.7%, 3.5% and 31.3%, respectively. Causality results linked 14.3% of symptoms to Falcimon® (Artesunate-Amodiaquine) with certainty. Effects were classified as mild and severe in 69.1% and 7.3% of cases respectively while 23.6% were serious. All patients with serious ADEs were hospitalized. One death was reported in a patient who had taken 24 pills at once.

Conclusion

These results confirm the need to develop and implement pharmacovigilance systems in malaria endemic countries in order to monitor the safety of anti-malarial treatments.

Clinical tolerability of artesunate-amodiaquine versus comparator treatments for uncomplicated falciparum malaria: an individual-patient analysis of eight randomized controlled trials in sub-Saharan Africa

BACKGROUND

The widespread use of artesunate-amodiaquine (ASAQ) for treating uncomplicated malaria makes it important to gather and analyse information on its tolerability.

METHODS

An individual-patient tolerability analysis was conducted using data from eight randomized controlled clinical trials conducted at 17 sites in nine sub-Saharan countries comparing ASAQ to other anti-malarial treatments. All patients who received at least one dose of the study drug were included in the analysis. Differences in adverse event (AE) and treatment emergent adverse event (TEAE) were analysed by Day 28.

RESULTS

Of the 6,179 patients enrolled (74% <5 years of age), 50% (n = 3,113) received ASAQ, 20% (n = 1,217) another ACT, and 30% (n = 1,849) a non-ACT (combination or single-agent) treatment. Overall, 8,542 AEs were recorded. The proportion of patients experiencing at least one gastro-intestinal AE on ASAQ was 43% (and higher than that with artemether-lumefantrine and dihydroartemisinin-piperaquine at two sites), and was 23% for any other AEs (not different from other treatments). Specifically, the risk of diarrhoea, vomiting, cough and weakness was lower with artemether-lumefantrine; artemether-lumefantrine and dihydroartemisinin-piperaquine carried a higher risk of pruritus, chloroquine-SP had a higher risk of nausea. Parasitological recurrence increased the risk of occurrence of any AE. No other difference was detected. Comparing AE to TEAE in patients who had pre-treatment occurrence and grades of intensity recorded, AEs were significantly more related to the pre-treatment prevalence of the symptom (p = 0.001, Fisher test); AEs overestimated TEAEs by a factor ranging from none to five-fold. The overall incidence of serious AEs (SAEs) with ASAQ was nine per 1,000 (29/3,113) and mortality was one per 1,000 (three deaths, none drug-related); both were similar to other treatments.

CONCLUSION

ASAQ was comparatively well-tolerated. Safety information is important, and must be collected and analysed in a standardized way. TEAEs are a more objective measure of treatment-induced toxicity.

Sahel, savana, riverine and urban malaria in West Africa: Similar control policies with different outcomes

The study sites for the West African ICEMR are in three countries (The Gambia, Senegal, Mali) and are located within 750 km of each other. In addition, the National Malaria Control Programmes of these countries have virtually identical policies: (1) Artemisinin Combination Therapies (ACTs) for the treatment of symptomatic Plasmodium falciparum infection, (2) Long-Lasting Insecticide-treated bed Nets (LLINs) to reduce the Entomololgic Inoculation Rate (EIR), and (3) sulfadoxine-pyrimethamine for the Intermittent Preventive Treatment of malaria during pregnancy (IPTp). However, the prevalence of P. falciparum malaria and the status of malaria control vary markedly across the four sites with differences in the duration of the transmission season (from 4-5 to 10-11 months), the intensity of transmission (with EIRs from unmeasurably low to 4-5 per person per month), multiplicity of infection (from a mean of 1.0 to means of 2-5) and the status of malaria control (from areas which have virtually no control to areas that are at the threshold of malaria elimination). The most important priority is the need to obtain comparable data on the population-based prevalence, incidence and transmission of malaria before new candidate interventions or combinations of interventions are introduced for malaria control.

Improving malaria control in West Africa: interruption of transmission as a paradigm shift

With the paradigm shift from the reduction of morbidity and mortality to the interruption of transmission, the focus of malaria control broadens from symptomatic infections in children ≤5 years of age to include asymptomatic infections in older children and adults. In addition, as control efforts intensify and the number of interventions increases, there will be decreases in prevalence, incidence and transmission with additional decreases in morbidity and mortality. Expected secondary consequences of these changes include upward shifts in the peak ages for infection (parasitemia) and disease, increases in the ages for acquisition of antiparasite humoral and cellular immune responses and increases in false-negative blood smears and rapid diagnostic tests. Strategies to monitor these changes must include: (1) studies of the entire population (that are not restricted to children ≤5 or ≤10 years of age), (2) study sites in both cities and rural areas (because of increasing urbanization across sub-Saharan Africa) and (3) innovative strategies for surveillance as the prevalence of infection decreases and the frequency of false-negative smears and rapid diagnostic tests increases.

Comparing changes in haematologic parameters occurring in patients included in randomized controlled trials of artesunate-amodiaquine vs single and combination treatments of uncomplicated falciparum in sub-Saharan Africa

BACKGROUND

Artesunate-amodiaquine (AS&AQ) is a widely used artemisinin combination therapy (ACT) for falciparum malaria. A comprehensive appreciation of its effects on haematology vs other anti-malarials is needed in view of potential safety liabilities.

METHODS

Individual-patient data analysis conducted on a database from seven randomized controlled trials conducted in sub-Saharan African comparing AS&AQ to reference treatments in uncomplicated falciparum malaria patients of all ages. Haematologic values (white cells total and neutrophil counts, haemoglobin/haematocrit, platelets) were analysed as both continuous and categorical variables for their occurrence, (severity grade 1-4) and changes during follow-up. Risks and trends were calculated using multivariate logistic random effect models.

RESULTS

4,502 patients (72% < 5 years old), from 13 sites in nine countries with 28-day follow-up were treated with AS&AQ (45%) or a comparator (other forms of ACT accounted for 27%, other combination 12%, mono-therapies 16%). Pre-treatment leucopaenia (3%) and neutropaenia (6%) were infrequent; anaemia was common (39%). The treatment-emergent adverse events incidence (TEAE = condition not present or less severe pre-treatment) was 11% for neutropaenia, 6% for thrombocytopaenia with AS&AQ and not different from treatment groups; anaemia was higher with AS&AQ (20%) or other forms of ACT (22%) than in non-artemisinin groups (4%, p = 0.001). Multivariate analysis showed that the risk of anaemia, thrombocytopaenia, and leucopaenia decreased with follow-up time, while neutropaenia increased; the risk of anaemia and thrombocytopaenia increased with higher baseline parasitaemia and parasitological reappearance. White cells total count was not a good surrogate for neutropaenia. No systematic significant difference between treatments was detected. Older patients were at lower risks.

CONCLUSION

The effects of AS&AQ on haematologic parameters were not different from those of other anti-malarial treatments used in sub-Saharan Africa. This analysis provides the basis for a broader evaluation of haematology following anti-malarial treatment. Continuing monitoring of haematologic safety on larger databases is required.

Hematologic parameters in pediatric uncomplicated Plasmodium falciparum malaria in sub-Saharan Africa

Hematologic changes in acute and convalescent uncomplicated Plasmodium falciparum malaria have not been well studied, particularly in young children in Africa. Hematologic data were obtained for 3,044 children less than five years of age in seven randomized controlled trials at 14 sites. Using paired analysis between day 28 and baseline in patients without parasitologic failure as a proxy for malaria-induced effects, we found a statistically significant but clinically modest increase in leukocyte counts (5%) resulting from a larger increase in neutrophils (43%) than the decrease in lymphocytes counts (-16%); levels of hemoglobin and platelets decreased (-13% and -49%, respectively). Multivariate random effects analysis showed trends during follow-up (increased levels of hemoglobin, platelets and lymphocytes, and decreased levels of leukocytes and neutrophils) and identified explanatory variables. The risk of neutropenia increased with follow-up time independent of treatment outcome, and was lower with age, higher baseline parasitemia, and artemisinin combination treatment. These analyses provides information on hematologic variations caused by malaria.

Multicentric assessment of the efficacy and tolerability of dihydroartemisinin-piperaquine compared to artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in sub-Saharan Africa

Background

The choice of appropriate artemisinin-based combination therapy depends on several factors (cost, efficacy, safety, reinfection rate and simplicity of administration). To assess whether the combination dihydroartemisinin-piperaquine (DP) could be an alternative to artemether-lumefantrine (AL), the efficacy and the tolerability of the two products for the treatment of uncomplicated falciparum malaria in sub-Saharan Africa have been compared.

Methods

A multicentric open randomized controlled clinical trial of three-day treatment of DP against AL for the treatment of two parallel groups of patients aged two years and above and suffering from uncomplicated falciparum malaria was carried out in Cameroon, Côte d'Ivoire and Senegal. Within each group, patients were randomly assigned supervised treatment. DP was given once a day for three days and AL twice a day for three days. Follow-up visits were performed on day 1 to 4 and on day 7, 14, 21, 28 to evaluate clinical and parasitological results. The primary endpoint was the recovery rate by day 28.

Results

Of 384 patients enrolled, 197 were assigned DP and 187 AL. The recovery rates adjusted by genotyping, 99.5% in the DP group and 98.9% in the AL group, were not statistically different (p = 0.538). No Early Therapeutic Failure (ETF) was observed. At day 28, two patients in the DP group and five in AL group had recurrent parasitaemia with Plasmodium falciparum. In the DP group, after PCR genotyping, one of the two recurrences was classified as a new infection and the other as recrudescence. In AL group, two recurrences were classified after correction by PCR as recrudescence. All cases of recrudescence were classified as Late Parasitological Failure (LPF). In each group, a rapid recovery from fever and parasitaemia was noticed. More than 90% of patients did no longer present fever or parasitaemia 48 hours after treatment. Both drugs were well tolerated. Indeed, no serious adverse events were reported during the follow-up period. Most of the adverse events which developed were moderate and did not result in the treatment being stopped in either treatment group.

Conclusions

Dihydroartemisinin-piperaquine was as effective and well-tolerated as artemether-lumefantrine in the treatment of uncomplicated falciparum malaria. In addition, dihydroartemisinin-piperaquine, a single daily dose, could be an advantage over artemether-lumefantrine in Africa because of better treatment observance.

Standardised versus actual white cell counts in estimating thick film parasitaemia in African children under five

In patients with malaria, parasitaemia is usually estimated by assuming 8000 white cell counts (WCC) per microlitre of blood. In a sample of 3044 African children under 5 years of age with uncomplicated falciparum malaria, parasitaemia estimated using standardised WCC was compared to parasitaemia calculated based on each child's own WCC. The two methods produced comparable results. However, WCC were >8000 in under-fives with an inverse relationship with age, resulting in the standard approximation method significantly underestimating parasitaemia in the youngest age group and overestimating parasitaemia in the oldest age groups.

[Update on toxoplasmosis prevalence based on serological tests in pregnant women in Dakar, Senegal from 2002 to 2006]

The purpose of this study was to update data on toxoplasmosis antibody prevalence based on antenatal surveillance tests in pregnant women in Dakar, Senegal. The study population consisted of 941 pregnant women referred for diagnosis of toxoplasmosis in the Laboratory of Parasitology and Mycology at Le Dantec University Hospital Center from 2002 to 2006. Two tests using the solid-phase immunoenzymatic method were performed on venous blood samples collected at 3 weeks of interval (S1 and S2). This double testing technique was designed to detect increases in IgM and IgG antibody levels in order to confirm diagnosis of toxoplasmosis by ruling out immune response, acquired immunity or nonspecific antibody fixation. Comparison of S1 and S2 results in the 941 patients indicated a prevalence of 7.7% and 0% respectively for IgM+IgG- cases, 23.3% and 24.3% respectively for IgM+IgG-cases, and 11.3% and 10.2% respectively for IgM+IgG+ cases. The overall prevalence of toxoplasmosis antibodies was 34.5%. These data showing a high prevalence of toxoplasmosis among pregnant women in Dakar underscore the need to improve serological screening and follow up.

Efficacy of artesunate-amodiaquine for treating uncomplicated falciparum malaria in sub-Saharan Africa: a multi-centre analysis

BACKGROUND

Artesunate and amodiaquine (AS&AQ) is at present the world's second most widely used artemisinin-based combination therapy (ACT). It was necessary to evaluate the efficacy of ACT, recently adopted by the World Health Organization (WHO) and deployed over 80 countries, in order to make an evidence-based drug policy.

METHODS

An individual patient data (IPD) analysis was conducted on efficacy outcomes in 26 clinical studies in sub-Saharan Africa using the WHO protocol with similar primary and secondary endpoints.

RESULTS

A total of 11,700 patients (75% under 5 years old), from 33 different sites in 16 countries were followed for 28 days. Loss to follow-up was 4.9% (575/11,700). AS&AQ was given to 5,897 patients. Of these, 82% (4,826/5,897) were included in randomized comparative trials with polymerase chain reaction (PCR) genotyping results and compared to 5,413 patients (half receiving an ACT). AS&AQ and other ACT comparators resulted in rapid clearance of fever and parasitaemia, superior to non-ACT. Using survival analysis on a modified intent-to-treat population, the Day 28 PCR-adjusted efficacy of AS&AQ was greater than 90% (the WHO cut-off) in 11/16 countries. In randomized comparative trials (n = 22), the crude efficacy of AS&AQ was 75.9% (95% CI 74.6-77.1) and the PCR-adjusted efficacy was 93.9% (95% CI 93.2-94.5). The risk (weighted by site) of failure PCR-adjusted of AS&AQ was significantly inferior to non-ACT, superior to dihydroartemisinin-piperaquine (DP, in one Ugandan site), and not different from AS+SP or AL (artemether-lumefantrine). The risk of gametocyte appearance and the carriage rate of AS&AQ was only greater in one Ugandan site compared to AL and DP, and lower compared to non-ACT (p = 0.001, for all comparisons). Anaemia recovery was not different than comparator groups, except in one site in Rwanda where the patients in the DP group had a slower recovery.

CONCLUSION

AS&AQ compares well to other treatments and meets the WHO efficacy criteria for use against falciparum malaria in many, but not all, the sub-Saharan African countries where it was studied. Efficacy varies between and within countries. An IPD analysis can inform general and local treatment policies. Ongoing monitoring evaluation is required.

[Interaction between malaria and intestinal helminthiasis in Senegal: influence of the carriage of intestinal parasites on the intensity of the malaria infection]

Co-infection between intestinal parasites and Plasmodium falciparum is very frequent in inter tropical zone. Our study carried out in the North of Senegal (zone of high prevalence of schistosomiasis) aimed at measuring the influence of the carriage of intestinal parasites on the intensity of malaria infection. The Plasmodium falciparum densities were significantly higher during Plasmodium falciparum/Schistosoma mansoni and Plasmodium falciparum/Ascaris lumbricoides co-infection in children under 14 years old. Other intestinal parasites did not seem to have negative influence on the intensity of Plasmodium falciparum infection.

[Epidemiological study on lymphatic filariasis (Wuchereria bancrofti) in Sénégal]

The purpose of this descriptive study conducted in an area endemic for lymphatic filariasis was to update information on the prevalence, clinical aspects, and awareness of this parasitic disease. All consenting inhabitants over 10 years old in three selected sectors were included. An entomological investigation was carried out to estimate the rate of vector infection. Out of a total of 3.359 subjects examined, 57.3% reported familiarity with the disease and provided an accurate description. The prevalence of clinical manifestations, i.e., mainly adenopathy, attributable to the disease was 14.11%. The overall prevalence rate of parasites was 4.7% with significant variations between sectors. The only parasite species found was Wuchereria bancrofti. Parasite load was low with 68.8% of subjects having less than 10 microfilariae per microliter of blood. Data analysis identified the following risk factors: age with 77.2% of microfilariae carriers over the age of 45 years, sex with 61.4% of carriers being female, and duration of residence in endemic area with 80.4% of carriers living in the area for more than 10 years. Differences were statistically significant. Dissection of 511 female culicidae showed no microfilariae carriers. These data indicate a declining ten-dency in this endemic zone in Senegal.

Efficacy and tolerability of four antimalarial combinations in the treatment of uncomplicated Plasmodium falciparum malaria in Senegal

BACKGROUND

In view of the high level of chloroquine resistance in many countries, WHO has recommended the use of combination therapy with artemisinin derivatives in the treatment of uncomplicated malaria due to Plasmodium falciparum. Four antimalarial drug combinations, artesunate plus amodiaquine (Arsucam), artesunate plus mefloquine (Artequin), artemether plus lumefantrine (Coartem; four doses and six doses), and amodiaquine plus sulphadoxine-pyrimethamine, were studied in five health districts in Senegal.

METHODS

This is a descriptive, analytical, open, randomized study to evaluate the efficacy and tolerability of these four antimalarial combinations in the treatment of uncomplicated falciparum malaria using the 2002 WHO protocol.

RESULTS

All drug combinations demonstrated good efficacy. On day 28, all combinations resulted in an excellent clinical and parasitological response rate of 100% after correction for PCR results, except for the four-dose artemether-lumefantrine regimen (96.4%). Follow-up of approximately 10% of each treatment group on day 42 demonstrated an efficacy of 100%.The combinations were well tolerated clinically and biologically. No unexpected side-effect was observed and all side-effects disappeared at the end of treatment. No serious side-effect requiring premature termination of treatment was observed.

CONCLUSION

The four combinations are effective and well-tolerated.

[Evaluation of serological tests of toxoplasmosis in pregnant women realized at the Laboratory of Parasitology and Mycology of Le Dantec Teaching Hospital in 2002]

INTRODUCTION

the toxoplasmosis can occur complications during pregnancy as serious repercussions on the foetus with the risks linked to this pathology such as abortion. However these complications can be avoided during the pregnancy by an early diagnosis. The objective of this study is to determine the prevalence of toxoplasmosis during pregnancy.

MATERIALS AND METHODS

we undertook this study on 109 pregnant women addressed to the laboratory of parasitology and mycology of the CHU Dantec for toxoplasmosis serological test on 2002. We used a immunoenzymatic technical in solid phase whose principle rests on the change of coloration in the presence of antibody of IgM or IgG; coloration whose intensity is function of the title of antibody. For that, two serological tests (S1 and S2), starting from two venous blood at 3 weeks of interval, are carried out among these pregnant women. This second serology will make it possible to confirm or cancel an evolutionary toxoplasmosis based on the variation of the title in antibody between the first (S1) and the second serology (S2). A control is carried out among these women among whom the diagnosis of the evolutionary toxoplasmosis was established.

RESULTS

they show that with the first (S1), from the 109 patients, 3% were positive with the antibodies IgM type, 22% positive with IgG, and 11% positive with IgG and IgM. 36% of the women present a positive diagnostic at the first serology (S1). The second serology (S2) shows that among the 36% of the women diagnosed positive with the first serology, 11% made an evolutionary toxoplasmosis.

CONCLUSION

This study shows a rather significant of serological toxoplasmosis discovered fortuitously among pregnant women at the time of their assessment of pregnancy.

Childhood mortality and probable causes of death using verbal autopsy in Niakhar, Senegal, 1989-2000

BACKGROUND

In African rural settings, medically certified information on causes of death is largely lacking. The authors applied the verbal autopsy to identify causes of death before 15 years old in a rural area of Senegal where a demographic surveillance system is operating.

METHODS

Between 1989 and 2000, a postmortem interview was conducted using a standardized questionnaire which was independently reviewed by two physicians who assigned the probable underlying cause of death. Discordant diagnoses were discussed by a panel of physicians. Causes of death were grouped into a few categories; cause-specific mortality rates and fractions were generated.

RESULTS

Between 1989 and 1997, all-cause mortality fluctuated. Diarrhoeal diseases, malaria and acute respiratory infections explained between 30% and 70% of the mortality before 10 years of age. In children 1-9 years old, malaria death rate increased between 1989 and 1994 and thereafter did not change. The 1998-2000 years were marked by a peak in mortality, attributed to a meningitis outbreak in children more than one year old paralleled by an increase in death rate from fever of unknown origin, diarrhoeal diseases, and acute respiratory infections in children under 5 years.

CONCLUSIONS

Verbal autopsy provided useful information on the mortality structure responsible for the 1998-2000 peak in mortality. It underlined that, outside outbreak situations, malaria was a leading cause of death for 1-9 year old children and that diarrhoea, acute respiratory infections, or fever from unknown origin accounted for up to 50% of the deaths among the children under 5 years.

[Placental infection by Plasmodium falciparum in an urban area of Senegal]

OBJECTIVES

This study aimed at describing the burden of malaria at delivery in a urban maternity in Senegal. We measured the prevalence of placental malaria infection. We described the association between placental malaria and low birth weight and the impact of chemoprophylaxis.

STUDY AREA

Guediawaye is the most important suburb of the city of Dakar, Senegal, surrounded by a permanent marsh (niayes). Malaria in this area is hypo endemic transmission: 1 infective bite/person/year. An. arabiensis is the principal vector and P. falciparum (98%) the most frequent species. The Maternité Roi Baudoin in Guediawaye is the gynecologic and obstetrical reference centre of this area with more than 6000 deliveries/year.

METHODS

We carried out an exhaustive survey from August 98 to December 99 at the maternité Roi Baudoin in Guediawaye. The socio-demographic data, the clinical data and information about prophylaxy were collected by questionnary. For each woman at delivery, one placental apposition was carried out. Presence of trophozoïtes or schizontes indicated malaria placental infection.

RESULTS

8310 women were included in the study. They were from 13 to 49 years old with an average age of 26.1; 28% were primigravidae. The prevalence of placental malaria infection was 8.1% (674/8310) [Ic95: 7.4-8.8%]. Schizontes were present in 80.5% of infected placenta. The prevalence was 8.8% within primigravidae group and 7.4% in the other parity groups, p = 0.28 (NS). Placental infection was present all the year long. However, there were important seasonal variations. The risk of placental infection increased during seasonal transmission (> 10%) compared to the period of low transmission (3%). The prevalence of placental malaria was lower in the group of women who declares regular chloroquine intake compared with those who declared taking no prophylaxy or irregular prophylaxy (RR = 0.78 [0.62-0.98]). The risk of low birth weight was of 1.9 [1.6-2.1] when the placenta was infected compared with non infected placenta.

CONCLUSION

This study indicates that placental malaria infection is frequent in this low transmission area where more than 70% of women declared taking regular chloroquine. This observation could be explained by a resistance of P. falciparum to chloroquine or a poor observance of chemoprophylaxis.

Hidden Plasmodium falciparum parasites in human infections: different genotype distribution in the peripheral circulation and in the placenta

Sequestration of the mature Plasmodium falciparum forms complicates detection, quantification and molecular analysis of human infections. Whether the circulating parasites represent all or only a subset of co-infecting genotypes is unclear. We have investigated this issue and compared placenta and peripheral blood msp1 and msp2 genotypes in 58 women delivering with an ICT-positive placenta in Guediawaye, Senegal. Most placenta (91%) and blood samples (98%) were multiply infected. Multiplicity of infection was positively correlated in both tissues. However, the placental and circulating genotype profiles differed markedly. Only 10% of matched peripheral blood/placenta samples had identical genotypes, whereas 74% had only partially concordant genotypes, with some alleles detected in both tissues, together with additional allele(s) detected in one tissue only. Eight women (14%) had totally discordant placental and peripheral blood genotypes. Thus, in the vast majority of cases, some sequestered genotypes remain hidden, undetected in the peripheral circulation, indicating that analysis of peripheral parasites generates a partial picture of a P. falciparum infection.