Prevalence of Plasmodium falciparum infection in pregnant women in Gabon

BACKGROUND: In areas where malaria is endemic, pregnancy is associated with increased susceptibility to malaria. It is generally agreed that this risk ends with delivery and decreases with the number of pregnancies. Our study aimed to demonstrate relationships between malarial parasitaemia and age, gravidity and anaemia in pregnant women in Libreville, the capital city of Gabon. METHODS: Peripheral blood was collected from 311 primigravidae and women in their second pregnancy. Thick blood smears were checked, as were the results of haemoglobin electrophoresis. We also looked for the presence of anaemia, fever, and checked whether the volunteers had had chemoprophylaxis. The study was performed in Gabon where malaria transmission is intense and perennial. RESULTS: A total of 177 women (57%) had microscopic parasitaemia; 139 (64%)of them were primigravidae, 38 (40%) in their second pregnancy and 180 (64%) were teenagers. The parasites densities were also higher in primigravidae and teenagers. The prevalence of anaemia was 71% and was associated with microscopic Plasmodium falciparum parasitaemia: women with moderate or severe anaemia had higher parasite prevalences and densities. However, the sickle cell trait, fever and the use of chemoprophylaxis did not have a significant association with the presence of P. falciparum. CONCLUSIONS: These results suggest that the prevalence of malaria and the prevalence of anaemia, whether associated with malaria or not, are higher in pregnant women in Gabon. Primigravidae and young pregnant women are the most susceptible to infection. It is, therefore, urgent to design an effective regimen of malaria prophylaxis for this high risk population

Streptococcus agalactiae Serotype Distribution and Antimicrobial Susceptibility in Pregnant Women in Gabon, Central Africa

Neonatal invasive disease due to Streptococcus agalactiae is life threatening and preventive strategies suitable for resource limited settings are urgently needed. Protective coverage of vaccine candidates based on capsular epitopes will relate to local epidemiology of S. agalactiae serotypes and successful management of critical infections depends on timely therapy with effective antibiotics. This is the first report on serotype distribution and antimicrobial susceptibility of S. agalactiae in pregnant women from a Central African region. Serotypes V, III, and Ib accounted for 88/109 (81%) serotypes and all isolates were susceptible to penicillin and clindamycin while 13% showed intermediate susceptibility to erythromycin

Loa loa Infection in Pregnant Women, Gabon

Loa loa, the African eye worm, is a filarial pathogen of Central African rainforest regions. As of 2013, it had affected an estimated 2–3 million persons in Central Africa (1,2). Adult worm migrations in humans may intermittently cause Calabar swelling, and microfilariae are commonly found in blood and body fluids. Loiasis is a chronic infection persisting for many years; a considerable proportion of women in loiasis-endemic regions are infected during gestation. To date, the epidemiology of loiasis in pregnant women has not been investigated, and the effects of loiasis on maternal and fetal health outcomes are unknown. We investigated the epidemiology of loiasis in a cohort of pregnant women participating in a drug trial for preventing malaria during pregnancy

Young adolescent girls are at high risk for adverse pregnancy outcomes in sub-Saharan Africa: an observational multicountry study

Objectives: One of Africa's most important challenges is to improve maternal and neonatal health. The identification of groups at highest risk for adverse pregnancy outcomes is important for developing and implementing targeted prevention programmes. This study assessed whether young adolescent girls constitute a group at increased risk for adverse birth outcomes among pregnant women in sub-Saharan Africa. Setting: Data were collected prospectively as part of a large randomised controlled clinical trial evaluating intermittent preventive treatment of malaria in pregnancy (NCT00811421—Clinical Trials.gov), conducted between September 2009 and December 2013 in Benin, Gabon, Mozambique and Tanzania. Participants: Of 4749 participants, pregnancy outcomes were collected for 4388 deliveries with 4183 live births including 83 multiple gestations. Of 4100 mothers with a singleton live birth delivery, 24% (975/4100) were adolescents (≤19 years of age) and 6% (248/4100) were aged ≤16 years. Primary and secondary outcome measures: Primary outcomes of this predefined analysis were preterm delivery and low birth weight. Results: The overall prevalence of low birthweight infants and preterm delivery was 10% (371/3851) and 4% (159/3862), respectively. Mothers aged ≤16 years showed higher risk for the delivery of a low birthweight infant (OR: 1.96; 95% CI 1.35 to 2.83). Similarly, preterm delivery was associated with young maternal age (≤16 years; OR: 2.62; 95% CI 1.59 to 4.30). In a subanalysis restricted to primiparous women: preterm delivery, OR 4.28; 95% CI 2.05 to 8.93; low birth weight, OR: 1.29; 95% CI 0.82 to 2.01. Conclusions: Young maternal age increases the risk for adverse pregnancy outcomes and it is a stronger predictor for low birth weight and preterm delivery than other established risk factors in sub-Saharan Africa. This finding highlights the need to improve adolescent reproductive health in sub-Saharan Africa

Effects of Plasmodium falciparum Parasite Population Size and Patient Age on Early and Late Parasitological Outcomes of Antimalarial Treatment in Children▿

The design and interpretation of trials assessing the chemotherapeutic effects of antimalarial drugs depend on our understanding of how different selection criteria affect treatment outcomes. In this study, we analyzed the effects of baseline parameters on the initial parasite elimination rate and the risk of subsequent recrudescence as a marker for incompletely eliminated asexual blood-stage parasites in pediatric patients with uncomplicated Plasmodium falciparum infection treated with amodiaquine in a high-transmission area. We found that (i) parasite population size and patient age independently determine early and late parasitological treatment outcome measurements; (ii) the rate of recrudescence is higher in patients 1 to 3 years of age than in patients aged <1 or >3 years; (iii) patients aged >5 years with parasite densities between 2,000 and 10,000/μl have a lower recrudescence rate (13%; 95% confidence interval [CI], 8% to 21%) than patients aged <5 years with parasite densities of >10,000/μl (40%; 95% CI, 30% to 50%); and (iv) the sensitivity of detecting recrudescences outside this high-risk group, i.e., in patients of >5 years of age or with parasite densities of <10,000/μl, is as low as 27% or 22%, respectively. In conclusion, these findings highlight the need to use adequate selection criteria and to report parasitological outcome results adjusted for the readily available determinants of chemotherapeutic failure, i.e., patient age and baseline parasitemia. The thresholds may vary by transmission intensity and drug regimen. A better understanding of the limitations of antimalarial regimens in high-risk subgroups of patients has important implications for setting policy recommendations

High prevalence of genotypes associated with sulfadoxine/pyrimethamine resistance in the rural area of Fougamou, Gabon

ABSTRACT: Objectives: Pregnancy-associated malaria (PAM) is a complex form of malaria. To prevent PAM, several African countries have adopted intermittent preventive treatment with sulfadoxine/pyrimethamine (IPT-SP). However, resistance to SP has been reported, associated with mutations in the genes Plasmodium falciparum dihydropteroate synthase (Pfdhps) and P. falciparum dihydrofolate reductase (Pfdhfr). The aim of this study was to investigate the prevalence of mutations in Pfdhfr and Pfdhps in P. falciparum isolates from rural areas of Gabon. Methods: A cross-sectional survey of febrile patients (n = 202) who consulted Fougamou Health Center between February–May 2016 was performed. DNA was extracted from patient samples and the Pfdhfr and Pfdhps genes were genotyped using PCR-RFLP. Statistical analyses were performed. Results: The malaria prevalence in febrile patients included in the study was 60.4% (122/202). The main parasite species was P. falciparum (96.7%; 118/122), followed by Plasmodium malariae (3.3%; 4/122). Genotypes on codons 16, 51, 59 and 108 of Pfdhfr were highly mutated (>96%). In Pfdhps, codons 436, 437, 540 and 613 also expressed high mutation rates. The prevalence of triple mutations of Pfdhfr VIRNI and AIRNI was 12.1% and 84.5%, respectively. The prevalence of mutant haplotypes of Pfdhps SGEA, SGKA and AGEA was 37.9%, 25.9% and 12.1%, respectively. The prevalence of quadruple mutants IRN-A and IRN-G was 20.0% and 93.1%, respectively, whereas quintuple mutants were found at 57.8% (IRN-GE) and 5.0% (IRN-AE). Conclusion: Our data show a high prevalence of genotypes associated with SP resistance. Clinical trials to investigate the efficacy of IPT-SP are much needed

Short-Course Artesunate Treatment of Uncomplicated Plasmodium falciparum Malaria in Gabon

Artesunate is one of the most important antimalarial agents available, since it is effective against parasites that have developed resistance to conventional antimalarials in sub-Saharan Africa. Antimalarial combination chemotherapies with artesunate (4 mg/kg of body weight once daily for 3 days) as one partner have been proposed. However, the efficacy of a 3-day course of artesunate alone has never been evaluated in individuals in Africa (which has 90% of the worldwide malaria burden) living in regions of hyperendemicity, where a considerable degree of immunity might substantially enhance the efficacy of short courses of artesunate compared to those in regions where the levels of endemicity are low. This lack of information does not permit a systematic assessment of the value of artesunate-based combination chemotherapies in Africa. Therefore, we studied the efficacy and safety of a 3-day course of artesunate (4 mg/kg of body weight, orally, once daily) for the treatment of uncomplicated Plasmodium falciparum malaria in Gabonese patients aged 4 to 15 years (n = 50). Artesunate was well tolerated, and no severe adverse event was reported. Parasite elimination was rapid and was achieved in all patients within ≤72 h (geometric mean time to elimination, 34 h). The PCR-corrected cure rate by day 14 was 92% (46 of 50 patients), but it dropped to 72% (36 of 50 patients) by day 28. We conclude that a 3-day course of artesunate fails to achieve sufficiently high cure rates for uncomplicated falciparum malaria in Gabonese children