Publications by authors named "Peter Ouma"

In areas of moderate to intense Plasmodium falciparum transmission, malaria in pregnancy remains a significant cause of low birth weight, stillbirth, and severe anaemia. Previously, fetal sex has been identified to modify the risks of maternal asthma, pre-eclampsia, and gestational diabetes. One study demonstrated increased risk of placental malaria in women carrying a female fetus.

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Background: Malaria is among the top causes of death in adolescent girls (10 to 19 years) globally. Adolescent motherhood is associated with increased risk of adverse maternal and neonatal outcomes. The interaction of malaria, adolescence, and pregnancy is especially relevant in malaria endemic areas, where rates of adolescent pregnancy are high.

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Background: In malaria endemic regions in Kenya, pregnant women are offered long-lasting insecticidal nets and intermittent preventive treatment (IPTp) with sulfadoxine-pyrimethamine (SP) at antenatal care (ANC) to prevent the adverse effects of malaria. Fears of growing SP resistance have heightened the search for alternative strategies. The implementation feasibility of intermittent screening and treatment (ISTp) with dihydroartemisinin-piperaquine (DP) in routine ANC settings was evaluated using qualitative and quantitative methods, including the exploration of healthcare provider and pregnant women's perceptions.

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Dihydroartemisinin-piperaquine (DP) is a long-acting artemisinin combination treatment that provides effective chemoprevention and has been proposed as an alternative antimalarial drug for intermittent preventive therapy in pregnancy (IPTp). Several pharmacokinetic studies have shown that dose adjustment may not be needed for the treatment of malaria in pregnancy with DP. However, there are limited data on the optimal dosing for IPTp.

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Background: Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is recommended for preventing malaria in pregnancy in areas of moderate-to-high transmission in sub-Saharan Africa. However, due to increasing parasite resistance to SP, research on alternative strategies is a priority. The study assessed the implementation feasibility of intermittent screening and treatment (ISTp) in the second and third trimester at antenatal care (ANC) with malaria rapid diagnostic tests (RDTs) and treatment of positive cases with dihydroartemisinin-piperaquine (DP) compared to IPTp-SP in western Kenya.

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Background: While there is increasing evidence on the safety of artemisinin-based combination therapy (ACT) for the case management of malaria in early pregnancy, little is known about the association between exposure to ACT during the first trimester and the effect on fetal growth.

Methods: Data were analysed from prospective studies of pregnant women enrolled in Mozambique, Burkina Faso and Kenya designed to determine the association between anti-malarial drug exposure in the first trimester and pregnancy outcomes, including low birth weight (LBW) and small for gestational age (SGA). Exposure to anti-malarial drugs was ascertained retrospectively by record linkage using a combination of data collected from antenatal and adult outpatient clinic registries, prescription records and self-reported medication usage by the women.

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Pregnant women constitute a promising sentinel group for continuous monitoring of malaria transmission. To identify antibody signatures of recent Plasmodium falciparum exposure during pregnancy, we dissected IgG responses against VAR2CSA, the parasite antigen that mediates placental sequestration. We used a multiplex peptide-based suspension array in 2,354 samples from pregnant women from Mozambique, Benin, Kenya, Gabon, Tanzania, and Spain.

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Prompt diagnosis and effective treatment of acute malaria in pregnancy (MiP) is important for the mother and fetus; data on health-care provider adherence to diagnostic guidelines in pregnancy are limited. From September to November 2013, a cross-sectional survey was conducted in 51 health facilities and 39 drug outlets in Western Kenya. Provider knowledge of national diagnostic guidelines for uncomplicated MiP were assessed using standardized questionnaires.

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Background: Four studies previously indicated that the effect of malaria infection during pregnancy on the risk of low birthweight (LBW; <2,500 g) may depend upon maternal nutritional status. We investigated this dependence further using a large, diverse study population.

Methods And Findings: We evaluated the interaction between maternal malaria infection and maternal anthropometric status on the risk of LBW using pooled data from 14,633 pregnancies from 13 studies (6 cohort studies and 7 randomized controlled trials) conducted in Africa and the Western Pacific from 1996-2015.

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Background: Resistance and tolerance to Plasmodium falciparum can determine the progression of malaria disease. However, quantitative evidence of tolerance is still limited. We investigated variations in the adverse impact of P.

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Background: Animal embryotoxicity data, and the scarcity of safety data in human pregnancies, have prevented artemisinin derivatives from being recommended for malaria treatment in the first trimester except in lifesaving circumstances. We conducted a meta-analysis of prospective observational studies comparing the risk of miscarriage, stillbirth, and major congenital anomaly (primary outcomes) among first-trimester pregnancies treated with artemisinin derivatives versus quinine or no antimalarial treatment.

Methods And Findings: Electronic databases including Medline, Embase, and Malaria in Pregnancy Library were searched, and investigators contacted.

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Purpose: The Maternal Malaria and Malnutrition (M3) initiative has pooled together 13 studies with the hope of improving understanding of malaria-nutrition interactions during pregnancy and to foster collaboration between nutritionists and malariologists.

Participants: Data were pooled on 14 635 singleton, live birth pregnancies from women who had participated in 1 of 13 pregnancy studies. The 13 studies cover 8 countries in Africa and Papua New Guinea in the Western Pacific conducted from 1996 to 2015.

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Introduction: Historically, Kenya has used various distribution models for long-lasting insecticide-treated bed nets (LLINs) with variable results in population coverage. The models presently vary widely in scale, target population and strategy. There is limited information to determine the best combination of distribution models, which will lead to sustained high coverage and are operationally efficient and cost-effective.

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Background: Although anti-malarial medicines are free in Kenyan public health facilities, patients often seek treatment from private sector retail drug outlets. In mid-2010, the Affordable Medicines Facility-malaria (AMFm) was introduced to make quality-assured artemisinin-based combination therapy (ACT) accessible and affordable in private and public sectors.

Methods: Private sector retail drug outlets stocking anti-malarial medications within a surveillance area of approximately 220,000 people in a malaria perennial high-transmission area in rural western Kenya were identified via a census in September 2013.

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Background: Coverage with malaria in pregnancy interventions remains unacceptably low. Implementation research is needed to identify and quantify the bottlenecks for the delivery and use of these life-saving interventions through antenatal clinics (ANC).

Methods: A cross-sectional study was carried out in ANC across nine health facilities in western Kenya.

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Objective: Information on adverse pregnancy outcomes is important to monitor the impact of public health interventions. Miscarriage is a challenging end point to ascertain and there is scarce information on its rate in low-income countries. The objective was to estimate the background rate and cumulative probability of miscarriage in rural western Kenya.

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Background: The World Health Organization recommends intermittent preventive treatment in pregnancy (IPTp) with sulphadoxine-pyrimethamine (SP) alongside long-lasting insecticide-treated nets (LLIN) and case management for reducing the risks associated with malaria in pregnancy in areas of moderate-to-high transmission in sub-Saharan Africa. Due to increasing Plasmodium falciparum resistance to SP, the search for alternative drugs or strategies to control malaria in pregnancy is a priority. We assessed the acceptability among pregnant women and health providers of intermittent screening and treatment (ISTp) and IPTp with dihydroartemisinin-piperaquine (DP) as alternative strategies in the context of an un-blinded clinical trial.

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Background: Intermittent mass screening and treatment (iMSaT) is currently being evaluated as a possible additional tool for malaria control and prevention in western Kenya. The literature identifying success and/or barriers to drug trial compliance and acceptability on malaria treatment and control interventions is considerable, especially as it relates to specific target groups, such as school-aged children and pregnant women, but there is a lack of such studies for mass screening and treatment and mass drug administration in the general population.

Methods: A qualitative study was conducted to explore community perceptions of the iMSaT intervention, and specifically of testing and treatment in the absence of symptoms, before and after implementation in order to identify aspects of iMSaT that should be improved in future rounds.

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Background: Although prompt, effective treatment is a cornerstone of malaria control, information on provider adherence to malaria in pregnancy (MIP) treatment guidelines is limited. Incorrect or sub-optimal treatment can adversely affect the mother and fetus. This study assessed provider knowledge of and adherence to national case management guidelines for uncomplicated MIP.

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Background: Intermittent preventive treatment in pregnancy with sulfadoxine/pyrimethamine is contra-indicated in HIV-positive pregnant women receiving sulfamethoxazole/trimethoprim prophylaxis. Since mefloquine is being considered as a replacement for sulfadoxine/pyrimethamine in this vulnerable population, an investigation on the pharmacokinetic interactions of mefloquine, sulfamethoxazole and trimethoprim in pregnant, HIV-infected women was performed.

Methods: A double-blinded, placebo-controlled study was conducted with 124 HIV-infected, pregnant women on a standard regimen of sulfamethoxazole/trimethoprim prophylaxis.

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Background: A major unresolved safety concern for malaria case management is the use of artemisinin combination therapies (ACTs) in the first trimester of pregnancy. There is a need for human data to inform policy makers and treatment guidelines on the safety of artemisinin combination therapies (ACT) when used during early pregnancy.

Methods: The overall goal of this paper is to describe the methods and implementation of a study aimed at developing surveillance systems for identifying exposures to antimalarials during early pregnancy and for monitoring pregnancy outcomes using health and demographic surveillance platforms.

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Background: The artemisinin anti-malarials are widely deployed as artemisinin-based combination therapy (ACT). However, they are not recommended for uncomplicated malaria during the first trimester because safety data from humans are scarce.

Methods: This was a prospective cohort study of women of child-bearing age carried out in 2011-2013, evaluating the relationship between inadvertent ACT exposure during first trimester and miscarriage.

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Background: Owing to increasing sulfadoxine-pyrimethamine (SP) resistance in sub-Saharan Africa, monitoring the effectiveness of intermittent preventive therapy in pregnancy (IPTp) with SP is crucial.

Methods: Between 2009 and 2013, both the efficacy of IPTp-SP at clearing existing peripheral malaria infections and the effectiveness of IPTp-SP at reducing low birth weight (LBW) were assessed among human immunodeficiency virus-uninfected participants in 8 sites in 6 countries. Sites were classified as high, medium, or low resistance after measuring parasite mutations conferring SP resistance.

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Background: Every year, more than 32 million pregnancies in sub-Saharan Africa are at risk of malaria infection and its adverse consequences. The effectiveness of the intermittent preventive treatment with sulfadoxine-pyrimethamine strategy recommended by WHO is threatened by high levels of parasite resistance. We aimed to assess the efficacy and safety of two alternative strategies: intermittent screening with malaria rapid diagnostic tests and treatment of women who test positive with dihydroartemisinin-piperaquine, and intermittent preventive treatment with dihydroartemisinin-piperaquine.

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Background: In western Kenya, maternal mortality is a major public health problem estimated at 730/100,000 live births, higher than the Kenyan national average of 488/100,000 women. Many women do not attend antenatal care (ANC) in the first trimester, half do not receive 4 ANC visits. A high proportion use traditional birth attendants (TBA) for delivery and 1 in five deliver unassisted.

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