Charles O Obonyo

Kenya Medical Research Institute | KEMRI · Centre for Global Health Research

Background Reliance on praziquantel for the treatment and control of schistosomiasis is likely to facilitate the emergence of drug resistance. Combination therapy targeting adult and juvenile schistosome worms is urgently needed to improve praziquantel efficacy and delay the potential development of drug resistance. We assessed the efficacy and saf...

Unlike praziquantel, artemisinin derivatives are effective against juvenile schistosome worms. We assessed the efficacy and safety of a single oral dose of artesunate plus sulfalene-pyrimethamine versus praziquantel in the treatment of Schistosoma mansoni. Seventy-three schoolchildren (aged 9–15 years) with confirmed S. mansoni infection in Rarieda...

Background Reliance on praziquantel for treatment and control of schistosomiasis is likely to facilitate the emergence of drug resistance. Combination therapy targeting adult and juvenile schistosome worms is urgently needed to improve praziquantel efficacy and delay the development of drug resistance. We assessed the efficacy and safety of single-...

Background Praziquantel alone is insufficient for the control of schistosomiasis. Unlike praziquantel, artemisinin derivatives are effective for treating juvenile schistosome worms but not adult worms. Few studies have assessed the role of combination therapy, including praziquantel and artemisinin-based combinations, in treating schistosomiasis....

Background Schistosomiasis control relies on praziquantel for preventive chemotherapy. Alternative drugs are needed for the treatment and control of schistosomiasis. Praziquantel is effective against adult schistosome worms but ineffective against larval stages of the parasite and cannot prevent re-infection or interrupt the transmission of infecti...

Background: Schistosomiasis control relies on praziquantel for preventive chemotherapy. Alternative drugs are needed for the treatment and control of schistosomiasis. Praziquantel is effective against adult schistosome worms but ineffective against larval stages of the parasite and cannot prevent re-infection or interrupt the transmission of infec...

Understanding urban travel behaviour is crucial for planning healthy and sustainable cities. Africa is urbanising at one of the fastest rates in the world and urgently needs this knowledge. However, the data and literature on urban travel behaviour, their correlates, and their variation across African cities are limited. We aimed to describe and co...

Introduction Socioeconomic inequalities contribute to poor health. Inequitable access to diverse and healthy foods can be a risk factor for non-communicable diseases, especially in individuals of low socioeconomic status. We examined the extent of socioeconomic inequalities in food purchasing practices, expenditure, and consumption in a resource-po...

Introduction Rapid urbanization (growth of cities) can upset the local population's health and wellbeing by creating obesogenic environments which increase the burden of non-communicable diseases (NCDs). It is important to understand how stakeholders perceive the impact of urbanizing interventions (such as the construction of a new hypermarket) on...

The literature on urban travel behaviour in Africa is sparse, limiting our understanding of how urban transport policies respond to human and planetary needs. We conducted a cross-sectional household telephone survey on 1334 participants, using a 24 h time-use diary, to investigate travel behaviour and barriers to active travel (walking and cycling...

Introduction Non-communicable diseases have risen markedly over the last decade. A phenomenon that was mainly endemic in high-income countries has now visibly encroached on low and middle-income settings. A major contributor to this is a shift towards unhealthy dietary behavior. This study aimed to examine the complex interplay between people’s cha...

Schistosomiasis is a helminthiasis infecting approximately 250 million people worldwide. In 2001, the World Health Assembly (WHA) 54.19 resolution defined a new global strategy for control of schistosomiasis through preventive chemotherapy programmes. This resolution culminated in the 2006 WHO guidelines that recommended empirical treatment by mass...

Introduction Low household socioeconomic status is associated with unhealthy behaviours including poor diet and adverse health outcomes. Different methods leading to variations in SES classification has the potential to generate spurious research findings or misinform policy. In low and middle-income countries, there are additional complexities in...

Background The World Health Organization recommends quinine plus clindamycin as first-line treatment of malaria in the first trimester of pregnancy and as a second-line treatment for uncomplicated falciparum malaria when artemisinin-based drug combinations are not available. The efficacy of quinine plus clindamycin was compared with that of artemet...

Introduction Low household socioeconomic status is associated with unhealthy behaviours including poor diet and adverse health outcomes. Different methods leading to variations in SES classification has the potential to generate spurious research findings or misinform policy. In low and middle-income countries, there are additional complexities in...

The triple burden of malnutrition in many low- and middle-income countries (LMICs) is partly a result of changing food environments and a shift from traditional diets to high-calorie Western-style diets. Exploring the relationship between food sources and food- and nutrition-related outcomes is important to understanding how changes in food environ...

Background: World Health Organisation recommends quinine plus clindamycin as first-line treatment of malaria in the first trimester of pregnancy and as a second-line treatment for uncomplicated falciparum malaria when artemisinin-based drug combinations are not available. We compared the efficacy of quinine plus clindamycin with that of artemether-...

Aflatoxins are naturally occurring carcinogenic toxins associated with poor growth outcomes in young children. Although evidence supports mother-to-infant exposure during pregnancy and breastfeeding, evidence of its effect on growth is limited to the period after introduction of complementary foods. It is, therefore, unclear whether early maternal...

IntroductionThe nutritional transition is fuelling a concerning rise in Non-Communicable Diseases (NCDs) in Low and Middle-Income Countries (LMICs). These countries lack strong health infrastructure capable of supporting the long-term and expensive medical treatment for those living with NCDs. It is important to identify stakeholders involved in in...

Introduction: Non-communicable diseases have risen markedly over the last decade. A phenomenon that was mainly endemic in high income countries has now visibly encroached in low and middle-income settings. A major contributor to this is a shift towards unhealthy dietary behavior. The aim of this study was to examine the complex interplay between in...

At the time of writing, it is unclear how the COVID-19 pandemic will play out in rapidly urbanising regions of the world. In these regions, the realities of large overcrowded informal settlements, a high burden of infectious and non-communicable diseases, as well as malnutrition and precarity of livelihoods, have raised added concerns about the pot...

BACKGROUND The increasing burden of non-communicable diseases (NCDs), which are prevalent in low and middle income countries (LMICs), is largely attributed to modifiable behavioural risk factors such as poor/unhealthy diets and insufficient physical activity (PA). The adolescent stage–recently defined as 10-24 years of age–is an important formative...

Background The increasing burden of noncommunicable diseases that are prevalent in low- and middle-income countries (LMICs) is largely attributed to modifiable behavioral risk factors such as unhealthy diets and insufficient physical activity (PA). The adolescent stage, defined as 10 to 24 years of age, is an important formative phase of life and o...

Background Non-communicable diseases (NCDs) are the leading cause of death globally. While upstream approaches to tackle NCD risk factors of poor quality diets and physical inactivity have been trialled in high income countries (HICs), there is little evidence from low and middle-income countries (LMICs) that bear a disproportionate NCD burden. Sub...

Background: The global control strategy for schistosomiasis is the periodic administration of praziquantel. Schistosomes have developed reduced susceptibility to praziquantel. Artemisinin-based drug combinations are promising alternatives to praziquantel, but it is unclear whether a single dose of an artemisinin-based drug combination is as effecti...

BACKGROUND Access to healthy food is considered a key determinant of dietary behaviour and there is mixed evidence that living near a supermarket is associated with a healthier diet. In Africa, supermarkets may contribute to the nutrition transition by offering both healthy and unhealthy foods; and by replacing traditional food sellers. In Kisumu,...

Background Access to healthy food is considered a key determinant of dietary behavior, and there is mixed evidence that living near a supermarket is associated with a healthier diet. In Africa, supermarkets may contribute to the nutrition transition by offering both healthy and unhealthy foods and by replacing traditional food sellers. In Kisumu, K...

Rationale: Obstructive sleep apnea (OSA) is a significant health problem of adults and children globally, resulting in decreased quality of life and increased health care utilization costs. For optimal clinical care, primary care physicians should be familiar and confident in their abilities to screen, diagnose and manage OSA. Objective: To asse...

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To compare the effects of praziquantel given twice a year, with annual or biennial regimens on the prevalence and intensity of schistosomiasis infection. © 2019 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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 deve...

Malaria is a leading cause of morbidity and mortality in Kenya, mostly affecting the rural poor, especially young children and pregnant women. Most clinical studies in malaria involve a number of equally important endpoints. This would normally portend challenges in relation to issues about the study design, analysis of the data and interpretation...

Kenya is intensifying its national efforts in malaria control to achieve malaria elimination. Detailed characterization of malaria infection among populations living in the areas where the disease is endemic in Kenya is a crucial priority, especially for planning and evaluating future malaria elimination strategy. This study aimed to investigate th...

Recent changes to Kenya's early infant diagnosis (EID) testing algorithm have raised hope that the national goal of reducing perinatal HIV transmission rates to less than 5% can be attained. While programmatic efforts to reach this target are underway, obtaining complete and accurate data from clinical sites to track progress presents a major chall...

Objective To assess prevalence and occupational risk factors of latent TB infection and history of TB disease ascribed to work in a health care setting in western Kenya.Methods We conducted a cross-sectional survey among health care workers in western Kenya in 2013. They were recruited from dispensaries, health centers, and hospitals that offer bot...

About 4.5 billion people globally and 1.8 million Kenyans are exposed to large amount of aflatoxin. However, little is known about aflatoxin exposure levels in pregnant women through dietary intake. This study aimed to determine levels of aflatoxin exposure of pregnant women in Kisumu County, where up to 40% households have been found to be exposed...

Contamination of foods by aflatoxins is a global health problem in both developed and developing countries. Exposure to the toxin s is associated with a range of effects on health including stunting in children. Commodities at high risk of aflatoxin contamination include cereals, legumes, milk, fish and meats. Children are more vulnerable to effect...

Pharmacokinetic (PK) and pharmacodynamic (PD) data are limited for artesunate (AS) and amodiaquine (AQ) in uncomplicated Plasmodium falciparum. From 2007-8, 54 P. falciparum-infected, Kenyan adults were assigned randomly fixed dose (FD) ASAQ (n=26) or non-fixed (NF) ASAQ (n=28). Total doses were 600 mg AS (both arms) + 1,620 mg (FD) or 1,836 mg (NF...

Abstract: Introduction: A high proportion of the estimated 1.7 million people who die annually in Kenya occur in hospital settings and are laid in a mortuary before burial. Nyanza Province has a high morbidity and mortality rate, due to infectious diseases. Consequently, the mortuary facilities are overstretched and staff manning them may be expose...

This open-label, randomized study evaluated efficacy and safety of artemether-lumefantrine (AL) and dihydroartemisinin-piperaquine (DP) in treatment of uncomplicated falciparum malaria in children below five years of age, to build evidence on use of AL as first-line treatment and DP as second-line treatment in Kenya. A total of 454 children aged si...

Half a million women die annually from pregnancy related causes. In Kenya, maternal mortality ratio (MMR) remains high in spite of great efforts to improve maternal health care. We studied some factors linked to maternity in a rural community setting. A survey was conducted in the community living in Madiany division of Siaya County, Kenya. We rand...

Women Empowerment and Skilled Attendance/Facility Delivery in a Rural Community of Western Kenya Asweto, C. O.1,3, Ouma, J. O.3 Aluoch, J. R.1 , Obonyo, C. O.2 1. School of Public Health and Community Development, Maseno University 2. Kenya Medical Research Institute, Center for Global Health Research (KEMRI) Kisumu. 3. Tropical Institute of Commun...

Artemisinin-based combinations are recommended for treatment of uncomplicated falciparum malaria, but are costly and in limited supply. Clindamycin plus quinine is an alternative non-artemisinin-based combination recommended by World Health Organization. The efficacy and safety of clindamycin plus quinine is not known. This systematic review aims t...

Schistosomiasis is an important parasitic disease in Kenya. Decreasing susceptibility of schistosomes to praziquantel, the major drug used to reduce disease morbidity, has made assessment of new antischistosomal drugs a priority. We aimed to assess the safety and efficacy of an artesunate-based combination drug in the treatment of schistosomiasis....

Amodiaquine (AQ) is an antimalarial drug that was frequently combined with artesunate (AS) for the treatment of uncomplicated malaria due to Plasmodium falciparum and is now available as a fixed-dose combination. Despite its widespread use, the simultaneous pharmacokinetics in patients of AQ and its active metabolite, desethylamodiaquine (DAQ), wer...

Artemether/lumefantrine (AL) has been adopted as the treatment of choice for uncomplicated malaria in Kenya and other countries in the region. Six-dose artemether/lumefantrine tablets are highly effective and safe for the treatment of infants and children weighing between five and 25 kg with uncomplicated Plasmodium falciparum malaria. However, ora...

Short report by the sponsor Dafra Pharma nv/sa. A relative bioavailability study for Fixed Dose Combination (FDC) comparing Coartem Tablets (containing Artemether 20 mg and Lumefantrine 120 mg) of Novartis Pharmaceuticals Limited, EU with Co-Artesiane® dry powder for suspension (containing β-Artemether 360 mg and Lumefantrine 2160 mg in 45.6 g dry...

Discussion Dosing Al. Following the WHO guidelines for the treatment of malaria (WHO, 2006, pages 23–24) the recommended dose for artemether/lumefantrine tablets (Coartem®) when used for children between 5 and 14 kg is 1 tablet at time 0 h and 1 tablet at time 8 h followed by two tablets a day for two days (24, 36, 48 and 60 h). Calculated as mg ar...

Severe malarial anemia (SMA) is a leading cause of pediatric morbidity, hospitalization, and mortality in sub-Saharan Africa, and yet its contribution to malaria-specific mortality is not well documented. We retrospectively reviewed the clinical records of 1,116 children < 5 years of age admitted to Siaya district hospital, western Kenya, to assess...

Malaria-associated anaemia is a major public-health problem. Although the treatment of uncomplicated, Plasmodium falciparum malaria aims to clear the parasites, relieve the symptoms and permit haematological recovery, data on the impact of antimalarial treatment on haematological recovery are few. Haematological recovery and the prevalence of anaem...

Drug resistance in Plasmodium falciparum is a major obstacle to malaria control. Artemisinin-based combination therapy (ACT) is being advocated to improve treatment efficacy and to delay development of resistance. Here we summarise the available data on the efficacy of amodiaquine plus sulfadoxine/pyrimethamine (AQ+SP) versus ACTs in the treatment...

The altered immune response of persons with human immunodeficiency virus (HIV) infection could result in increased rates of antimalarial treatment failure. We investigated the influence of HIV infection on the response to sulfadoxine-pyrimethamine treatment. Febrile adults with Plasmodium falciparum parasitemia were treated with sulfadoxine-pyrimet...

The choice of partner drug is critical for artemisinine-based combination therapy (ACT) to remain effective and amodiaquine (AQ) is one important candidate to evaluate.We treated 81 children <5 years with uncomplicated Plasmodium falciparum malaria with AQ alone and related the treatment outcome to the possible selection of pfcrt 76T, 152T, 163S, 3...

Haemophilus influenzae type b (Hib) infection is a leading cause of meningitis and pneumonia in infants and children in developing countries, and yet the implementation of routine Hib vaccination is very slow. The aim of the present study was to quantify the protective efficacy of H. influenzae type b vaccination of young children. MEDLINE, EMBASE,...

Malaria-associated anaemia is a potentially preventable cause of severe morbidity and mortality in children < 5years of age, in areas of high malaria transmission in sub-Saharan Africa. In a cross-sectional study of 3586 children, 80% were anaemic (haemoglobin [Hb]<11g/dL) and 3% had severe anaemia (Hb<5g/dL). Risk factors for anaemia included age...

Malaria associated severe anemia in children is the most important complication of Plasmodium falciparum infection in sub-Saharan Africa. To evaluate anemia and malaria in an area with recurrent malaria epidemics in the western highlands of Kenya, we conducted cross-sectional surveys in four "lowland" (1440-1660 m) and two "highland" (1960 and 2040...

Background Addition of artemisinin derivatives to existing drug regimens for malaria could reduce treatment failure and transmission potential. We assessed the evidence for this hypothesis from randomised controlled trials. Methods We undertook a meta-analysis of individual patients' data from 16 randomised trials (n=5948) that studied the effects...

Plasmodium falciparum has developed resistance to almost all routinely used antimalarial drugs. Sulfadoxine-pyrimethamine (SP) has replaced chloroquine as first-line treatment of uncomplicated malaria infection in Kenya but resistance to SP is already reported. The addition of artemisinin derivatives to SP may delay the development of drug resistan...

In spite of increasing resistance, chloroquine remains the primary drug for treatment of malaria in most sub-Saharan African countries. We evaluated the effect of drug treatment policy on the case-fatality rates of children, adjusting for differing distributions of malaria and severe anemia. In 1991, 63% of children were treated with chloroquine wh...

Severe childhood malarial anemia is commonly treated using blood transfusion. Although transfusion may decrease short-term mortality, the risk of human immunodeficiency virus (HIV) transmission is considerable in Africa. We constructed a decision tree to weigh the short-term mortality benefit of transfusion against HIV infection risk. Probability e...