Cryptosporidiosis and its genotypes among children attending Moi Teaching and Referral Hospital in Eldoret, Kenya

Objectives: To determine the prevalence of cryptosporidiosis and the associated factors, and characterise the Cryptosporidium isolates from children aged five years and less with diarrhoea.Design: A prospective cross-sectional study.Setting: This was a health facility and laboratory based study. Screening forCryptosporidium oocysts was done at the Microbiology laboratory, School of Medicine, Moi University, Eldoret and genotyping and sub-genotyping at the Kenya Medical Research Institute, Nairobi, Kenya.Subjects: Children aged five years and less seen at the outpatient clinic and those admitted in the pediatric wards at MTRH were recruited into the study upon obtaining assent and written consent from the parents or guardians.Results: The prevalence of cryptosporidiosis was 9.8% (N=317). A duration of diarrhoea of more than two weeks was associated with cryptosporidiosis (OR= 1.8301) compared to those with diarrhoea for less than one week. There were no sex related differences in the cryptosporidiosis prevalence (P= 0.9752). Waste disposal, water sources and treatment, and livestock in homesteads were not associated with cryptosporidiosis. About 82% of the isolates were C. hominis and 18% were C. parvum. There were 6subtypes of C. hominis and 4 subtypes of C. parvum in circulation.Conclusion: The prevalence of cryptosporidiosis is comparable to other regions of the world with C. hominis being the most common followed by C. parvum. Human-to-human transmission is the main mode of spread of cryptosporidiosis. All the Cryptosporidium isolates were from children residing in peri-urban and rural areas

Intestical polyparasitism in a rural Kenyan community

Background: Polyparasitism seems to be a common feature in human populations in sub-Saharan Africa. However, very little is known about its epidemiological significance, its long term impact on human health or the types of interactions that occur between the different parasite species involved.Objectives: To determine the prevalence and co-occurrence of intestinal parasites in a rural community in the Kibwezi, Makueni district, Kenya.Design: A cross sectional study.Setting: Kiteng’ei village, Kibwezi, Makueni district, between May and September 2006.Subjects: One thousand and forty five who comprised of 263 adult males, 271 adult females> 15 years of age and 232 boys, and 279 girls < 15 years of age.Interventions: All infected members of the community were offered Praziquantel (at dosages of 40 mg/ kg body weight) for Schistosomiasis and Albendazole (600 mg) for soil transmitted helminths.Results: A total of ten intestinal parasite species (five protozoan and five helminth parasite species) were present in this community and polyparasitsm was common in individuals 5- 24 years of age with no gendar related differences. Most of the infections were mild. The protozoan parasites of public health significance present were Entamoeba histolytica and Giardia lamblia with prevalence of 12.6% and 4.2%, respectively. The helminth parasites of public health significance in the locality were Schistosoma mansoni with a prevalence of 28%, and hookworms prevalence of 10%. About 53% of the study population harboured intestinal parasite infections, with 31 % of the infected population carrying single parasite species infections, and 22% harbouring two or more intestinal parasite species per individual. Significant positive associations (p value

Quantitative High-Throughput Screen Identifies Inhibitors of the Schistosoma mansoni Redox Cascade

Schistosomiasis is a tropical disease associated with high morbidity and mortality, currently affecting over 200 million people worldwide. Praziquantel is the only drug used to treat the disease, and with its increased use the probability of developing drug resistance has grown significantly. The Schistosoma parasites can survive for up to decades in the human host due in part to a unique set of antioxidant enzymes that continuously degrade the reactive oxygen species produced by the host's innate immune response. Two principal components of this defense system have been recently identified in S. mansoni as thioredoxin/glutathione reductase (TGR) and peroxiredoxin (Prx) and as such these enzymes present attractive new targets for anti-schistosomiasis drug development. Inhibition of TGR/Prx activity was screened in a dual-enzyme format with reducing equivalents being transferred from NADPH to glutathione via a TGR-catalyzed reaction and then to hydrogen peroxide via a Prx-catalyzed step. A fully automated quantitative high-throughput (qHTS) experiment was performed against a collection of 71,028 compounds tested as 7- to 15-point concentration series at 5 µL reaction volume in 1536-well plate format. In order to generate a robust data set and to minimize the effect of compound autofluorescence, apparent reaction rates derived from a kinetic read were utilized instead of end-point measurements. Actives identified from the screen, along with previously untested analogues, were subjected to confirmatory experiments using the screening assay and subsequently against the individual targets in secondary assays. Several novel active series were identified which inhibited TGR at a range of potencies, with IC50s ranging from micromolar to the assay response limit (∼25 nM). This is, to our knowledge, the first report of a large-scale HTS to identify lead compounds for a helminthic disease, and provides a paradigm that can be used to jump-start development of novel therapeutics for other neglected tropical diseases

Interactions between Natural Populations of Human and Rodent Schistosomes in the Lake Victoria Region of Kenya: A Molecular Epidemiological Approach

One of the world's most prevalent neglected diseases is schistosomiasis, which infects approximately 200 million people worldwide. Schistosoma mansoni is transmitted to humans by skin penetration by free-living larvae that develop in freshwater snails. The origin of this species is East Africa, where it coexists with its sister species, S. rodhaini. Interactions between these species potentially influence their epidemiology, ecology, and evolutionary biology, because they infect the same species of hosts and can hybridize. Over two years, we examined their distribution in Kenya to determine their degree of overlap geographically, within snail hosts, and in the water column as infective stages. Both species were spatially and temporally patchy, although S. mansoni was eight times more common than S. rodhaini. Both species overlap in the time of day they were present in the water column, which increases the potential for the species to coinfect the same host and interbreed. Peak infective time for S. mansoni was midday and dawn and dusk for S. rodhaini. Three snails were coinfected, which was more common than expected by chance. These findings indicate a lack of obvious isolating mechanisms to prevent hybridization, raising the intriguing question of how the two species retain separate identities

Whole genome analysis of a schistosomiasis-transmitting freshwater snail

Biomphalaria snails are instrumental in transmission of the human blood fluke Schistosoma mansoni. With the World Health Organization's goal to eliminate schistosomiasis as a global health problem by 2025, there is now renewed emphasis on snail control. Here, we characterize the genome of Biomphalaria glabrata, a lophotrochozoan protostome, and provide timely and important information on snail biology. We describe aspects of phero-perception, stress responses, immune function and regulation of gene expression that support the persistence of B. glabrata in the field and may define this species as a suitable snail host for S. mansoni. We identify several potential targets for developing novel control measures aimed at reducing snail-mediated transmission of schistosomiasis

Corrigendum: Whole genome analysis of a schistosomiasis-transmitting freshwater snail

This corrects the article DOI: 10.1038/ncomms15451