Search

Schistosomiasis is a chronic parasitic disease caused by a digenetic trematode blood fluke of the genus Schistosoma. The disease remains a serious public health problem in endemic countries and affects at least 207 million people worldwide, with 85% in Africa. In Kenya, more than 3.5 million are infected. A definite diagnosis of the disease plays a key role in the control of schistosomiasis. The detection of Schistosome Circulating antigens is an effective approach to discriminate previous exposure and current infection. Simple, non-invasive tools for detection of S. mansoni would be highly valuable with the view of post-intervention assessment in programmes but also for treatment/re-treatment of the individual patient. The study was conducted in Makueni, a low infection area (6 to 90 years old). The prevalence was 56.4% after three consecutive Kato-Katz stools. A population sample of n= 521 individuals was selected from an initial study cohort in an epidemiological follow-up of Schistosome infections in this foci. All the subjects in the sub-sample had been treated with praziquantel 40 mg/kg. The study was to determine the prevalence of S. mansoni using Kato technique and CCA (Circulating Cathodic Antigen) urine Elisa strips at baseline and 24 hours then also at 2 years later. The cohort study population at baseline had a prevalence of 62% of the schistosomiasis infection. The detection of schistosomiasis CCA at baseline using the CCA Elisa strip on urine samples gave a prevalence of 71.9%. The CCA was determined 24 hours after treatment with PZQ and the prevalence was 44.1%. In conclusion, Kitengei village is low endemic for schistosomiasis. Finally, circulating cathodic antigen can be used as a diagnostic tool, for the follow-up of chemotherapy and re-infection and as a field test and/or screening tool in control programmes.

Schistosomiasis is a waterborne, infectious disease with high morbidity and significant economic burdens affecting more than 250 million people globally. Disease control has, with notable success, for decades focused on drug treatment of infected human populations, but a recent paradigm shift now entails moving from control to elimination. To achieve this ambitious goal more sensitive diagnostic tools are needed to monitor progress towards transmission interruption in the environment, especially in low-intensity infection areas. We report on the development of an environmental DNA (eDNA) based tool to efficiently detect DNA traces of the parasite Schistosoma mansoni directly in the aquatic environment, where the non-human part of the parasite life cycle occurs. To our knowledge, this is the first report of the successful detection of S. mansoni in freshwater samples using aquatic eDNA. True eDNA was detected in as few as 10 cercariae/L water in laboratory experiments. The field applicability of the method was tested at known transmission sites in Kenya, where comparison of schistosome detection by conventional snail surveys (snail collection and cercariae shedding) with eDNA (water samples) showed 71% agreement between the methods. The eDNA method furthermore detected schistosome presence at two additional sites where snail shedding failed, demonstrating a higher sensitivity of eDNA sampling. We conclude that eDNA provides a promising new tool to significantly improve the environmental surveillance of S. mansoni. Given the proper method and guideline development, eDNA could become an essential future component of the schistosomiasis control tool box needed to achieve the goal of elimination.SignificanceAccurate detection and delineation of schistosomiasis transmission sites will be vital in on-going efforts to control and ultimately eliminate one of the most neglected tropical parasitic diseases affecting more than 250 million people worldwide. Conventional methods to detect parasites in the environment are cumbersome and have low sensitivity. We therefore developed an environmental DNA (eDNA) based method for schistosome detection in aquatic environments. Aquatic eDNA showed higher sensitivity than conventional snail surveys. We conclude that eDNA is a promising non-invasive and sensitive tool for environmental surveillance of schistosomiasis transmission. As the efforts and aims to control the disease are transitioning towards complete transmission interruption, this could be the robust and cost-effective surveillance tool needed in the “end game” of schistosomiasis.

Schistosomiasis is a water-based, infectious disease with high morbidity and significant economic burdens affecting >250 million people globally. Disease control has, with notable success, for decades focused on drug treatment of infected human populations, but a recent paradigm shift now entails moving from control to elimination. To achieve this ambitious goal, more sensitive diagnostic tools are needed to monitor progress toward transmission interruption in the environment, especially in low-intensity infection areas. We report on the development of an environmental DNA (eDNA)-based tool to efficiently detect DNA traces of the parasite Schistosoma mansoni directly in the aquatic environment, where the nonhuman part of the parasite life cycle occurs. This is a report of the successful detection of S. mansoni in freshwater samples by using aquatic eDNA. True eDNA was detected in as few as 10 cercariae per liter of water in laboratory experiments. The field applicability of the method was tested at known transmission sites in Kenya, where comparison of schistosome detection by conventional snail surveys (snail collection and cercariae shedding) with eDNA (water samples) showed 71% agreement between the methods. The eDNA method furthermore detected schistosome presence at two additional sites where snail shedding failed, demonstrating a higher sensitivity of eDNA sampling. We conclude that eDNA provides a promising tool to substantially improve the environmental surveillance of S. mansoni. Given the proper method and guideline development, eDNA could become an essential future component of the schistosomiasis control tool box needed to achieve the goal of elimination.

Background The implementation of soil-transmitted helminth (STH) treatment programmes occurs in varied environmental, social and economic contexts. Programme impact will be influenced by factors that affect the reduction in the prevalence and intensity of infections following treatment, as well as the subsequent rate of reinfection. To better understand the heterogeneity of programme impact and its underlying reasons, we investigated the influence of contextual factors on reduction in STH infection as part of the national school based deworming (SBD) programme in Kenya. Materials and Methods Data on the prevalence and intensity of infection were collected within the monitoring and evaluation component of the SBD programme at baseline and after delivery of two annual treatment rounds in 153 schools in western Kenya. Using a framework that considers STH epidemiology and transmission dynamics, capacity to deliver treatment, operational feasibility and financial capacity, data were assembled at both school and district (county) levels. Geographic heterogeneity of programme impact was assessed by descriptive and spatial analyses. Factors associated with absolute reductions of Ascaris lumbricoides and hookworm infection prevalence and intensity were identified using mixed effects linear regression modelling adjusting for baseline infection levels. Principal Findings The reduction in prevalence and intensity of A. lumbricoides and hookworms varied significantly by county and within counties by school. Multivariable analysis of factors associated with programme impact showed that absolute A. lumbricoides reductions varied by environmental conditions and access to improved sanitation at schools or within the community. Larger reduction in prevalence and intensity of hookworms were found in schools located within areas with higher community level access to improved sanitation and within counties with higher economic and health service delivery indicator scores. Conclusions The study identifies factors associated with the impact of school-based deworming and in particular highlights how access to water, sanitation and hygiene and environmental conditions influence the impact of deworming programmes., Author Summary Most countries with endemic soil-transmitted helminth (STH) infections have started implementing deworming programmes in recent years. However, the achievable impact on the prevalence and intensity of infections will depend on the socioeconomic and environmental context in which the programme is implemented. We use a previously developed framework that considers the epidemiology of STH transmission, capacity to deliver treatment, operational and financial feasibility, to investigate reasons for the observed within-country variation of deworming programme impact based on data from the national school based deworming programme in Kenya. The study demonstrates that programme impact varied markedly within the country and that reductions in STH infection were associated with levels of access to water, sanitation and hygiene (at schools or within communities). The described framework can help to identify areas where lower programme impact can be expected, and also to determine which additional interventions should be implemented in support of the deworming efforts.

Background\ud \ud Neglected tropical diseases (NTDs) predominantly occur in resource poor settings where they often present a serious public health burden. Sustained global advocacy has been important in raising awareness of NTDs and the relatively low cost for control of helminthic NTDs using preventive chemotherapy. This enthusiasm was boosted at the London declaration on NTDs in 2012 through commitments by different partners to avail resources required for control of NTDs particularly those that employ preventive chemotherapy as the major intervention strategy. Subsequently, national NTD programmes are responding to these new opportunities by implementing preventive chemotherapy including school-based deworming (SBD). Further, with the availability of increased resources, both financial and pharma, the optimal strategies for implementing preventive chemotherapy in highly endemic settings are under debate and this paper goes some way to addressing this issue in a specific setting in coastal Kenya.\ud \ud Methods\ud \ud We conducted a repeated cross-sectional study in Matuga District, Kwale County, Kenya to evaluate the effect of school-based co-administration of praziquantel and albendazole against urogenital schistosomiasis and soil-transmitted helminth (STH) infections. A total of 1022 school children in 5 study schools were tested for the infections in urine and stool samples during a baseline survey in September 2009. The presence of Schistosoma haematobium infection was determined by the urine filtration method while STH infections were determined by Kato-Katz technique.\ud \ud Results\ud \ud Urogenital schistosomiasis and hookworm infection were the major parasitic infections among the children in the study area. There was significant decrease in both prevalence and intensity of S. haematobium infection after treatment but varying levels of rebound were observed during the period between the treatments. The school-based treatment, however, did not have any significant effect on both the prevalence and intensity of hookworm infection.\ud \ud Conclusions\ud \ud Once per year SBD programmes may not be adequate for controlling hookworm infection and urogenital schistosomiasis in rural areas of Kwale County. There is a need to consider expanded preventive chemotherapy strategies that will allow inclusion of the adult populations. Community-based health education campaigns focusing on increasing household latrine ownership and use, as a complementary measure to control STH and urogenital schistosomiasis in similar settings, may also be useful.

Background\ud \ud Soil-transmitted helminths and schistosomiasis are mostly prevalent in developing countries due to poor sanitation and lack of adequate clean water. School-age children tend to be the target of chemotherapy-based control programmes because they carry the heaviest worm and egg burdens. The present study examines adverse events (AEs) experienced following co-administration of albendazole and praziquantel to school-age children in a rural area in Kwale County, Kenya.\ud \ud Methods\ud \ud Children were treated with single doses of albendazole and praziquantel tablets and then interviewed using a questionnaire for post treatment AEs.\ud \ud Results\ud \ud Overall, 752 children, 47.6% boys, participated in the study. Their median (interquartile range) age was 12.0 (10.0–14.0) years. A total of 190 (25.3%) children reportedly experienced at least one AE. In total, 239 cases of AEs were reported with the most frequent being abdominal pains (46.3%), dizziness (33.2%) and nausea (21.1%). Majority of the reported AEs (80.8%) resolved themselves while 12.1% and 6.3% were countered by, respectively, self-medication and visiting a nearby health facility. More girls (60.5%) than boys (39.5%) reported AEs (P = 0.027).\ud \ud Conclusions\ud \ud The AEs were mild and transient, and were no worse than those expected following monotherapy. The current study adds to the evidence base that dual administration of albendazole and praziquantel in school-based mass drug administration is safe with only mild adverse events noted.

Background Schistosome and soil-transmitted helminth (STH) infections are recognized as major global public health problems, causing severe and subtle morbidity, including significant educational and nutritional effects in children. Although effective and safe drugs are available, ensuring access to these drugs by all those at risk of schistosomiasis and STHs is still a challenge. Community-directed intervention (CDI) has been used successfully for mass distribution of drugs for other diseases such as onchocerciasis and lymphatic filariasis. A national control programme is yet to be instituted in Kenya and evidence for cost-effective strategies for reaching most affected communities is needed. This study evaluated the effectiveness and feasibility of the CDI strategy in the control of schistosomiasis and STHs, in East Uyoma location, Rarieda district, a community of western Kenya that is highly endemic for both infections. Results Pre-treatment prevalence of S. mansoni averaged 17.4% (range 5-43%) in the entire location. Treatment coverage in different villages ranged from 54.19 to 96.6% by community drug distributor (CDD) records. Assessment from a household survey showed coverage of 52.3 -91.9% while the proportion of homesteads (home compounds) covered ranged from 54.9-98.5%. Six months after one round of drug distribution, the prevalence levels of S. mansoni, hookworm and Trichuris trichura infections were reduced by 33.2%, 69.4% and 42.6% respectively. Conclusions This study shows that CDI is an accepted and effective strategy in the mass treatment of schistosomiasis and STH infections in resource constrained communities in Kenya and may be useful in similar communities elsewhere. A controlled trial comparing CDI and school based mass drug administration to demonstarte their relative advantages is ongoing.

Background Neglected tropical diseases (NTDs) are major public health problems in developing countries where they contribute to suffering of populations living in poor settings. As part of a research project started in September 2009 in Kwale district, Coast Region, Kenya, a baseline cross-sectional survey was conducted in 5 rural villages to provide information on the status of NTDs, including urinary schistosomiasis, soil-transmitted helminthiasis (STH), and lymphatic filariasis. This paper presents the results of a parasitological investigation among adults in the study villages. Methods A total of 599 adults in the 5 study villages were tested for NTD infections in urine, stool and blood. The presence of Schistosoma haematobium infection was determined by the urine filtration method. The presence of STH in stool was determined by Kato-Katz method while filarial antigenaemia was determined using immunochromatographic (ICT) test. Results The study revealed high prevalence of hookworm (41.7%) and schistosomiasis (18.2%) infections among adults in the study villages. Of the 599 individuals examined, 50.1% had one or more helminthic infections. There was low level of polyparasitism with helminthic NTDs in the study population with 9.5% and 1.7% of the participants having two and three infections, respectively. Conclusions In the current study, hookworm and schistosomiasis infections were identified as important infections among adults living in areas of high endemicity for these infections. Thus, if this section of the population is left untreated it may remain an important potential reservoir and a source of re-infection for school-age children treated in school deworming programmes. Therefore, there is a need to design novel strategies for preventive chemotherapy interventions that could allow inclusion of adults in an effort to reduce force of infection in high endemic communities.

The pre- and post-treatment level of eosinophiluria, as measured indirectly by the amount of free or cell bound eosinophil cationic protein (ECP) and eosinophil protein X (EPX) in urine from Schistosoma haematobium-infected Kenyan school children, were measured and compared with intensity of infection (eggs/10 ml of urine), albuminuria and pathological changes as detected by ultrasonography. ECP and EPX were determined by means of specific ELISA methods and levels were determined in both urine supernatants and extracted urine deposits (cells and cell debris). The level of ECP was significantly raised in urine supernatants from infected children compared to controls, whereas high amounts of EPX were found in urine supernatants from infected children as well as from controls. However, the amounts of cell bound ECP and EPX were significantly raised in infected children. In pre-treatment observations significant correlations were demonstrated between egg counts, albuminuria and eosinophiluria as measured by the amount of cell bound ECP and EPX, or ECP in urine supernatants. No such correlations were demonstrated with the amount of EPX in the urine supernatants. Comparable amounts of ECP and EPX could be extracted from the urine deposits from infected children, but due to the high amounts of EPX in urine deposit extracts from controls, extracted ECP gave the best discrimination between infected and non-infected children. While albuminuria disappeared in most children at the 6 week post-treatment follow-up, eosinophiluria persisted in a significant proportion of the treated children indicating continued eosinophil activity in the bladder wall. Detection and quantification of early acute inflammatory reactions using ECP/eosinophils in combination with detection of later stages of bladder pathology using ultrasound may allow for a dynamic evaluation of the pathological process, the morbidity development and post treatment pathological changes in S. haematobium infections.

Objective To design and implement surveys of malaria infection and coverage of malaria control interventions among school children in Kenya in order to contribute towards a nationwide assessment of malaria. Methods The country was stratified into distinct malaria transmission zones based on a malaria risk map and 480 schools were visited between October 2008 and March 2010. Surveys were conducted in two phases: an initial opportunistic phase whereby schools were selected for other research purposes; and a second phase whereby schools were purposively selected to provide adequate spatial representation across the country. Consent for participation was based on passive, opt-out consent rather than written, opt-in consent because of the routine, low-risk nature of the survey. All children were diagnosed for Plasmodium infection using rapid diagnostic tests, assessed for anaemia and were interviewed about mosquito net usage, recent history of illness, and socio-economic and household indicators. Children's responses were entered electronically in the school and data transmitted nightly to Nairobi using a mobile phone modem connection. RDT positive results were corrected by microscopy and all results were adjusted for clustering using random effect regression modelling. Results 49,975 children in 480 schools were sampled, at an estimated cost of US$ 1,116 per school. The overall prevalence of malaria and anaemia was 4.3% and 14.1%, respectively, and 19.0% of children reported using an insecticide-treated net (ITN). The prevalence of infection showed marked variation across the country, with prevalence being highest in Western and Nyanza provinces, and lowest in Central, North Eastern and Eastern provinces. Nationally, 2.3% of schools had reported ITN use >60%, and low reported ITN use was a particular problem in Western and Nyanza provinces. Few schools reported having malaria health education materials or ongoing malaria control activities. Conclusion School malaria surveys provide a rapid, cheap and sustainable approach to malaria surveillance which can complement household surveys, and in Kenya, show that large areas of the country do not merit any direct school-based control, but school-based interventions, coupled with strengthened community-based strategies, are warranted in western and coastal Kenya. The results also provide detailed baseline data to inform evaluation of school-based malaria control in Kenya.

Understanding the dynamics of schistosome infections is problematic because direct measurements of worm burden are not possible. Hitherto, the relative intensity of infection has been estimated by the number of parasite eggs excreted. Egg excretion is assumed to have a consistent relationship with worm burden with duration of infection. We have tested this assumption in Schistosoma mansoni- and S. haematobium-infected populations by looking at the relationships between a circulating parasite antigen, egg excretion level, host age, and parasite density. The study was carried out in two populations because experimental models suggested that S. haematobium but not S. mansoni suffers immune-mediated reduction of fecundity. The results were consistent with this observation, showing that S. mansoni egg output remains stable irrespective of host age or infection intensity while S. haematobium has a substantially reduced egg production with host age. This information is fundamental to understanding the immunology and epidemiology of human schistosomiasis and thus practical approaches to disease control.

Background In 2012, the Kenyan Ministries of Health and of Education began a programme to deworm all school-age children living in areas at high risk of soil-transmitted helminths (STH) and schistosome infections. The impact of this school-based mass drug administration (MDA) programme in Kenya is monitored by the Kenya Medical Research Institute (KEMRI) as part of a five-year (2012–2017) study. This article focuses on the impact of MDA on STH infections and presents the overall achieved reductions from baseline to mid-term, as well as yearly patterns of reductions and subsequent re-infections per school community. Methods The study involved a series of pre- and post-intervention, repeat cross-sectional surveys in a representative, stratified, two-stage sample of schools across Kenya. The programme contained two tiers of monitoring; a national baseline and mid-term survey including 200 schools, and surveys conducted among 60 schools pre- and post-intervention. Stool samples were collected from randomly selected school children and tested for helminth infections using Kato-Katz technique. The prevalence and mean intensity of each helminth species were calculated at the school and county levels and 95 % confidence intervals (CIs) were obtained by binomial and negative binomial regression, respectively, taking into account clustering by schools. Results The overall prevalence of STH infection at baseline was 32.3 % (hookworms: 15.4 %; Ascaris lumbricoides: 18.1 %; and Trichuris trichiura: 6.7 %). After two rounds of MDA, the overall prevalence of STH had reduced to 16.4 % (hookworms: 2.3 %; A. lumbricoides: 11.9 %; and T. trichiura: 4.5 %). The relative reductions of moderate to heavy intensity of infections were 33.7 % (STH combined), 77.3 % (hookworms) and 33.9 % (A. lumbricoides). For T. trichiura, however, moderate to heavy intensity of infections increased non-significantly by 18.0 % from baseline to mid-term survey. Conclusion The school-based deworming programme has substantially reduced STH infections, but because of ongoing transmission additional strategies may be required to achieve a sustained interruption of transmission. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1679-y) contains supplementary material, which is available to authorized users.

BACKGROUND: An increasing number of countries in Africa and elsewhere are developing national plans for the control of neglected tropical diseases. A key component of such plans is school-based deworming (SBD) for the control of soil-transmitted helminths (STHs) and schistosomiasis. Monitoring and evaluation (M&E) of national programmes is essential to ensure they are achieving their stated aims and to evaluate when to reduce the frequency of treatment or when to halt it altogether. The article describes the M&E design of the Kenya national SBD programme and presents results from the baseline survey conducted in early 2012. METHODS: The M&E design involves a stratified series of pre- and post-intervention, repeat cross-sectional surveys in a representative sample of 200 schools (over 20,000 children) across Kenya. Schools were sampled based on previous knowledge of STH endemicity and were proportional to population size. Stool (and where relevant urine) samples were obtained for microscopic examination and in a subset of schools; finger-prick blood samples were collected to estimate haemoglobin concentration. Descriptive and spatial analyses were conducted. The evaluation measured both prevalence and intensity of infection. RESULTS: Overall, 32.4% of children were infected with at least one STH species, with Ascaris lumbricoides as the most common species detected. The overall prevalence of Schistosoma mansoni was 2.1%, while in the Coast Province the prevalence of S. haematobium was 14.8%. There was marked geographical variation in the prevalence of species infection at school, district and province levels. The prevalence of hookworm infection was highest in Western Province (25.1%), while A. lumbricoides and T. trichiura prevalence was highest in the Rift Valley (27.1% and 11.9%). The lowest prevalence was observed in the Rift Valley for hookworm (3.5%), in the Coast for A. lumbricoides (1.0%), and in Nyanza for T. trichiura (3.6%). The prevalence of S. mansoni was most common in Western Province (4.1%). CONCLUSIONS: The current findings are consistent with the known spatial ecology of STH and schistosome infections and provide an important empirical basis on which to evaluate the impact of regular mass treatment through the school system in Kenya.

Background Reliable and updated maps of helminth (worm) infection distributions are essential to target control strategies to those populations in greatest need. Although many surveys have been conducted in endemic countries, the data are rarely available in a form that is accessible to policy makers and the managers of public health programmes. This is especially true in sub-Saharan Africa, where empirical data are seldom in the public domain. In an attempt to address the paucity of geographical information on helminth risk, this article describes the development of an updated global atlas of human helminth infection, showing the example of East Africa. Methods Empirical, cross-sectional estimates of infection prevalence conducted since 1980 were identified using electronic and manual search strategies of published and unpublished sources. A number of inclusion criteria were imposed for identified information, which was extracted into a standardized database. Details of survey population, diagnostic methods, sample size and numbers infected with schistosomes and soil-transmitted helminths were recorded. A unique identifier linked each record to an electronic copy of the source document, in portable document format. An attempt was made to identify the geographical location of each record using standardized geolocation procedures and the assembled data were incorporated into a geographical information system. Results At the time of writing, over 2,748 prevalence surveys were identified through multiple search strategies. Of these, 2,612 were able to be geolocated and mapped. More than half (58%) of included surveys were from grey literature or unpublished sources, underlining the importance of reviewing in-country sources. 66% of all surveys were conducted since 2000. Comprehensive, countrywide data are available for Burundi, Rwanda and Uganda. In contrast, information for Kenya and Tanzania is typically clustered in specific regions of the country, with few records from areas with very low population density and/or environmental conditions which are unfavourable for helminth transmission. Information is presented on the prevalence and geographical distribution for the major helminth species. Conclusion For all five countries, the information assembled in the current atlas provides the most reliable, up-to-date and comprehensive source of data on the distribution of common helminth infections to guide the rational implementation of control efforts.