Soil-transmitted helminths and schistosomiasis among pre-school age children in a rural setting of Busia County, Western Kenya: a cross-sectional study of prevalence, and associated exposures.

BACKGROUND: Soil-transmitted helminths (STH) and schistosomiasis continue to cause serious health problems among affected communities. To ensure that infection transmission levels are reduced, repeated mass drug administration at regular intervals has been recommended by World Health Organization. Pre-school age children (PSAC) have been neglected both in terms of research activities and in control programmes in the past for reasons that they carry insignificant infection levels. The current study determined risk factors that contribute to differences in infection prevalence among enrolled and non-enrolled PSAC in Busia County, western Kenya. METHODS: This was a comparative cross-sectional study that compared STH and Schistosoma mansoni infections among enrolled and non-enrolled PSAC in Busia County. Simple random sampling was used to select study participants. A total of 327 enrolled and 326 non-enrolled PSAC (n = 653) were recruited from five participating schools, and the neighboring villages. Statistical analysis was performed using STATA version 14 (STATA Corporation, College Station, TX, USA). Differences in proportions were assessed using the z-test statistic for testing sample proportions. Univariable and multivariable logistic regression were used to test the associations between the variables. RESULTS: The prevalence of STH and Schistosoma mansoni infection was 17.0% (95%CI: 13.1-22.1), and 11.8% (95%CI:11.0-12.9) respectively. Specific STH species prevalence were 12.9% (95%CI:7.0-23.5) for Trichuris trichiura, 8.3% (95%CI:8.2-8.3) for Ascaris lumbricoides, and 1.2% (95%CI:1.2-1.2) for hookworms. Prevalence of T. trichiura was higher among enrolled PSAC 16.9% (95%CI: 6.8-41.9); p = 0.003, compared to the non-enrolled 8.9% (95%CI:4.3-18.2). From univariable analysis, lack of improved water source for drinking OR 2.01, (95%CI:1.29-3.13); p = 0.002, and not wearing shoes OR 3.42, (95%CI:1.14-10.29); p = 0.028, were some of the significant factors associated with STH infection. While for multivariable analysis, bathing/swimming in a river daily, aOR 3.99 (95%CI:1.98-8.06); p = 0.001 was a key significant factor for S. mansoni infections. CONCLUSION: There was high prevalence of STH infection among enrolled PSAC despite having participated in the national school-based deworming programme. Hence the need for continued mass drug administration to reduce the intensity of infections among these age group. In addition, further research maybe needed to identify drivers of STH infection particularly T. trichiura among PSAC.

High prevalence of helminths infection and associated risk factors among adults living in a rural setting, central Kenya: a cross-sectional study.

BACKGROUND: Schistosome infection and soil-transmitted helminths (STHs) are major public health problems in many developing countries where they contribute to the suffering of populations living in poor settings. A cross-sectional survey was conducted in four rural villages in central region of Kenya to provide information on the status of schistosome and STH infections. Previous studies conducted in the area among primary school children showed that there were high STH and Schistosoma mansoni infections. This paper presents the results of a parasitological investigation and the associated risk factors of infection among adults living in the study villages. METHODS: A total of 495 adults (18-84 years) from systematically selected households were sampled during this cross-sectional survey. They were interviewed and screened for S. mansoni and STHs using duplicate Kato-Katz thick smears. Comparison of prevalence by age group and gender was explored by confidence interval plots, and 95% CI were obtained by generalized least squares (GLS) random effects model. Risk factors associated with S. mansoni infection were determined using mixed effects logistic regression at 95% CI taking into account household clusters. RESULTS: The study revealed that the prevalence of S. mansoni infection was 33.5% (95% CI 29.6-38.0) among adults in the study villages, while the prevalence of STH infection was 0.2% (95% CI 0-1.4) with hookworm being the only detected STH species. However, the village and education level were the only risk factors which showed significant evidence of association with S. mansoni infections. CONCLUSIONS: The current study shows that adult communities in the study area were highly infected with S. mansoni. The study suggests that it may be necessary to develop contemporary approaches towards preventive chemotherapy interventions to adults in high endemic areas to complement the ongoing school-based deworming programme.

Assessment of lymphatic filariasis prior to re-starting mass drug administration campaigns in coastal Kenya.

BACKGROUND: Lymphatic filariasis (LF) is a debilitating disease associated with extensive disfigurement and is one of a diverse group of diseases referred to as neglected tropical diseases (NTDs) which mainly occur among the poorest populations. In line with global recommendations to eliminate LF, Kenya launched its LF elimination programme in 2002 with the aim to implement annual mass drug administration (MDA) in order to interrupt LF transmission. However, the programme faced financial and administrative challenges over the years such that sustained annual MDA was not possible. Recently, there has been renewed interest to eliminate LF and the Kenyan Ministry of Health, through support from World Health Organization (WHO), restarted annual MDA in 2015. The objective of this study was to evaluate the current status of LF infection in the endemic coastal region of Kenya before MDA campaigns were restarted. RESULTS: Ten sentinel sites in Kwale, Kilifi, Tana River, Lamu, and Taita-Taveta counties in coastal Kenya were selected for participation in a cross-sectional survey of LF infection prevalence. At least 300 individuals in each sentinel village were sampled through random house-to-house visits. During the day, the point-of-care immunochromatographic test (ICT) was used to detect the presence of Wuchereria bancrofti circulating filarial antigen in finger prick blood samples collected from residents of the selected sentinel villages. Those individuals who tested positive with the ICT test were requested to provide a night-time blood sample for microfilariae (MF) examination. The overall prevalence of filarial antigenaemia was 1.3% (95% CI: 0.9-1.8%). Ndau Island in Lamu County had the highest prevalence (6.3%; 95% CI: 4.1-9.7%), whereas sites in Kilifi and Kwale counties had prevalences < 1.7%. Mean microfilarial density was also higher in Ndau Island (234 MF/ml) compared to sentinel sites in Kwale and Kilifi counties (< 25 MF/ml). No LF infection was detected in Tana River and Taita-Taveta counties. Overall, more than 88% of the study participants reported to have used a bed net the previous night. CONCLUSIONS: Prevalence of LF infection is generally very low in coastal Kenya, but there remain areas that require further rounds of MDA if the disease is to be eliminated as a public health problem in line with the ongoing global elimination efforts. However, areas where there was no evidence of LF transmission should be considered for WHO-recommended transmission assessment surveys in view of stopping MDA.

Risk factors and spatial distribution of Schistosoma mansoni infection among primary school children in Mbita District, Western Kenya.

BACKGROUND: An increasing risk of Schistosoma mansoni infection has been observed around Lake Victoria, western Kenya since the 1970s. Understanding local transmission dynamics of schistosomiasis is crucial in curtailing increased risk of infection. METHODOLOGY/PRINCIPAL FINDINGS: We carried out a cross sectional study on a population of 310 children from eight primary schools. Overall, a total of 238 (76.8%) children were infected with S. mansoni, while seven (2.3%) had S. haematobium. The prevalence of hookworm, Trichuris trichiura and Ascaris lumbricoides were 6.1%, 5.2% and 2.3%, respectively. Plasmodium falciparum was the only malaria parasite detected (12.0%). High local population density within a 1 km radius around houses was identified as a major independent risk factor of S. mansoni infection. A spatial cluster of high infection risk was detected around the Mbita causeway following adjustment for population density and other potential risk factors. CONCLUSIONS/SIGNIFICANCE: Population density was shown to be a major factor fuelling schistosome infection while individual socio-economic factors appeared not to affect the infection risk. The high-risk cluster around the Mbita causeway may be explained by the construction of an artificial pathway that may cause increased numbers of S. mansoni host snails through obstruction of the waterway. This construction may have, therefore, a significant negative impact on the health of the local population, especially school-aged children who frequently come in contact with lake water.

Once a year school-based deworming with praziquantel and albendazole combination may not be adequate for control of urogenital schistosomiasis and hookworm infection in Matuga District, Kwale County, Kenya.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.