Influence of Exposure History on the Immunology and Development of Resistance to Human Schistosomiasis Mansoni

Schistosomiasis is a parasitic blood fluke infection of 200 million people worldwide. We have shown that humans can acquire immunity to reinfection after repeated exposures and cures with the drug praziquantel. The increase in resistance to reinfection was associated with an increase in schistosome-specific IgE. The ability to develop resistance and the rate at which resistance was acquired varied greatly in two cohorts of men within close geographic proximity and with similar occupational exposures to schistosomes. These differences are likely attributable to differences in history of exposure to Schistosoma mansoni infection and immunologic status at baseline, with those acquiring immunity faster having lifelong S. mansoni exposure and immunologic evidence of chronic S. mansoni infection. As many conflicting results have been reported in the literature regarding immunologic parameters associated with the development of resistance to schistosome infection, exposure history and prior immune status should be considered in the design of future immuno-epidemiologic studies

Evaluation of Urine CCA Assays for Detection of Schistosoma mansoni Infection in Western Kenya

Although accurate assessment of the prevalence of Schistosoma mansoni is important for the design and evaluation of control programs, the most widely used tools for diagnosis are limited by suboptimal sensitivity, slow turn-around-time, or inability to distinguish current from former infections. Recently, two tests that detect circulating cathodic antigen (CCA) in urine of patients with schistosomiasis became commercially available. As part of a larger study on schistosomiasis prevalence in young children, we evaluated the performance and diagnostic accuracy of these tests—the carbon test strip designed for use in the laboratory and the cassette format test intended for field use. In comparison to 6 Kato-Katz exams, the carbon and cassette CCA tests had sensitivities of 88.4% and 94.2% and specificities of 70.9% and 59.4%, respectively. However, because of the known limitations of the Kato-Katz assay, we also utilized latent class analysis (LCA) incorporating the CCA, Kato-Katz, and schistosome-specific antibody results to determine their sensitivities and specificities. The laboratory-based CCA test had a sensitivity of 91.7% and a specificity of 89.4% by LCA while the cassette test had a sensitivity of 96.3% and a specificity of 74.7%. The intensity of the reaction in both urine CCA tests reflected stool egg burden and their performance was not affected by the presence of soil transmitted helminth infections. Our results suggest that urine-based assays for CCA may be valuable in screening for S. mansoni infections

Examining the health and wellbeing of women sanitation workers in Ghana and Kenya

About 3.6 billion people worldwide lack access to safely managed sanitation service. To bridge service gaps, informal sanitation businesses have emerged as alternative service providers to meet the sanitation needs of unserved populations. Informal sanitation workers include persons who empty septic tanks, clean toilets, sewers, and manage public toilets. They provide a fundamental public service particularly in areas where access to municipal sanitation service is limited. Through qualitative methodologies, this paper explores the lived experiences and associated health risks of women working in the informal sanitation sector in urban Ghana and Kenya. Our findings show that female informal sanitation workers were exposed to injuries and infections, stigma and discrimination, emotional and psychological distress, sexual harassment, and unhealthy coping strategies. Distinctively, younger female participants were more likely to experience sexual harassment. Because of social stigma, many of the women developed unsafe work practices such as refusal to wear PPE and working at night. By paying close attention to the embodied effects of informal sanitation work, we can better comprehend the daily politics, lived experiences, and urban social infrastructure regimes that have a significant impact on the quality of life of informal sanitation workers. The results are also crucial for developing programs for women's empowerment and labour and social protection policies, especially in lowincome settings where gender norms interact with income disparities and other sociopolitical issues to affect women's participation in the labor market

Using Photovoice as a Community Based Participatory Research Tool for Changing Water, Sanitation, and Hygiene Behaviours in Usoma, Kenya

Recent years have witnessed an increase in the use of community based participatory research (CBPR) tools for understanding environment and health issues and facilitating social action. This paper explores the application and utility of photovoice for understanding water, sanitation, and hygiene (WASH) behaviours and catalysing community led solutions to change behaviours. Between June and August 2013, photovoice was conducted with eight (8) women in Usoma, a lakeshore community in Western Kenya with a follow-up community meeting (baraza) in May 2014 to discuss findings with the community members and government officials. In the first part of the study, photovoice one-on-one interviews were used to explore local perceptions and practices around water-health linkages and how the ecological and socio-political environment shapes these perceptions and practices. This paper, which is the second component of the study, uses photovoice group discussions to explore participants’ experiences with and (re)action to the photographs and the photovoice project. The findings illustrate that photovoice was an effective CBPR methodology for understanding behaviours, creating awareness, facilitating collective action, and engaging with local government and local health officials at the water-health nexus

Using Photovoice as a Community Based Participatory Research Tool for Changing Water, Sanitation, and Hygiene Behaviours in Usoma, Kenya

Recent years have witnessed an increase in the use of community based participatory research (CBPR) tools for understanding environment and health issues and facilitating social action. This paper explores the application and utility of photovoice for understanding water, sanitation, and hygiene (WASH) behaviours and catalysing community led solutions to change behaviours. Between June and August 2013, photovoice was conducted with eight (8) women in Usoma, a lakeshore community in Western Kenya with a follow-up community meeting (baraza) in May 2014 to discuss findings with the community members and government officials. In the first part of the study, photovoice one-on-one interviews were used to explore local perceptions and practices around water-health linkages and how the ecological and socio-political environment shapes these perceptions and practices. This paper, which is the second component of the study, uses photovoice group discussions to explore participants' experiences with and (re)action to the photographs and the photovoice project. The findings illustrate that photovoice was an effective CBPR methodology for understanding behaviours, creating awareness, facilitating collective action, and engaging with local government and local health officials at the water-health nexus

Use of geospatial modeling to predict Schistosoma mansoni prevalence in Nyanza Province, Kenya.

BACKGROUND: Schistosomiasis, a parasitic disease that affects over 200 million people, can lead to significant morbidity and mortality; distribution of single dose preventative chemotherapy significantly reduces disease burden. Implementation of control programs is dictated by disease prevalence rates, which are determined by costly and labor intensive screening of stool samples. Because ecological and human factors are known to contribute to the focal distribution of schistosomiasis, we sought to determine if specific environmental and geographic factors could be used to accurately predict Schistosoma mansoni prevalence in Nyanza Province, Kenya. METHODOLOGY/PRINCIPAL FINDINGS: A spatial mixed model was fit to assess associations with S. mansoni prevalence in schools. Data on S. mansoni prevalence and GPS location of the school were obtained from 457 primary schools. Environmental and geographic data layers were obtained from publicly available sources. Spatial models were constructed using ArcGIS 10 and R 2.13.0. Lower S.mansoni prevalence was associated with further distance (km) to Lake Victoria, higher day land surface temperature (LST), and higher monthly rainfall totals. Altitude, night LST, human influence index, normalized difference vegetation index, soil pH, soil texture, soil bulk density, soil water capacity, population, and land use variables were not significantly associated with S. mansoni prevalence. CONCLUSIONS: Our model suggests that there are specific environmental and geographic factors that influence S. mansoni prevalence rates in Nyanza Province, Kenya. Validation and use of schistosomiasis prevalence maps will allow control programs to plan and prioritize efficient control campaigns to decrease schistosomiasis burden

Cluster randomized trial comparing school-based mass drug administration schedules in areas of western Kenya with moderate initial prevalence of <i>Schistosoma mansoni</i> infections

<div><p>Background</p><p>Mass drug administration (MDA) using praziquantel is the WHO-recommended approach for control of schistosomiasis. However, few studies have compared the impact of different schedules of MDA on the resultant infection levels. We wished to evaluate whether annual MDA was more effective than less frequent treatments for reducing community-level prevalence and intensity of <i>Schistosoma mansoni</i> infections.</p><p>Methods</p><p>We performed a cluster randomized trial (ISRCTN 14849830) of 3 different MDA frequencies over a 5 year period in 75 villages with moderate (10%-24%) initial prevalence of <i>S</i>. <i>mansoni</i> in school children in western Kenya. Praziquantel was distributed by school teachers to students either annually, the first 2 years, or every other year over a 4 year period. Prevalence and intensity of infection were measured by stool examination in 9–12 year old students using the Kato-Katz method at baseline, each treatment year, and for the final evaluation at year 5. <i>S</i>. <i>mansoni</i> prevalence and intensity were also measured in first year students at baseline and year 5.</p><p>Results</p><p>Twenty-five schools were randomly assigned to each arm. <i>S</i>. <i>mansoni</i> prevalence and infection intensity in 9–12 year old students significantly decreased within each arm from baseline to year 5 but there were no differences between arms. There were no differences in infection levels in first year students either within or between arms.</p><p>Conclusions</p><p>Strategies employing 2 or 4 rounds of MDA had a similar impact in schools with moderate initial prevalence, suggesting that schistosomiasis control can be sustained by school-based MDA, even if provided only every other year.</p></div

Prevalence and intensity of <i>S</i>. mansoni infection for first year students in each arm at baseline (Year 1) and final evaluation (Year 5).

<p>Prevalence and intensity of <i>S</i>. mansoni infection for first year students in each arm at baseline (Year 1) and final evaluation (Year 5).</p