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.

No abstract

No abstract

No abstract

Abstract. The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) includes communitywide treatment in areas with 25% prevalence of schistosomiasis along the shores of Lake Victoria using community health workers (CHWs). The CHWs are key drivers in community-owned mass drug administration (MDA) intervention programs. We explored their experiences and perceptions after initial MDA participation. Unstructured open-ended group discussions were conducted after completion of MDA activities. Narratives were obtained from CHWs using a digital audio recorder during the group discussion, transcribed verbatim and translated into English where applicable. Thematic decomposition of data was done using ATLAS.t.i. software. From the perspective of the CHWs, factors influencing MDA compliance included drug side effects, food supply stability, and conspiracy theories about the "real" purpose of treatment. The interest of CHWs to serve as community drug distributors stemmed from both intrinsic and extrinsic factors. Feedback from CHWs can promote more effective MDA in rural Kenyan communities.

Schistosomiasis mansoni is usually a chronic infection that leads to long-term, systemic exposure to schistosome antigens. Experimental Schistosoma mansoni infection is associated with immunoregulatory mechanisms, including T regulatory cells (Treg) that may help control morbidity and dampen resistance to re-infection. We now show that some schistosomiasis mansoni patients have high proportions of CD3(+)/CD4(+)/CD25(high) Treg. On effective treatment with praziquantel, these high Treg percentages decrease, and fewer of the remaining Treg express CD45RO. The proportion of Treg in S. mansoni-infected patients is inversely related to their percentage of activated, putative effector T cells (CD3(+)/CD4(+)/CD25(medium)/HLA-DR(+) cells). We conclude some, but not all, schistosomiasis mansoni patients develop high percentages of circulating Treg, and effective treatment both decreases the levels of these cells and changes their phenotypes, possibly because of the removal of constant exposure to antigens from intravascular, egg-producing adult worms.

BackgroundAlthough schistosomiasis is generally considered a rural phenomenon, infections have been reported within urban settings. Based on observations of high prevalence of Schistosoma mansoni infection in schools within the informal settlements of Kisumu City, a follow-up malacological survey incorporating 81 sites within 6 informal settlements of the City was conducted to determine the presence of intermediate host snails and ascertain whether active transmission was occurring within these areas.MethodsSurveyed sites were mapped using a geographical information system. Cercaria shedding was determined from snails and species of snails identified based on shell morphology. Vegetation cover and presence of algal mass at the sites was recorded, and the physico-chemical characteristics of the water including pH and temperature were determined using a pH meter with a glass electrode and a temperature probe.ResultsOut of 1,059 snails collected, 407 (38.4%) were putatively identified as Biomphalaria sudanica, 425 (40.1%) as Biomphalaria pfeifferi and 227 (21.5%) as Bulinus globosus. The spatial distribution of snails was clustered, with few sites accounting for most of the snails. The highest snail abundance was recorded in Nyamasaria (543 snails) followed by Nyalenda B (313 snails). As expected, the mean snail abundance was higher along the lakeshore (18 ± 12 snails) compared to inland sites (dams, rivers and springs) (11 ± 32 snails) (F1, 79 = 38.8, P < 0.0001). Overall, 19 (1.8%) of the snails collected shed schistosome cercariae. Interestingly, the proportion of infected Biomphalaria snails was higher in the inland (2.7%) compared to the lakeshore sites (0.3%) (P = 0.0109). B. sudanica was more abundant in sites along the lakeshore whereas B. pfeifferi and B. globosus were more abundant in the inland sites. Biomphalaria and Bulinus snails were found at 16 and 11 out of the 56 inland sites, respectively.ConclusionsThe high abundance of Biomphalaria and Bulinus spp. as well as observation of field-caught snails shedding cercariae confirmed that besides Lake Victoria, the local risk for schistosomiasis transmission exists within the informal settlements of Kisumu City. Prospective control interventions in these areas need to incorporate focal snail control to complement chemotherapy in reducing transmission.

BackgroundThe Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was established in 2008 to answer strategic questions about schistosomiasis control. For programme managers, a high-priority question is: what are the most cost-effective strategies for delivering preventive chemotherapy (PCT) with praziquantel (PZQ)? This paper describes the process SCORE used to transform this question into a harmonized research protocol, the study design for answering this question, the village eligibility assessments and data resulting from the first year of the study.MethodsBeginning in 2009, SCORE held a series of meetings to specify empirical questions and design studies related to different schedules of PCT for schistosomiasis control in communities with high (gaining control studies) and moderate (sustaining control studies) prevalence of Schistosoma infection among school-aged children. Seven studies are currently being implemented in five African countries. During the first year, villages were screened for eligibility, and data were collected on prevalence and intensity of infection prior to randomisation and the implementation of different schemes of PZQ intervention strategies.ResultsThese studies of different treatment schedules with PZQ will provide the most comprehensive data thus far on the optimal frequency and continuity of PCT for schistosomiasis infection and morbidity control.ConclusionsWe expect that the study outcomes will provide data for decision-making for country programme managers and a rich resource of information to the schistosomiasis research community.Trial registrationThe trials are registered at International Standard Randomised Controlled Trial registry (identifiers: ISRCTN99401114, ISRCTN14849830, ISRCTN16755535, ISRCTN14117624, ISRCTN95819193 and ISRCTN32045736).