• A 5-Year intervention study on elimination of urogenital schistosomiasis in Zanzibar: Parasitological results of annual cross-sectional surveys

      Knopp, S; Ame, SM; Person, B; Hattendorf, J; Rabone, M; Juma, S; Muhsin, J; Khamis, IS; Hollenberg, E; Mohammed, KA; et al. (Public Library of Science (PLoS), 2019-05-06)
      Background The Zanzibar Elimination of Schistosomiasis Transmission (ZEST) project aimed to eliminate urogenital schistosomiasis as a public health problem from Pemba and to interrupt Schistosoma haematobium transmission from Unguja in 5 years. Methodology A repeated cross-sectional cluster-randomized trial was implemented from 2011/12 till 2017. On each island, 45 shehias were randomly assigned to receive one of three interventions: biannual mass drug administration (MDA) with praziquantel alone, or in combination with snail control or behavior change measures. In cross-sectional surveys, a single urine sample was collected from ~9,000 students aged 9- to 12-years and from ~4,500 adults aged 20- to 55-years annually, and from ~9,000 1st year students at baseline and the final survey. Each sample was examined for S. haematobium eggs by a single urine filtration. Prevalence and infection intensity were determined. Odds of infection were compared between the intervention arms. Principal findings Prevalence was reduced from 6.1% (95% confidence interval (CI): 4.5%-7.6%) to 1.7% (95% CI: 1.2%-2.2%) in 9- to 12-year old students, from 3.9% (95% CI: 2.8%-5.0%) to 1.5% (95% CI: 1.0%-2.0%) in adults, and from 8.8% (95% CI: 6.5%-11.2%) to 2.6% (95% CI: 1.7%-3.5%) in 1st year students from 2011/12 to 2017. In 2017, heavy infection intensities occurred in 0.4% of 9- to 12-year old students, 0.1% of adults, and 0.8% of 1st year students. Considering 1st year students in 2017, 13/45 schools in Pemba and 4/45 schools in Unguja had heavy infection intensities >1%. There was no significant difference in prevalence between the intervention arms in any study group and year. Conclusions/Significance Urogenital schistosomiasis was eliminated as public health problem from most sites in Pemba and Unguja. Prevalence was significantly reduced, but transmission was not interrupted. Continued interventions that are adaptive and tailored to the micro-epidemiology of S. haematobium in Zanzibar are needed to sustain and advance the gains made by ZEST.
    • Assessing the feasibility of interrupting the transmission of soil-transmitted helminths through mass drug administration: The DeWorm3 cluster randomized trial protocol

      Ásbjörnsdóttir, KH; Ajjampur, SSR; Anderson, RM; Bailey, R; Gardiner, I; Halliday, KE; Ibikounle, M; Kalua, K; Kang, G; Littlewood, T; et al. (2018-01-18)
    • Calculating the prevalence of soil-transmitted helminth infection through pooling of stool samples: Choosing and optimizing the pooling strategy

      Truscott, James; Dunn, Julia; PAPAIAKOVOU, MARINA; Schaer, Fabian; Werkman, Marleen; Littlewood, T; Walson, JL; Anderson, Roy (Public Library of Science (PLoS), 2019-03-21)
      Prevalence is a common epidemiological measure for assessing soil-transmitted helminth burden and forms the basis for much public-health decision-making. Standard diagnostic techniques are based on egg detection in stool samples through microscopy and these techniques are known to have poor sensitivity for individuals with low infection intensity, leading to poor sensitivity in low prevalence populations. PCR diagnostic techniques offer very high sensitivities even at low prevalence, but at a greater cost for each diagnostic test in terms of equipment needed and technician time and training. Pooling of samples can allow prevalence to be estimated while minimizing the number of tests performed. We develop a model of the relative cost of pooling to estimate prevalence, compared to the direct approach of testing all samples individually. Analysis shows how expected elative cost depends on both the underlying prevalence in the population and the size of the pools constructed. A critical prevalence level (approx. 31%) above which pooling is never cost effective, independent of pool size. When no prevalence information is available, there is no basis on which to choose between pooling and testing all samples individually. We recast our model of relative cost in a Bayesian framework in order to investigate how prior information about prevalence in a given population can be used to inform the decision to choose either pooling or full testing. Results suggest that if prevalence is below 10%, a relatively small exploratory prevalence survey (10–15 samples) can be sufficient to give a high degree of certainty that pooling may be relatively cost effective.
    • A Case of Urogenital Human Schistosomiasis from a Non-endemic Area

      Calvo-Cano, A; Cnops, L; Huyse, T; van Lieshout, L; Pardos, J; Valls, ME; Franco, A; Rollinson, D; Gascon, J; Jones, MK (2015-11-05)
    • Epidemiological Interactions between Urogenital and Intestinal Human Schistosomiasis in the Context of Praziquantel Treatment across Three West African Countries

      Knowles, SCL; Webster, BL; Garba, A; Sacko, M; Diaw, OT; Fenwick, A; Rollinson, D; Webster, JP; Raso, G (2015-10-15)
    • Reconstructing Colonization Dynamics of the Human Parasite Schistosoma mansoni following Anthropogenic Environmental Changes in Northwest Senegal

      Van den Broeck, F; Maes, GE; Larmuseau, MHD; Rollinson, D; Sy, I; Faye, D; Volckaert, FAM; Polman, K; Huyse, T; Correa-Oliveira, R (2015-08-14)
    • Sensitivity and Specificity of a Urine Circulating Anodic Antigen Test for the Diagnosis of Schistosoma haematobium in Low Endemic Settings

      Knopp, S; Corstjens, PLAM; Koukounari, A; Cercamondi, CI; Ame, SM; Ali, SM; de Dood, CJ; Mohammed, KA; Utzinger, J; Rollinson, D; et al. (2015-05-14)
    • Sustaining Progress towards NTD Elimination: An Opportunity to Leverage Lymphatic Filariasis Elimination Programs to Interrupt Transmission of Soil-Transmitted Helminths

      Means, AR; Asbjornsdottir, K; Mwandawiro, C; Rollinson, D; Jacobson, J; Littlewood, T; Walson, JL; Lammie, PJ (2016-07-14)