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Regular treatment with praziquantel (PZQ) is the strategy for human schistosomiasis control aiming to prevent morbidity in later life. With the recent resolution on schistosomiasis elimination by the 65th World Health Assembly, appropriate diagnostic tools to inform interventions are keys to their success. We present a discrete Markov chains modelling framework that deals with the longitudinal study design and the measurement error in the diagnostic methods under study. A longitudinal detailed dataset from Uganda, in which one or two doses of PZQ treatment were provided, was analyzed through Latent Markov Models (LMMs). The aim was to evaluate the diagnostic accuracy of Circulating Cathodic Antigen (CCA) and of double Kato-Katz (KK) faecal slides over three consecutive days for Schistosoma mansoni infection simultaneously by age group at baseline and at two follow-up times post treatment. Diagnostic test sensitivities and specificities and the true underlying infection prevalence over time as well as the probabilities of transitions between infected and uninfected states are provided. The estimated transition probability matrices provide parsimonious yet important insights into the re-infection and cure rates in the two age groups. We show that the CCA diagnostic performance remained constant after PZQ treatment and that this test was overall more sensitive but less specific than single-day double KK for the diagnosis of S. mansoni infection. The probability of clearing infection from baseline to 9 weeks was higher among those who received two PZQ doses compared to one PZQ dose for both age groups, with much higher re-infection rates among children compared to adolescents and adults. We recommend LMMs as a useful methodology for monitoring and evaluation and treatment decision research as well as CCA for mapping surveys of S. mansoni infection, although additional diagnostic tools should be incorporated in schistosomiasis elimination programs. [ABSTRACT FROM AUTHOR]

Background: Schistosomiasis and soil-transmitted helminthiasis (STH) are among the neglected tropical diseases in Africa. A national control program for these diseases was initiated in Uganda during March 2003. Annual treatment with praziquantel and albendazole was given to schoolchildren in endemic areas and to adults in selected communities where local prevalence of Schistosoma mansoni in schoolchildren was high. Methods: The impact of the treatment program was monitored through cohorts of schoolchildren and adults. Their infection status with S. mansoni and STH was determined by parasitological examinations at baseline and at annual follow-ups. The prevalence and intensity of S. mansoni and STH before and after treatment were analyzed. Results: Two rounds of treatment significantly reduced the prevalence of S. mansoni infection in schoolchildren across three regions in the country from 33.4-49.3% to 9.7-29.6%, and intensity of infection from 105.7-386.8 eggs per gram of faeces (epg) to 11.6-84.1 epg. The prevalence of hookworm infection was reduced from 41.2-57.9% to 5.5-16.1%, and intensity of infection from 186.9-416.8 epg to 3.7-36.9 epg. The proportion of children with heavy S. mansoni infection was significantly reduced from 15% (95% CI 13.4-16.8%) to 2.3% (95% CI 1.6-3.0%). In adults, significant reduction in the prevalence and intensity of S. mansoni and hookworm infections was also observed. More importantly, the prevalence and intensity of both S. mansoni and hookworm infections in the cohorts of newly-recruited 6-year-olds who had never previously received treatment decreased significantly over 2 years: 34.9% (95% CI 31.9-37.8%) to 22.6% (95% CI 19.9-25.2%) and 171.1 epg (95% CI 141.5-200.7) to 72.0 epg (95% CI 50.9-93.1) for S. mansoni; and 48.4% (95% CI 45.4-51.5) to 15.9% (95% CI 13.6-18.2) and 232.7 epg (95% CI 188.4-276.9) to 51.4 epg (95% CI 33.4-69.5) for hookworms, suggesting a general decline in environmental transmission levels. Conclusion: Annual anthelminthic treatment delivered to schoolchildren and to adults at high risk in Uganda can significantly reduce the prevalence and intensity of infection for schistosomiasis and STH, and potentially also significantly reduce levels of environmental transmission of infection. [ABSTRACT FROM AUTHOR]

Programmatic surveillance of intestinal schistosomiasis during control can typically use four diagnostic tests, either singularly or in combination, but these have yet to be cross-compared directly. Our study assembled a complete diagnostic dataset, inclusive of infection intensities, from 258 children from five Ugandan primary schools. The schools were purposely selected as typical of the endemic landscape near Lake Albert and reflective of high- and low-transmission settings. Overall prevalence was: 44.1% (95% CI 38.0-50.2) by microscopy of duplicate Kato-Katz smears from two consecutive stools, 56.9% (95% CI 50.8-63.0) by urine-circulating cathodic antigen (CCA) dipstick, 67.4% (95% CI 61.6-73.1) by DNA-TaqMan® and 75.1% (95% CI 69.8-80.4) by soluble egg antigen enzyme-linked immunosorbent assay (SEA-ELISA). A cross-comparison of diagnostic sensitivities, specificities, positive and negative predictive values was undertaken, inclusive of a latent class analysis (LCA) with a LCA-model estimate of prevalence by each school. The latter ranged from 9.6% to 100.0%, and prevalence by school for each diagnostic test followed a static ascending order or monotonic series of Kato-Katz, urine-CCA dipstick, DNA-TaqMan® and SEA-ELISA. We confirm that Kato-Katz remains a satisfactory diagnostic standalone in high-transmission settings but in low-transmission settings should be augmented or replaced by urine-CCA dipsticks. DNA-TaqMan® appears suitable in both endemic settings though is only implementable if resources permit. In low-transmission settings, SEA-ELISA remains the method of choice to evidence an absence infection. We discuss the pros and cons of each method concluding that future surveillance of intestinal schistosomiasis would benefit from a flexible, context-specific approach both in choice and application of each diagnostic method, rather than a single one-size fits all approach.

Objective: We aimed to assess the health impact of a national control programme targeting schistosomiasis and intestinal nematodes in Uganda, which has provided population-based anthelmintic chemotherapy since 2003., Methods: We conducted longitudinal surveys on infection status, haemoglobin concentration and clinical morbidity in 1871 randomly selected schoolchildren from 37 schools in eight districts across Uganda at three time points - before chemotherapy and after one year and two years of annual mass chemotherapy., Findings: Mass treatment with praziquantel and albendazole led to a significant decrease in the intensity of Schistosoma mansoni - 70% (95% confidence interval (CI): 66-73%) after one year and 82% (95% CI: 80-85%) after two years of treatment. Intensity of hookworm infection also decreased (75% and 93%; unadjusted). There was a significant increase in haemoglobin concentration after one (0.135 g/dL (95% CI: 0.126-0.144)) and two years (0.303 g/dL (95% CI: 0.293-0.312)) of treatment, and a significant decrease in signs of early clinical morbidity. The impact of intervention on S. mansoni prevalence and intensity was similar to that predicted by mathematical models of the impact of chemotherapy on human schistosomiasis. Improvements in haemoglobin concentration were greatest among children who were anaemic or harbouring heavy S. mansoni infection at baseline., Conclusion: Anthelmintic treatment delivered as part of a national helminth control programme can decrease infection and morbidity among schoolchildren and improve haemoglobin concentration.

The potential relationship between Schistosoma mansoni and anemia was examined using data obtained by the Schistosomiasis Control Initiative (SCI) before (baseline) and 1 year after (follow-up) a chemotherapeutic treatment program in Uganda. Changes in hemoglobin (Hb) levels in 2,788 children in relation to their schistosomiasis and/or hookworm infection intensity category and baseline anemia status were analyzed. At baseline, significant predictors of childhood anemia were intensities of S. mansoni and hookworm infection. At follow-up, moderate or heavy hookworm as well as heavy S. mansoni infections were important. Children heavily infected with S. mansoni or hookworm had significantly lower Hb counts at baseline compared with those not infected. Among anemic children at the baseline survey, a significant increase in Hb counts of 0.834 g/dL after treatment was found. Our results suggest that anemia is associated with schistosomiasis and hookworm in Ugandan children and that such anemia shows a significant improvement after chemotherapy.