Monitoring schistosomiasis risk in East China over space and time using a Bayesian hierarchical modeling approach.

Schistosomiasis remains a major public health problem and causes substantial economic impact in east China, particularly along the Yangtze River Basin. Disease forecasting and surveillance can assist in the development and implementation of more effective intervention measures to control disease. In this study, we applied a Bayesian hierarchical spatio-temporal model to describe trends in schistosomiasis risk in Anhui Province, China, using annual parasitological and environmental data for the period 1997-2010. A computationally efficient approach-Integrated Nested Laplace Approximation-was used for model inference. A zero-inflated, negative binomial model best described the spatio-temporal dynamics of schistosomiasis risk. It predicted that the disease risk would generally be low and stable except for some specific, local areas during the period 2011-2014. High-risk counties were identified in the forecasting maps: three in which the risk remained high, and two in which risk would become high. The results indicated that schistosomiasis risk has been reduced to consistently low levels throughout much of this region of China; however, some counties were identified in which progress in schistosomiasis control was less than satisfactory. Whilst maintaining overall control, specific interventions in the future should focus on these refractive counties as part of a strategy to eliminate schistosomiasis from this region.

Concentration time course of praziquantel in Filipinos with mild Schistosoma japonicum infection.

Despite extensive use of praziquantel, the current drug of choice for the treatment of schistosomiasis and other helminthic infections, little information is available about its pharmacokinetics in individuals living in geographic areas where such infections are endemic. We investigated the pharmacokinetics of praziquantel by determining its serum concentration-time course in four selected Filipino volunteers with mild Schistosoma japonicum infection who lived in an endemic area in the Southern Philippines. At specified intervals during a 24-hour time period after a single oral dose of praziquantel (25 mg/kg BW), intravenous samples of blood were drawn, processed and analyzed for praziquantel using reverse phase high pressure liquid chromatography. The same study was repeated one week later to assess pharmacokinetic reproducibility. A third study, simulating current field practice, consisted of dosing the patient four hours apart and analyzing for praziquantel in serial blood samples drawn at specified time intervals after the first and second dose. The following results were obtained: 1) Serum concentration-time course of praziquantel was reproducible for each patient but varied from patient to patient. 2) Praziquantel was rapidly absorbed in the gastrointestinal tract as measurable amounts appeared in the blood as early as 15 minutes after dosing. Time to peak serum concentration ranged from 1.50 to 6.00 hours with almost complete elimination from blood by 24 hours whether it was administered as a single dose (1 x 25 mg/kg BW) or as a twice a day dose (2 x 25 mg/kg BW) 4 hours apart. Half-life values ranged from 1.00 to 2.50 hours.(ABSTRACT TRUNCATED AT 250 WORDS)