Cost-effectiveness analysis of the impacts on infection and morbidity attributable to three chemotherapy schemes against Schistosoma japonicum in hyperendemic areas of the Dongting Lake region, China.

A study was carried out in 8 villages endemic with S. japonicum in Hunan Province, China from 1998 to 2000 to evaluate the cost-effectiveness in preventing schistosome infection and related morbidity under three chemotherapy schemes: (1) 'clue' chemotherapy, consisting of treatment to those with contact with infected water and/or symptoms of infection; (2) 'mass' chemotherapy-treatment to all the villagers except those not able to take praziquantel; and (3) 'screen' chemotherapy-treatment prescribed to the stool egg positive cases after Kato-Katz examination. An itemized cost menu was used to estimate the cost incurred to each scheme, from the perspective of the health care provider. The numbers of cases prevented by chemotherapy schemes were estimated through standardized attributable fractions of the outcomes to absence of chemotherapy before intervention. The cost-effectiveness ratios were calculated using weighted ranks of unit costs of the four outcome measurements: the costs per case with infection, liver and spleen abnormality (as determined by ultrasonography) prevented and 1% reduction in intensity of infection (as estimated by egg per gram feces, EPG) after the two years of intervention. Sensitivity of total cost to changes in the costs of personnel, praziquantel and other key factors were analyzed. It is demonstrated that all the three schemes had a significant impacts on the prevalence and intensity of infection, but the overall effects on liver and spleen morbidity of the residents varied between schemes. Mass chemotherapy achieved the best cost-effectiveness ratio, with unit costs of preventing cases of infection, liver and spleen abnormality and 1% reduction of EPG being RMB yuan 161.2, 99.8, 219.3 and 176.3, respectively. However, clue and screen chemotherapy schemes did not show significant prevention of liver damages in the villagers. The unit costs per case prevented for the outcomes were RMB yuan 140.2, 602.7 and 169.3, respectively for clue chemotherapy, while RMB yuan 190.0, 448.4 and 145.0 respectively for screen chemotherapy. The study concluded that mass chemotherapy should still be the choice of preference in areas where prevalence of infection and frequencies of contact with infested water by residents are high, particularly if the drug cost could be further reduced. Clue chemotherapy could be an alternative to mass chemotherapy, especially when the frequency of water contact is not as high as 80% recorded in our study. Screen chemotherapy is the least favored option in the hyperendemic area of Hunan Province.

Analysis of social factors and human behavior attributed to family distribution of schistosomiasis japonica cases.

An investigation of family distribution patterns of schistosomiasis japonica was carried out in four pilot villages in Yunnan Province. Family clustering of the disease was present in Bihuayuan Village before and after economic reform (site A); however, such clustering did not occur in Tuanshan and Liantie Villages (sites B and C) in the same periods. Being contrary to the stage prior to economic reform family clustering existed in Zhonghe Village (site D) after the reform. The results obtained from single- and multifactor analysis showed that the main human behavior related to family distribution of schistosomiasis in mountainous regions of Yunnan Province included the frequency of laborer migration, contact with cercariae-infested water in public places or family microenvironments with a high transmission potential, promiscuous defecation and status of cattle grazing. The frequency of laborer migration and human contact with cercariae-infested water in public places in sites B and C without family clustering was higher than that in sites A and D with family clustering. Place for promiscuous defecation and cattle grazing in site A converged compared with that in sites B and C.