Academic journal article Bulletin of the World Health Organization

Schistosomiasis Control in China: The Impact of a 10-Year World Bank Loan Project (1992-2001)/lutte Contre la Schistosomiase En Chine : Impact Du Projet De Pret De la Banque Mondiale Sur 10 Ans (1992-2001)/control De la Esquistosomiasis En China: Impacto De Un Proyecto De Prestamo del Banco Mundial a 10 Anos (1992-2001)

Academic journal article Bulletin of the World Health Organization

Schistosomiasis Control in China: The Impact of a 10-Year World Bank Loan Project (1992-2001)/lutte Contre la Schistosomiase En Chine : Impact Du Projet De Pret De la Banque Mondiale Sur 10 Ans (1992-2001)/control De la Esquistosomiasis En China: Impacto De Un Proyecto De Prestamo del Banco Mundial a 10 Anos (1992-2001)

Article excerpt

Introduction

Schistosomiasis caused by Schistosoma japonicum has long been a major public health problem in China. Sustained control efforts had reduced the number of infected people from 11.8 million in the 1950s (1) to 1.6 million in 1989 (2). Four out of 12 provinces had eliminated schistosomiasis by that year, but the disease was still endemic in 240 counties in eight provinces, and 44 million people were estimated to be at risk. Oncomelania snails were still present in numerous areas covering a total of 3.6 billion [m.sup.2], and the animal reservoir of S. japonicum--thought to play a major role in transmission--was still considerable. Approximately 0.2 million cattle and buffaloes were estimated to harbour the infection. Schistosomiasis control therefore faced a serious challenge at the end of the 20th century. There was a consistent gap between the available funding and the financial resources required to make further progress, in response to this situation, the Chinese Government obtained a long-term World Bank loan to boost schistosomiasis control.

The objective of The World Bank Loan Project (WBLP) for schistosomiasis control was to boost morbidity control according to the strategy recommended by the WHO (3, 4), while, at the same time acting on transmission with the ultimate goal of interrupting it. The main control tool was large-scale chemotherapy; this was complemented by health education, chemical control of snails and environmental modification where appropriate. The specific operational targets set were as follows:

* to reduce the prevalence of infection in humans by 40%;

* to reduce the prevalence of infection in cattle and buffaloes by 40%; and

* to reduce the snail infection rate and the density of infected snails by at least 50%.

Materials and methods

The project area covered eight provinces containing 219 counties in which schistosomiasis was still endemic in 1992. Three operational strata were defined on the basis of disease prevalence in humans as recorded during a nationwide epidemiological survey conducted in 1989 (2), and different control strategies were applied in each of these strata. Large-scale chemotherapy was the main control tool used to reinforce morbidity control in areas of high endemicity (i.e. prevalence > 15%) and medium endemicity (i.e. prevalence between 3% and 15%), whereas in areas of low endemicity (i.e. prevalence < 3%) the transmission control component was reinforced by environmental management. The technical approaches are described below.

Chemotherapy in human populations

In areas of high endemicity, all individuals between 6 and 60 years old were given yearly treatment. In areas of medium endemicity, half of the residents were screened by examination of a stool examination (using the Kato-Katz technique) or a serological test (enzyme-linked immunosorbent assay (ELISA), circumoval precipitin test or indirect haemagglutination test) every year (i.e. each person was tested every other year) and those with positive results were treated. In areas of low endemicity, all 7-14-year-old children were screened in the same way as in areas of medium endemicity every other year and treated if their results were positive. The treatment in all areas consisted of a single dose of praziquantel, at a dosage of 40mg/kg body weight.

Chemotherapy in livestock

In areas of high endemicity, all cattle and buffaloes were treated once a year without preliminary screening. In areas of medium endemicity, approximately one-third of cattle and buffaloes were treated once a year, primarily those that had been pastured on areas with transmission potential. In areas of low endemicity, cattle and buffaloes imported from other provinces in which schistosomiasis was endemic and those under 2 years of age pastured on snail-infested land were examined and treated with praziquantel if infected.

Snail surveillance and control

In areas of high endemicity of schistosomiasis, random snail surveys were carried out in approximately 40% of the snail infested areas each year. …

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