Liver morbidity due to Schistosoma mekongi in Cambodia after seven rounds of mass drug administration

Severe liver disease due to Schistosoma mekongi was frequent in northern Cambodia. Between 1995 and 2002, seven rounds of mass chemotherapy (praziquantel) reduced infection from 50% to below 3%. In 2002, we assessed hepatosplenic morbidity by historical, clinical and ultrasonographic investigations in adults (older than 14 years) from endemic (n = 342) and non-endemic (n = 103) areas (Kratie province). Clinical hepatomegaly (25 vs. 0%), splenomegaly (55 vs. 0%), reported blood in stool (41 vs. 20%) and abdominal pain (78 vs. 57%) were significantly higher in the endemic area. In this area, significantly more subjects reported a family history of death due to schistosomiasis (12 vs. 0%); 63% (vs. 0%) reported having at least three treatments of praziquantel in previous years; and only 11% (vs. 99%) had normal liver ultrasonographic examination. Periportal fibrosis with portal hypertension was diagnosed in 46% (vs. 0%) of people in this area; 18% (vs. 0%) and 5% (vs. 0%) of portal hypertension was classified as moderate and severe, respectively. People aged between 24 and 35 years were mostly affected. There was no gender difference. The pathology in the endemic district is most probably residual morbidity of S. mekongi infections. Contributions of co-infections (hepatitis) cannot be excluded. Careful monitoring of the affected communities is required.