RISK-FACTORS ASSOCIATED WITH HUMAN CYSTIC ECHINOCOCCOSIS IN FLORIDA, URUGUAY - RESULTS OF A MASS-SCREENING STUDY USING ULTRASOUND AND SEROLOGY

Sonographic evidence of asymptomatic Echinococcus granulosus lesions i n the liver was found in 156 of 9,515 persons in the Department of Flo rida, Uruguay. The sensitivity of ELISA and latex agglutination serolo gy compared with ultrasound was 47.6% and 28.1%, respectively, and spe cificity was > 85%. There was a significant positive association betwe en positive sonography and a personal history of previous but treated Echinococcus infection while those that were seropositive but ultrasou nd-negative were significantly more likely to have a personal history of infection or a history of infection in their family. Prevalence of infection increased significantly with age. There was no correlation b etween echinococcosis and dog ownership or home slaughter of sheep but offal disposal was important, with an increased prevalence of infecti on of 3.2%, 2.8%, and 3.1%, respectively, in persons feeding offal to dogs or burying or burning it compared with a prevalence of 0.8-1.5% i n those using other methods of disposal. Almost half the population, w hen questioned, seemed to have sound knowledge about E. granulosus and described correct treatment of E. granulosus in dogs but this did not affect prevalence. There was a significant positive association betwe en infection and the presence of a fenced fruit/vegetable garden and u se of rural waters, particularly the cachimba (a small dam) and the al jibe (a cistern or tank) that collect rainwater from the ground surfac e and roofs, respectively.