[Epidemiological surveillance of cystic echinococcosis in dogs, sheep farms and humans in the Rio Negro Province].

The surveillance of infection for Echinococcus granulosus in the Province of Rio Negro during 1980-2002 included serological and ultrasonographic screening in humans and arecoline test in dogs. In lieu of the limitations of the arecoline test the proposal was to supplant that test for the copro ELISA-copro/Western Blot complex applied to feces collected from the environment. The objective was to compare the pros and cons of the two tests and to evaluate the human and the canine infection prevalence. The working area encompassed 7 Departments with systematic canine parasiticide activities (Program Area) and 4 Departments, not endemic, as Control Area. The arecoline test was applied to the dogs in assembled groups with the voluntary participation of their owners (not randomized sampling). Samples for the detection of coproantigens were obtained from sheep farms selected at random and analyzed by the complex copro-ELISA /Western Blot. Prevalence in man was determined by screening the school population (6 to 14 years old) by ultrasound, and by means of the compulsory notification of cases from the official system. Dogs (416) were tested with arecoline, 365 of which belonged to the Program Area. Of these 19 (5.2%) resulted positive, while none of 51 dogs from the Control Area were positive. Samples (748) of feces were tested to detect coproantigens, obtaining 37 positive samples within the Program Area and 4 within the Control Area. Farms (271) from the livestock estate unit were evaluated, out of which 236 belonged to the Program Area, gave 32 (13.6%) positive results, while 4 (11.4%) of 35 from the Control Area resulted positive. Sonography tests (7421) were done in the Program Area detecting 40 (0.5%) carriers, while in the Control Area, over 1732 tests, 9 (0.5%) resulted positive. The arecoline test provides information about the dog prevalence while the detection of coproantigens in feces collected from the environment allowed to enhance the quality of the information, and the identification of environments where specific control activities focusing on risk must be concentrated. Also the study allowed to recognize new transmission areas.