Epidemiological surveillance of human hydatidosis by means of ultrasonography: its contribution to the evaluation of control programs

Epidemiological surveillance for hydatidosis is based on initial determinat ion and follow-up of the infestation rate in man, sheep and dogs. The use o f ultrasonography (US) as a screening method has demonstrated its usefulnes s in detecting asymptomatic human carriers of abdominal hydatidosis. To eva luate the contribution of US to epidemiological surveillance within the fra mework of disease control programs, we performed 719 US studies in school c hildren from 7 to 13 years of age, in rural areas of Rio Negro, Argentina, subjected to canine deparasitization during 1984/1986 and 1997/1998. In the first period, 15/268 (5.6%), while in the second, 5/451 (1.1%) carriers we re detected (P < 0.0004). The average diameter of the cysts was 4.71 cm in 1984/1986 and 2.14 in 1997/1998. US as a mass screening method allows evalu ation of early changes in human prevalence rates, closely related to infest ation rates in sheeps and dogs, thus providing a sensitive indicator of the evaluation of control programs. (C) 2001 Elsevier Science B.V. All rights reserved.