Echotomographic and serological population-based study of hydatidosis in central Tunisia.

A population-based echotomographic (ECT) and serological survey of hydatidosis was carried out in a high risk community located in Central Tunisia. 1434 subjects over 5 years of age (93.3% of the population in this age range) underwent an abdominal echotomography (ECT) and a serological test (ELISA with confirmation by counterelectrophoresis). The ECT prevalence rate was 3.5% and increased with age reaching 7.7% in the over 39 years age group. Most subjects (96.0%) had liver cyst(s). The serological prevalence rate was 2.9%. A strong agreement was found between ECT and serological results (Kappa test = 0.449). Taking ECT as a reference, the relative specificity and sensitivity of serology were 99.3 and 62.0 respectively. Most ECT positive seronegative subjects had calcified cysts. These results confirm the presence of highly endemic foci of hydatidosis in Central Tunisia, show a good agreement between serological and ECT results at a population level and demonstrate the high feasibility of ECT as a screening technique.

Distribution of surgical hydatidosis in central Tunisia (1982-1985).

The mean annual surgical incidence rates (MASIR) of hydatidosis were measured for the 1982-1985 period in central Tunisia in order to investigate the natural history of human hydatidosis and provide baseline data for the evaluation of future prevention campaigns. 986 cases were identified from surgical records of regional hospitals to which cases from central Tunisia are mandatorily referred. The overall MASIR was 19.3 per 10(5) inhabitants. The MASIR according to district varied from 0 to 56.6 per 10(5), was higher in women than in men (22.6 versus 15.8 per 10(5] and increased with age (maximum 53.0 per 10(5) in the 50-59 age group for women and 27.1 per 10(5) in the 40-49 group for men). Among the 940 cases with single organ hydatidosis, liver ranged first (55.3%, 545/940), then lung (32.4% 320/940), kidney (2.7%) and spleen (1.8%). Among the 865 subjects with single lung or liver hydatidosis, liver was more often involved in women (349 out of 503) than in men (196 out of 362) (chi 2 = 20.9, p less than 0.001). In both sexes, the lung/liver ratio decreased with age. These data reveal the existence of highly endemic foci of hydatidosis within central Tunisia. The predominance of infection in women might be due to sex related behavioral differences. The causes of liver predominance in women and variation of lung/liver ratio are open to question.