[Epidemiology of hepatitis A in Sardinia: prevalence of anti-HAV in a sample of workers required to obtain health certificates].

The prevalence of Hepatitis A in South-Sardinia was determined in two samples of students in 1987 and 1988. In this paper we present the results of a seroepidemiologic survey covering a population of workers who were residents of the city of Cagliari or its suburbs. A sample of 299 workers was randomly drawn from a population of workers who went to the public health office to ask for a certificate of good health. A radioimmunoassay test (ABBOTT) was used for detection of anti-HAV. The analysis has been carried out in accordance with the manufacturer's instructions. We also study a sample of 323 students 14-19 years old. The age-specific prevalence was analyzed using an exponential model. The age is denoted by the variable x. The parameter h is the force of infection, the per capita rate at which susceptibles individuals acquire infection. If we take the force of infection as a constant, the fraction y of susceptibles in a population is y = exp (-h x) The anti-HAV prevalente increase with age: in workers 14-19 years of age 44 percent of the tested individuals were antibody positive. The prevalence was 82.7 percent in the population 25-29 years old. Finally we found a nearly total exposure to HAV in persons over 30 years of age. The workers 14-19 years of age showed a higher prevalence than the students did; the difference was statistically significant. The prevalence that we have observed in our study population is lower the one observed in the city of Sassari (North-Sardinia) in 1981. The siero-epidemiological pattern is similar to that prevailing in Greece and France (1979), in Umbria (1978), in the city of Milan (1973). The prevalence was, on the contrary, higher than that observed in North European Countries (1979) and in Venetia (1987). The data from the study population can be fitted satisfactorily with the exponential model (R2 = 0.994). So we can take the force of infection (h = -0.118, se = 0.005 as a constant.(ABSTRACT TRUNCATED AT 250 WORDS)