[Outbreaks of hepatitis A in the City of Havana in the year 1991].

Fifty-six outbreaks of hepatitis A infection were studied in City of Havana between January and September, 1991. In 34 of these, the presence of the hepatitis A virus (HAV) was confirmed, either by the detection of specific serum IGM antibodies to the HAV or by the detection of the antigen in the feces of the subjects under study. Diagnosis was not made in some of the outbreaks due to the insufficient number of samples sent to the laboratory. Of the 453 blood serum samples under study, 126 were positive for IGM antibodies to HAV (27.8%): a there was a good correlation between the presence of this immunoglobulin and the levels attained by the alanyl aminotransferase enzyme (ALT). Only in 19 feces samples, of the 263 under study, was the HAV antigen detected, which accounted to 7.2%; it was demonstrated that this marker is not useful for the diagnosis of an outbreak of hepatitis A infection.