Hepatitis A virus identification in an outbreak by enzymatic amplification.

From April 28th to May 22nd, 1987, the Medical Authority identified 13 cases (6 symptomatic cases) of hepatitis A (HA) in a school and in a college of Rome. The principal risk factor was determined to be "full-time presence at the State school and boarders at the college". The distribution of HA cases suggested a person to person contact; anti-hepatitis A virus IgM were identified in 12 out of 13 cases with high levels of transaminases. During the disease epidemic, water samples were taken from the well of the college for bacteriological and virological analyses. The water was classified as undrinkable due to the presence of 16 total coliforms/100 ml and 35 total bacteria count at 36 degrees C. Fecal coliforms, fecal streptococci and sulfite reducing clostridia were absent. Two water samples of 100 liters were collected and concentrated by adsorption-elution method on electropositive membranes or by ultrafiltration using a Millipore apparatus. Infectious Hepatitis A virus was only isolated from samples concentrated by adsorption-elution method on electropositive membranes using tissue culture methods and subsequently HA virus was identified by other traditional methods (Elisa and immunofluorescence). In contrast, PCR test performed on the concentrated samples, was positive only for the ultraconcentrated sample. The positivity of the PCR test confirmed the presence of the Hepatitis A virus in the well water.