Hepatitis A outbreak investigation in Descalvado county, SP, September to November, 2008

Abstract

 Hepatitis A is a viral disease spread worldwide. Transmitted by fecal-oral   route and occurs mainly because of inadequate sanitary conditions. This   paper describes a Hepatitis A outbreak investigation in Descalvado county,   São Paulo, after five years without a case. Case-control study was conducted,   with 34 IgM anti-HAV positive cases and 38 IgM anti-HAV negative controls,   matched for age and exposure local, in order to identify risk factors and   exposure source. Serologic exams were performed by Center of Diagnostic   Laboratorial of São Carlos, using DiaSorin® commercial kits and Instituto   Adolfo Lutz using “in house” method PCR technique. Average age of the cases   was 6,5 years old, 55,9% were men, and presented symptoms as: jaundice   (70,6%); dark urine (70,6%); pale stools (52,9%); nausea (47,1%); fever   (44,1%); vomiting (44,1%); abdominal pain (29,4%) and 2 hospitalizations   (5,9%). The most significant risk factor was the previous contact with a HAV   patient: OR de 21,45; IC 95% e p< 0,001. Consumption of vegetables without   disinfections was a second relevant risk factor: OR de 4.7; IC 95% e p<0,001.   The outbreak occurred in two elementary schools, one private day nursery   and neighbors of primary case. five years without a case increased the   number of susceptible, making one case enough to cause an outbreak.   Educational measures, vaccine and immunoglobulin application controlled   the outbreak and prevented new cases.