Relative share of asymptomatic forms of hepatitis a in Plovdiv region, Bulgaria

To study the relative share of asymptomatic forms of Hepatitis A in family reservoirs of infection with different hygienic conditions.

Asymptomatic forms were identified by detecting anti-HAV IgM using ELISA. Two types of households: with poor hygiene and with good hygiene, were studied. The study was designed as case-control. A group of Hepatitis A contact children attending day nurseries and kindergartens was also included in the study.

The relative share of asymptomatic forms of HAV infection in poor hygiene households was 58.62%, while in those with good hygiene it was 41.57%. The comparison using Fisher's exact test yielded OR = 1.99 and 95% CI (P < 0.05). Asymptomatic forms were found in 7.75% of the investigated contacts among children attending day nurseries and kindergartens.

Asymptomatic forms of hepatitis A are very common which makes them epidemiologically quite significant as many of the cases remain unrecognized and later become focal points of new cases of the disease. Poor hygiene conditions are likely to cause more asymptomatic forms. The high relative share of asymptomatic forms found in the households supports the need for immunoprophylaxis of the contacts.