Transmission of hepatitis A in hamburg, germany, 1998-1999--A prospective population based study.

To study the pattern of transmission of HAV in a large urban community a prospective cohort study was conducted in Hamburg between 1 January 1998 and 31 December 1999. Four hundred and eleven patients were classified as hepatitis A cases comprising 144 foreign and 267 German persons. Univariate analyses were carried out to examine differences between socio-demographic, clinical and behavioural characteristics. To determine independent predictors for HAV infection a multiple logistic-regression model was used. The principal risk factor was travel to areas where hepatitis A is endemic, with 32.6% (n= 134/411) of all documented cases of hepatitis A. Foreign patients who had acquired the infection abroad, mostly children, accounted for the majority of these cases. Of all 411 cases, 42 (10.2%) were associated with parenteral drug, followed by day-care or school contact (8.3%; n = 34). Outbreaks contributed to 11.4% of cases (n = 47), but only 7.1% (n = 29) were household contacts. The low incidence rate among exposed persons in the households of those infected was similar in the groups of foreign and German nationals (17/384 = 4.4% and 12/231 = 5.2%, respectively), which may demonstrate a good hygienic level in general. Our findings suggest that preventive measures such as the improvement of hygienic conditions in a defined general population may contribute to a reduced incidence of hepatitis A. Nevertheless, because hygienic standards may change with time, this policy should be supplemented by targeted vaccination of groups at risk.