Hepatitis C virus infection in households of anti-HCV chronic carriers in Italy: a multicentre case-control study.

To test the hypothesis that households of anti-HCV positive subjects might be at increased risk of HCV infection, a case-control study was carried out comparing 518 family members of 205 anti-HCV positive subjects (index carriers) with 281 family members of 100 anti-HCV negative subjects (index controls), consecutively observed in ten gastroenterology units in different Italian regions. The index carriers were age and sex matched to the index controls and their households were similar with respect to the main sociodemographic characteristics. Anti-HCV antibodies were found in 6.9% (36/518) of household members of index carriers and in 3.2% (9/281) of household members of index controls (p < 0.05). The results of multiple logistic regression analysis showed that being over 50 years of age was the sole independent predictor for a household contact of the likelihood of being anti-HCV positive (O.R. 3.6; C.I. 95% = 1.5-8.2). Being in the household of an anti-HCV index carrier was marginally associated to anti-HCV positivity (O.R. 2.0; C.I. 95% = 0.9-4.6). No association was found for sex, area of residence, family size, lowest level of schooling, or any type of family relationship. These findings are not in compliance with the statement that household contacts of HCV carriers are at increased risk of HCV infection. The 3.2% anti-HCV prevalence rate observed among household contacts of anti-HCV negative index controls may suggest that the true anti-HCV prevalence in the general population in Italy is nearly 2.5 times as high as the 1.3% found in Italian blood donors.