Intra-household clustering of hepatitis C virus infection in Karachi, Pakistan.

Transmission rates of hepatitis C virus (HCV) infection through non-sexual household contacts have been considered to be very low. This study evaluated intra-household clustering of cases of HCV infection in a low socio-economic community in Karachi, Pakistan. Serum samples from 341 household contacts of 86 thalassaemic HCV-seropositive children were evaluated for antibodies to HCV using an ELISA. Spatial analysis of data was carried out to test for intra-household clustering. Seventy of 341 (20.5%) household contacts were HCV-seropositive. Of the households studied, 44.2% (38/86) had one or more contacts who tested HCV-seropositive. Ecological analysis of variables at household level showed that in households where HCV-seropositive index thalassaemic children were male HCV tended to be transmitted to one or more familial contacts. Spatial analysis with an asymptotic score test of the null hypothesis of no extra within-family infectivity revealed that there was a significant tendency of HCV infection to cluster within a household (score statistic = 19.44, P=0.032). The results showed that non-sexual household exposure may play a role in efficient HCV spread to household contacts of HCV-infected persons and needs further evaluation.