Intrafamilial transmission of hepatitis C virus: a systematic review

To examine the risk of hepatitis C virus (HCV) transmission between patient s infected with HCV and their household members (siblings, offspring and pa rents), as well as their stable heterosexual partners, a systematic search of the MEDLINE database was undertaken for all relevant articles published up to June 1997. English language publications or those supplemented with a n English abstract that reported studies concerning hepatitis C, and househ old, intrafamilial, sexual and intraspousal transmission of HCV, were revie wed. Data from uncontrolled and controlled studies were collected and analy sed separately. Studies reporting the exclusive use of first-generation ant i-HCV antibodies without supplemental tests were excluded. Pre- or postnata l mother-to-child transmission of HCV and homosexual and heterosexual trans mission of HCV among non-permanent couples were not included. Unweighted da ta from individual studies were pooled for each category of family member. Data were also analysed separately for Japanese and non-Japanese studies be cause there is evidence that intrafamilial transmission may differ, based o n endemicity of the viral infection. Comparisons were drawn only from contr olled studies that reported the prevalence of HCV in family members of both HCV-positive and HCV-negative controls. Pooled odds ratios (OR) and 95% co nfidence intervals (CI) were calculated for each family category. In uncont rolled studies, the pooled prevalence of anti-HCV among 4250 stable sexual contacts of patients with HCV-related chronic liver disease (CLD) was 13.48 %, while the pooled prevalence of anti-HCV among 580 stable sexual contacts of patients who contracted HCV as a result of multiple transfusions was 2. 41%. In controlled studies, the pooled prevalence of anti-HCV among 175 sib lings and household contacts of patients with CLD was 4.0% compared with 0% among 109 contacts of anti-HCV-negative controls (OR 9.75, 95% CI 0.91 ad infinitum). The pooled prevalence of anti-HCV among offspring of Japanese H CV-infected CLD patients was 17% compared with 10.4% among offspring of HCV -negative Japanese controls (OR 1.77, 95% CI 1.21-2.58, P=0.002). The poole d prevalence of anti-HCV among spouses of non-Japanese HCV-infected CLD pat ients was 15.2% compared with 0.9% in the spouses of non-Japanese HCV-negat ive controls (OR 20.57, 95% CI 6.05-84.08, P=0.0001). The prevalence of ant i-HCV among non-Japanese offspring and Japanese spouses of HCV-infected pat ients was not increased compared with controls. HCV genotype homology and m utant analysis studies in pairs of HCV-infected patients and their HCV-infe cted contacts showed that concordant genotype homology was found in 66% of non-sexual contacts and in 74% of sexual contacts. Sequence homology of gre ater than 92% was found in 19 out of 35 pairs. Hence, evidence exists that familial, non-sexual and sexual transmission of HCV does occur. In Japanese patients, transmission probably occurs in younger family members while, in non-Japanese patients, transmission probably occurs at an older age, after contact with an HCV-infected spouse.