RISK OF HEPATITIS-C VIRUS-INFECTIONS THROUGH HOUSEHOLD CONTACT WITH CHRONIC CARRIERS - ANALYSIS OF NUCLEOTIDE-SEQUENCES

We evaluated the risk of hepatitis C virus transmission through househ old contact with chronic carriers using nucleotide sequence analysis. Chronic hepatitis C patients (76 patients) were divided into two group s: familial transmission of hepatitis C virus was studied in group A ( 53 patients); group B (23 patients) served as nonfamilial controls for group A. Of 88 family members of group A patients, 18 (20%) had eleva ted serum ALT levels, 20 (23%) had antibodies against hepatitis C viru s and 16 (18%) had hepatitis C virus RNA in serum. Nucleotide sequence s of the region of the hepatitis C virus genome spanning the core and envelope genes were compared among the three groups. In group B, the a verage nucleotide sequence homology was 91.0% +/- 2.29% (a pairwise co mparison was made for each of the patients; n = 253). Isolates from tw o family members were significantly more homologous to isolates from c orresponding patients in group A than to isolates from group B patient s. Of the two isolates from family members, one was from a child whose mother was a patient (97.7% homology) and one was from a spouse (98.1 % homology). These results strongly suggest familial transmission of t he same hepatitis C virus strain. Further studies are necessary to elu cidate the route of intrafamilial transmission.