Social networks facilitate the transmission of hepatitis C virus (HCV) in people who inject drugs (PWID). The aim of this study was to assess how certain network structural characteristics are related to HCV infections in PWID and to determine the most susceptible individuals for HCV transmission in a network of PWID. PWID (N = 80) from central China were recruited from a previous follow-up case-control study. Demographic and behavioural information was obtained from a computerized database for each group. HCV RNA was extracted from blood specimens. Sequences were used to construct a phylogenetic tree and to determine genetic distances. Socio-metric social links were established between participants. Network measures were calculated using UCINET. Three HCV genotypes were identified, covering five subtypes. The density of the social networks for the whole sample (N = 80), case group (n = 31) and control group (n = 49) was 0.038, 0.054 and 0.008, respectively. PWID infected with HCV were in frequent contact with others within their group. There were four pairs of nodes with genotypic distances of 0.000 that were identified and clustered in subtypes 6a and 1b; each subject pair was linked and found in one clique. Three of the five most active nodes were infected with HCV. These three nodes served as a bridge, contributing to the connection of other nodes. These findings identify susceptible individuals for HCV transmission in PWID based on their frequent contact with others in the network. These results provide data that could be used for modelling HCV transmission patterns and in public health policies.

Hepatitis C virus (HCV) infection is associated with oxidative stress and vitamin A possesses antioxidant activity. The objective of the present study was to investigate vitamin A nutritional status in chronic hepatitis, liver cirrhosis and hepatocellular carcinoma (HCC), according to biochemical, functional and dietetic indicators correlating these findings with liver function, liver damage and death. Vitamin A nutritional status was analysed by serum retinol levels, dietetic indicators and functional indicators. A total of 140 patients with HCV-related liver disease were enrolled. Vitamin A deficiency was detected in 54·3 % of all patients, and there was a progressive drop in serum retinol levels from chronic hepatitis C patients towards cirrhosis and HCC patients. Increased total bilirubin, liver transaminases and prothrombin time, presence of hepatic encephalopathy and ascites were related to reduced serum retinol levels, and values ≤ 0·78 μmol/l of serum retinol were associated with liver-related death. A high prevalence of inadequate intake of vitamin A was observed in all stages of chronic liver disease. The functional indicator was not an adequate parameter for evaluating the vitamin A nutritional status. Therefore, serum retinol concentration is related to severity of the disease, liver complications and mortality. The effectiveness of nutritional counselling and measures of intervention in this group in improving vitamin A nutritional status should be examined further in a controlled study.