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Clustering prevalent among injection drug users with HCV in Vancouver
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One-third of people who inject drugs with hepatitis C virus infection from the Vancouver Injection Drug Users Study were found to be clustered, a phenomenon that is a risk factor for HCV transmission and associated with HCV seroconversion and HIV infection, according to data from a recent study.
“This study characterizes the molecular epidemiology of HCV among a cohort of [people who inject drugs] recruited between 1996 and 2012 in Vancouver, Canada,” the researchers wrote. “These findings could be used to better design and target public health and treatment strategies towards groups at higher risk of HCV transmission among [people who inject drugs].”
Data from 655 people who inject drugs with HCV sequencing (mean age, 36 years) from the Vancouver study were analyzed by researchers who used ClusterPicker to determine any evidence of clustering. The HCV genotypes prevalent among the participants were: genotype 1a (n=313), genotype 1b (n=41), genotype 2a (n=20), genotype 2b (n=46), genotype 3a (n=213), genotype 4a (n=4), genotype 6a (n=8), genotype 6e (n=1) and unclassifiable (n=9).
ClusterPicker analysis found 156 of 501 patients with HCV genotypes 1a and 3a in a pair (n=88) or cluster (n=68). Twenty-nine percent (n=91) of patients with HCV genotype 1a were grouped in 30 pairs (n=60) or seven clusters (n=31). Thirty-four percent (n=65) of patients with HCV genotype 3a were grouped in 14 pairs (n=28) or 10 clusters (n=37). Most of the clusters found were from participants with HCV at enrollment, however, 13 clusters had at least one group member with HCV seroconversion.
Logistic regression analysis further showed that age younger than 40 years, HIV infection, HCV seroconversion and syringe borrowing in the previous 6 months were independently associated with clustering.
“Phylogenetic clustering was common in this cohort of [people who inject drugs] in Vancouver and was independently associated with recent HCV seroconversion, HIV confections, age <40 years and recent syringe borrowing,” the researchers wrote. “Future studies are needed in cohorts of other [people who inject drugs] internationally to determine whether these results are generalizable to other settings.”
Disclosure: See the study for a full list of relevant financial disclosures.