Sexual transmission of hepatitis C in HIV-positive men in the UK

It was important to see that sexually transmitted hepatitis C (HCV) infection, recently reported in almost 240 HIV-positive gay men in London and Brighton, was included as an oral presentation at the Retrovirus conference.

Mark Danta presented collective results from the HIV clinics at the Royal Free, Chelsea and Westminster and Brighton Hospitals, to better characterise this epidemic, which has been reported in the UK, but not so far been seen in other European countries. [1]

The researchers identified 111 HIV-positive gay men who were diagnosed with acute HCV (defined as anti-HCV antibody within 6 months of a negative test, or positive PCR) between October 2002 and August 2005. Mean age was 35 years. Mean CD4 was 552 cells/mm³ and 65% of patients were on HAART. HCV genotype was the most common (88%) with far fewer patients diagnosed with either genotype 3a (8%) or genotype 4 (4%). Although 17% vs 6% in the cases vs control had used IV drugs over the preceding 12 months, this did not explain the large majority of transmissions.

Phylogenetic trees were constructed from the 91 amplified sequences of the E1/E2 region of the HCV genome, comparing them with unrelated E1/E2 sequences, which revealed several independent lineages (the largest involving 43 patients).

A questionnaire-based case-control study was used to determine transmission factors using HIV mono-infected controls from each clinics database, matching for age, race, length of HIV infection, and HAART.

Cases (n = 60) had more sexual partners than controls (n = 130, median number of partners 30 vs 10, p <0.001) in the preceding 12 months, and more likely to meet in sauna or sex club (P=0.01) and seven times more likely to use the internet as first point of contact (p=0.003). Factors identified more commonly in cases than controls were: unprotected receptive and insertive anal intercourse (p <0.001), mucosally traumatic practices including fisting (p <0.001) and use of sex toys (p <0.001), group sex (88% vs 64%, p <0.001), and sexual activity under the influence of drugs (92% vs 62%, p <0.001), but not use of alcohol or heroin. 80% of cases vs 50% of controls shared nasal drug administration

In a multivariate analysis, group sex (in group of >2 individuals) was the only independent association. Odds ratios of 9.16 [95% CI 3.51-23.90] and 23.50 [9.47-58.33] were associated with participating in group sex on two, or three or more, occasions respectively.

The study concluded that high-risk and mucosally traumatic sexual factors are significantly associated with the recent transmission of HCV, and that the co-circulating HCV lineages identified by phylogenetic analysis belong to different subtypes and genotypes, indicating that the epidemic is not caused by viral genetic change, but rather patient factors such as sexual or drug behavior.

Comment

This data should already be well known to UK clinicians, as similar presentations have been presented at earlier meeting, including BHIVA. HCV is still less transmissible than HIV and requires identifiable high risk practices which can be targeted for education-based public health interventions.

Danta M, Brown D, Dusheiko G et al. Evidence for sexual transmission of HCV in recent epidemic in HIV-infected men in the UK. 13th Conference on Retroviruses and Opportunistic Infections, 5-8 February 2006, Denver, Colorado. Abstract 86.