A variety of factors related to sexual activity and drug use have contributed to an outbreak of hepatitis C among HIV-positive gay men in Southeast England in recent years, according to a presentation by Mark Danta from the Royal Free and University College Medical School at the American Association for the Study of Liver Diseases meeting in San Francisco on November 13.
More than 200 cases of acute hepatitis C virus infection have been diagnosed in HIV-positive gay men seen at the Royal Free Hospital, Chelsea and Westminster Hospital, and University College Hospital in London; an additional twelve cases have been detected in Brighton. AIDS Treatment Update published the first reports about this new sexually transmitted hepatitis C virus epidemic in 2002, and aidsmap has since reported on its developments.
The current study aimed to characterise the mode of hepatitis C transmission using both molecular analysis and a case-control examination of risk factors. The study included 111 HIV-positive gay men with acute hepatitis C recruited since 2002 from HIV units at Chelsea and Westminster (50 cases), Royal Free Hospital (50 cases), and Brighton Hospital (eleven cases). The median age was 36 years, 65% were on antiretroviral therapy, and the mean CD4 cell count at diagnosis was 552 cells/mm3. Most of the men (88%) had hepatitis C genotype 1, 8% had genotype 3, and 4% had genotype 4. About one-third (30%) had been diagnosed with syphilis within the year prior to contracting hepatitis C.
In the molecular analysis, the researchers constructed phylogenetic trees using the E1/E2 sequence of the hepatitis C virus genome to illustrate the relatedness between the men’s specific viral variants. The genome patterns clustered into several distinct monophyletic “clades,” or lineages, providing strong evidence for common sources of HCV transmission. Because the clusters crossed subtypes and genotypes, the analysis suggested that, “this epidemic is not due to a hepatitis C viral change, but rather behavioural and/or environmental factors,” Dr Danta reported.
In the epidemiological study, 60 patients with acute hepatitis C and 130 matched HIV-positive/hepatitis C virus-negative controls completed questionnaires about their risk factors over the twelve months preceding hepatitis C virus diagnosis. Baseline characteristics were similar in both groups, although the case patients were less likely than the controls to be on anti-HIV therapy.
In terms of risk factors, men with acute hepatitis C were more than twice as likely as control subjects to be injecting drug users (17% vs 7%; p = 0.08), although the overall rate was low compared to other hepatitis C virus-infected populations. Cases were also somewhat more likely to have tattoos (60% vs 44%); piercings (70% vs 52%; p = 0.03); and a history of blood transfusion (17% vs 8%). Because most tattooing and piercing was done under sterile conditions, however, Dr Danta suggested that hepatitis C infection was “not really attributable” to these factors.
Similar percentages of men in both groups met sex partners in bars or clubs, at private parties, or in public cruising areas. But men with acute hepatitis C were significantly more likely to meet partners in sex clubs/bathhouses/saunas (approximately 4% vs 1%; p = 0.01) or on the Internet (approximately 49% vs 8%; p = 0.003). The hepatitis C-infected men had a median 30 sex partners in the past year, compared with ten for controls (p = 0.001); in both groups, a majority of these partners were “one-night stands.”
Looking at specific sexual practices, hepatitis C-infected men were significantly more likely than control subjects to have engaged in unprotected receptive or insertive anal intercourse (p < 0.001), receptive or insertive fisting (p < 0.001), use of sex toys (p < 0.001), receptive or active analingus (“rimming”), S&M, and group sex; rates of protected receptive and insertive anal intercourse were similar in both groups. The largest difference was seen in the rates of insertive fisting (about three times higher among the hepatitis C - infected men) and receptive fisting (about four times higher).
Men with acute hepatitis C were significantly more likely to have ever had syphilis, gonorrhoea, and non-specific urethritis (all p < 0.01). But overall, most men in both groups had a history of any sexually transmitted infection: 92% for the hepatitis C-infected men and 78% for the control subjects (p < 0.01).
The hepatitis C-infected men were significantly more likely to have had sex under the influence of drugs (92% vs 62%; p < 0.001). Use of various “club drugs” including crystal methamphetamine, ketamine, GHB, and ecstasy was significantly more common among men with acute hepatitis C (p = 0.006 or less). While injecting drug use was uncommon in both groups, hepatitis C-infected men were significantly more likely to have shared paraphernalia for intranasal drug use (approximately 79% vs 49%; p < 0.001).
Summarizing these findings, Dr Danta concluded that various high-risk sexual practices, meeting partners online, the use of “club drugs,” and sharing equipment for intranasal drug use are all linked to hepatitis C transmission among HIV-positive gay men. However, because there is considerable overlap among these factors, it is difficult to tease out their relative contributions. Since high-risk sexual and drug use practices appear to be driving this epidemic – as opposed to traditional parenteral risk factors – he recommended that education about safe sex and drug-sharing practices should be the focus of preventive public health interventions.
Danta M. et al. Evidence for sexual transmission of HCV in recent epidemic in HIV-infected men in South-East England. 56th Annual Meeting of the American Association for the Study of Liver Diseases, San Francisco, abstract 67040, 2005.