Sexual-related Outbreaks of Acute HCV Infection  in HIV Positive Gay Men 

By Marina Nunez, MD, PhD

Two oral presentations at the 13^th CROI in Denver dealt with HCV outbreaks among HIV-infected homosexuals, a phenomenon that has been repeatedly reported for the past few years. A series from London included 111 cases of acute hepatitis C detected among HIV-infected individuals since 2000 [1].

All occurred among men involved in homosexual practices, and most of them were receiving HAART (65%) at the time of acute HCV infection. HCV-1, HCV-3, and HCV-4 genotypes accounted for 88%, 8%, and 4% of cases, respectively.

A molecular epidemiology study performed in 80 patients, using phylogenetic analyses of the HCV genome (91 E1/E2 sequences) identified multiple clusters. The biggest one involved 43 cases infected by the same genotype 1a virus. Provisional population dynamic analysis of this clade suggests that there has been an increasing transmission rate over time.

A questionnaire-based case-control analysis was performed to investigate factors present within the previous 12 months which might be associated with acute HCV infection. Multivariate analysis identified group sex practices as the only independent risk factor for developing acute HCV, with a 9-fold increased risk with two practices and 23-fold increased risk with more than two (p<0.001).

High-risk and traumatic sexual practices, often combined with drugs, are fuelling sexual transmission of HCV in this setting. These factors should be addressed through public health educational interventions.

The second report on acute HCV came from The Netherlands [2]. The researchers retrospectively tested 1,836 homosexuals, both HIV-positive and HIV-negative, participating in the Amsterdam Cohort Study (1985-2003). In addition, from 2003 to 2005, serum samples from individuals who had been diagnosed with acute HCV infection from hospitals in Amsterdam were obtained.

HCV prevalence at cohort entry was 1.3% (26). Since 2000, 29 cases of acute hepatitis C were identified (all but 1 case were found among HIV-positive men), with the highest incidence corresponding to most recent years. Thus a 10-fold increased incidence after 2000 compared to that 15 years before was observed in the HIV-infected group (0.87/100 person-years versus 0.08/100 person-years; p=0.001).

The most frequent HCV genotype was HCV-4 followed by HCV-1. Phylogenetic trees were constructed identifying two large clusters, one with 14 cases (HCV-4) and another with 7 cases (HCV-1a), and two smaller clades, with 2 cases each, of HCV-1a and HCV-1b infections. Interestingly, the HCV lineages involved in these clusters did not resemble isolates from intravenous drug users in Amsterdam, suggesting that these outbreaks have started by the introduction among homosexual men of different co-circulating HCV lineages.

Traumatic sexual activities or coinfection with mucosa-damaging sexual transmission diseases (syphilis, HSV-2, or lymphogranuloma venereum) within the period of HCV seroconversion were present in the majority of cases.

In conclusion, these data add more evidence to the finding of sexual transmission of HCV among homosexual men caused by mucosal trauma derived from aggressive sexual activities and concurrent sexual transmission diseases. Unique HCV-4 and HCV-1a strains circulate among heomosexual men in Amsterdam.

02/24/06

References

1.  M Danta and others. 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, CO. Abstract 86.

2. R Coutinho and T van de Laar. Rise in HCV incidence in HIV-infected men who have sex with men in Amsterdam: sexual transmission of difficult-to-treat HCV genotypes 1 and 4. 13th Conference on Retroviruses and Opportunistic Infections. 5-8 February 2006, Denver, CO. Abstract 87.