Study Confirms International Outbreak of Sexually Transmitted Hep C

Hepatitis C virus (HCV) can be spread in ways similar to HIV, particularly through sharing or receiving the following:

  • equipment for substance use
  • tattooing needles

  • contaminated blood or blood products

HCV infects the liver and can cause inflammation and liver damage. Over a period of many years, liver damage builds up and this organ becomes increasingly dysfunctional. Complications ensue, and in some cases liver cancer occurs. HIV infection appears to accelerate the course of HCV-related disease.

For the past two decades, HCV infection has mostly affected people who share needles to inject street drugs or who have received contaminated blood products, such as clotting factors, before routine testing for HCV was available. Now an international team of researchers has uncovered evidence that HCV has been transmitted sexually, in many cases among HIV positive people. The emergence of a previously unrecognized sexually transmitted germ is troubling and has implications for sexual health and disease prevention programs.

Study Details

Research teams pooled health-related information collected from 226 HIV positive men from the following countries:

  • Australia

  • France

  • Germany

  • Netherlands

  • United Kingdom

Most (96%) of these men had acute HCV infection diagnosed because of detectable antibodies to HCV and other specific blood tests, not because of any symptoms of HCV infection, as symptoms of this infection can be similar to those of other viral infections.

The average profile of the men in this study was as follows:

  • age: 38 years

  • CD4+ count: 518 cells

  • proportion taking HAART: 62%

  • proportion who injected street drugs: 14%

Researchers performed a molecular analysis of HCV from each of the participants to find out more about this virus.

Results -- Strains of HCV

HCV can be divided into several strains, or genotypes, called 1a, 2b and so on. Genotypes 1 and 4 tend to be more difficult to treat than genotypes 2 and 3. The most common genotype in this study was generally 1a. The exception was cases from France, where genotype 4d was more common.

The molecular analysis of HCV from participants found that 84% of them had HCV that was closely related to HCV found in another study participant. Moreover, this degree of commonality was seen across European countries in the study, suggesting that HCV had spread internationally.

Information collected from each country suggested that HCV was transmitted through unprotected anal sex that damaged the lining of the rectum. This can occur in several circumstances, including these:

  • having prolonged bouts of unprotected anal intercourse

  • having multiple episodes of unprotected anal sex

  • being fisted

  • having another sexually transmitted infection such as syphilis or LGV (lymphogranuloma venereum)

  • engaging in substance use

Substance use can have several consequences that may increase the risk of acquiring HCV and HIV, as follows:

  • weaken a person's sense of judgment and common sense

  • dull the perception of pain

  • dry out the mucous membranes

Indeed, data from other studies in the UK and Germany suggest that some men who became sexually infected with HCV had used cocaine and methamphetamine (crystal meth) before or during sex.

Damaged mucous membranes lining the rectum can bleed, facilitating the entry of germs such as HIV and HCV.

Concentrating Germs

Some men engage in sero-sorting -- the practice of having sex with other men of similar HIV status. For HIV positive men, sero-sorting removes the worry of infecting someone else with HIV. But it may also give some HIV positive men the false assurance that they may freely engage in unprotected intercourse without risk.

In reality, unprotected anal intercourse can pose the following risks for HIV positive men:

  • infection with or the transmission of HIV strains that are resistant to some therapies -- this can reduce a person's future treatment options

  • infection with or the transmission of potentially dangerous sexually transmitted infections (STIs) such as human papilloma virus (HPV; this can cause anal cancer), LGV and syphilis -- STIs can cause sores, lesions or otherwise inflame tissues, making the transmission of STIs (including HIV) more likely

  • In men co-infected with HIV and HCV, HCV is more often found in the semen compared with HCV positive men without HIV. The presence of HCV in the semen combined with a weakened immune system may partially explain the enhanced risk that HIV positive men have for HCV infection when they engage in unprotected sex.

So it is possible that STIs can be passed back and forth and can concentrate in sexual networks where unprotected anal intercourse takes place.

A Virus Becomes More Common

The international study team performed an evolutionary analysis of HCV found in the men and concluded that in the majority of cases (85%) this virus was transmitted after 1996. Indeed, in 63% of cases, HCV was transmitted after the year 2000. This evolutionary analysis led the researchers to conclude that between 1975 and 1996, HCV was transmitted only occasionally into the sexual networks of gay and bisexual men in this study. However, after 1996, transmission of this germ increased. This conclusion is supported by data from London and Amsterdam. There, HCV infection among gay and bisexual men was uncommon before the year 2000. After that year, cases increased by about 20 percent per year in London and by a factor of 10 in Amsterdam.

Why the Change?

Researchers are not certain about the reasons for the increase in HCV transmission, but they suspect that behavioural factors rather than a change in the nature of HCV are responsible for the increase in HCV. Here are the events that they describe that may explain the increased rate of sexually transmitted HCV in some gay/bisexual men:

  • The introduction of HAART in 1996 in high-income countries has been linked to a subsequent increase in unprotected sex and, consequently, STIs.

  • Unprotected anal intercourse among men with the same HIV serostatus (sero-sorting) may be seen as a "harm-reduction" strategy.

  • However, in this context, unprotected anal intercourse may place these men at increased risk for STIs, different strains of HIV and also HCV.

  • STIs can cause inflammation, sores and ulcers, which can help HCV gain entry to the body.

In a recent study, HIV positive men who engaged in behaviours such as unprotected anal intercourse, group sex, fisting and recreational drug use were more likely to have become infected with HCV compared to HIV positive men who did not do these things. The study team also noted that "organized sex parties have probably extended sexual networks and increased the connectivity of high-risk gay/bisexual communities in different parts of the world."

Australia -- a Warning Sign

In Australia the researchers noted that injection of street drugs accounted for a significant proportion of HCV infections in gay and bisexual men. They also noted that molecular analysis revealed that one Australian man had a strain of HCV that was circulating in Europe. This finding suggests that HCV has been transmitted between the two continents. What's more, the most common strain of HCV circulating among the men in this study does not respond well to therapy.

In an era of relatively inexpensive and frequent travel, at least in high-income countries, outbreaks of an STI on one continent can affect susceptible people in a distant region. This has been the case with HIV, antibiotic-resistant infections and, recently, LGV. Now it appears that the current outbreak of HCV in Western Europe among gay and bisexual men may also have this potential.

To prevent a more widespread outbreak of HCV among gay and bisexual communities, the study team recommends at least these steps:

  • Hepatitis prevention education should be made available to at-risk communities and to physicians who care for them.

  • All HIV positive gay and bisexual men should have annual tests for HCV infection.

  • HIV negative men who engage in high-risk activities (unprotected anal intercourse, group sex, recreational drug use, fisting, injection drug use) or who have been diagnosed with ulcers caused by STIs should consider more frequent testing for HCV and HIV.

Although this report focuses on research with gay and bisexual men, women who have unprotected anal intercourse or who engage in other high-risk activities are probably also at risk for sexually transmitted HCV.


We thank Martin Vogel, MD, from the University of Bonn, Germany, for his helpful comments, discussion and research assistance.


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