31 May 2011 

German researchers dig deep to understand how hepatitis C virus is transmitted sexually

Before routine screening of the blood supply was implemented in Canada and other Western countries, hepatitis C virus (HCV) was transmitted through transfusion of contaminated blood and products made from blood, such as clotting factors.

Now, in high-income countries and regions such as Canada, Australia, the U.S. and Western Europe, HCV is most commonly transmitted by sharing contaminated equipment for substance use. Less common modes of transmission include sharing equipment used for tattooing and body piercing

Now, another route of transmission has been confirmed. An epidemic of sexually transmitted HCV is occurring across high-income countries among some gay and bisexual men, particularly those who are HIV positive and who do not inject illicit substances. According to an international team of researchers, this route of transmission appears to have begun in the mid-1990s. Furthermore, researchers in Canada, Australia and Western Europe have found that the spread of HCV co-infection among HIV-positive men appears to have accelerated after the year 2000.

Scientists at research centres in Berlin, Bonn and other German cities have collaborated to investigate the spread of HCV co-infection among gay men in that country. Their results suggest that “sexual practices leading to rectal bleeding, and snorting drugs [among people who have high rates of HCV infection] are risk factors for [the further spread of HCV].” Under such circumstances, condoms and gloves may not provide sufficient protection “if they are contaminated with blood,” noted the German team. Common sexually transmitted infections such as gonorrhea, syphilis and genital warts also play a role in helping HCV (and HIV) to spread.

Study details

Between 2006 and 2008, German researchers recruited gay men who were co-infected (“cases”) and others who were not co-infected with HCV and HIV (“controls”) to understand how HCV was being transmitted sexually. They also surveyed men in Germany about their knowledge, attitude and behaviours about sexually transmitted infections (STIs).

In total, the research team found 34 HCV/HIV co-infected men and 67 HIV-positive men who were not infected with HCV. All 101 men were of similar age, employment and relationship status and other characteristics, as the following average profile indicates:

  • age – 41 years
  • age at first sex with a man – 17 years
  • taking anti-HIV therapy – 77%
  • more than 97% of men self-identified as gay


The team collected a huge volume of data that provided clues about HCV transmission in sexual situations. Statistical analysis revealed that any of the following behaviours were linked to the transmission of HCV:

  • rectal trauma with bleeding
  • frequent receptive fisting without the use of gloves
  • group sex
  • nasally-administered drugs

The surgical connection

The study team found that many of the co-infected men had a history of multiple episodes of ano-rectal surgery and rectal bleeding during sex or the use of oral drugs for erectile dysfunction. Such medications allow prolonged bouts of sex.

The German researchers theorize that the high frequency of ano-rectal surgery was likely for the treatment of warts and other growths caused by the sexually transmitted virus HPV (human papilloma virus). Surgeries for ano-rectal warts can traumatize delicate mucosal tissue and can lead to bleeding after surgery. If insufficient time elapses between ano-rectal surgery and a resumption of anal intercourse, bleeding can occur, leading to transmission of HCV, HIV and other germs.

Serosorting or seroguessing?

One measure that some people take in an attempt to reduce the spread of HIV and other microbes is to restrict sexual activity to people of similar perceived HIV antibody status. This behaviour is called serosorting. In theory, serosorting should help reduce the transmission of microbes such as HIV. However, in reality, several factors can reduce the protection theoretically afforded by serosorting, such as these:

  • People may make assumptions about the serostatus of a potential sexual partner based on appearances, behaviour or speech. This is sometimes called sero-guessing and such guesses may not always be correct, as University of Windsor Professor Barry Adam has found in his research.
  • Many STIs can initially be symptom-free and occur inside delicate ano-genital tissue, so people may not be aware that they are infected. In the absence of frequent and extensive screening for STIs and other medical check-ups, sexual networks of serosorters run the risk of concentrating STIs within such networks. Moreover, as STIs can cause sores or lesions and inflame delicate ano-genital tissue, such infections raise the risk of HIV transmission.
  • Serosorters who focus only on preventing HIV transmission may inadvertently neglect to protect themselves from STIs.

Magnifying risk

The German researchers found that men in their study had many sexual partners and this increases the risk of exposure to HCV. Another factor not taken into account is that at room temperature HCV can be infectious for up to 16 hours. If sharing of equipment (such as straws to inhale drugs) or sex toys occurs, HCV can be transmitted.

Nasally administered drugs

Studies have found that some men who have sex with men (MSM) who participate in sex parties sometimes use drugs—amphetamines, cocaine, ketamine (Special K)—to enhance feelings of pleasure or to feel more energetic. These may be taken orally, rectally or by inhalation. The German team notes that equipment for intranasal use of these drugs is “often shared and may come into contact with mucosal secretions or blood from fellow users.” These drugs may themselves injure delicate mucous membranes in the nose and elsewhere, allowing the transfer of HCV and other germs from one person to another. Taking into account this and other information, the German team made this statement:

“A rolled banknote that is being circulated at a commercial sex party might be sufficient to expose consumers to HCV-contaminated blood.”


The German team summarized its findings with this statement:

“We suggest that blood rather than semen is the critical medium. An insertive partner’s fist (or penis), contaminated with blood, might serve as a vector for subsequent receptive partners in a group sex session, when condoms or gloves are either not applied or not changed for every new partner—particularly when using a collective supply of lubricant. Lesions in both the ano-rectal mucosa—from fisting, prolonged anal intercourse or rectal STIs—could serve both as a portal of entry and as a source of infection.”


The research team makes the case for educational efforts to help prevent the spread of HCV inside sexual networks of MSM.

Based on their research, the German team stated: “Sexual transmission of HCV seems to occur when HCV-contaminated blood is passed on in a context [where there is an increased risk for HCV transmission, such as group sex] in HIV-positive gay sexual networks.” Furthermore, when the ano-genital mucous membranes are abraded, weakened or otherwise damaged because of either of the following, HCV infection may also occur during sex:

  • STIs that cause inflammation or ulcers
  • prolonged use of oral erectile dysfunction drugs

This risk of HCV transmission is amplified, the researchers stated, in “a setting of fisting and sexually induced bleeding, particularly following ano-rectal surgery.” They also add: “If condoms are used but not changed for every new partner, [condoms might serve as a vehicle] for blood-borne viruses in a context of sex in a group, regardless of whether the insertive partner is infected with HCV. Similar cross-infection could be facilitated by sharing a glove during fisting or a rolled banknote used for [inhaling drugs].”

Research still needs to be done on the effect of ano-rectal surgery, damage to the mucous membranes and the “timing of restarting anal intercourse” after surgery, noted the scientists.

The German study provides an excellent foundation for developing educational efforts to minimize the spread of HCV among gay men.

                                                                                                            —Sean R. Hosein


  1. Adam BD, Husbands W, Murray J, et al. Silence, assent and HIV risk. Culture, Health & Sexuality. 2008 Nov;10(8):759-72.
  2. van de Laar T, Pybus O, Bruisten S, et al. Evidence of a large, international network of HCV transmission in HIV-positive men who have sex with men. Gastroenterology. 2009 May;136(5):1609-17.
  3. van der Helm JJ, Prins M, Del Amo J, et al. The hepatitis C epidemic among HIV-positive MSM: incidence estimates from 1990 to 2007. AIDS. 2011 May 15;25(8):1083-1091.
  4. Schmidt AJ, Rockstroh JK, Vogel M, et al. Trouble with bleeding: risk factors for acute hepatitis C among HIV-positive gay men from Germany—a case-control study. PLoS One. 2011 Mar 8;6(3):e17781.