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Exploring what we thought we knew and what we think we know now about how hepatitis C is passed on.

In the 15 or so years after the discovery of hepatitis C virus (HCV), the evidence did not point to the virus being sexually transmissible. Thanks to mounting data over the last decade, researchers and clinicians now view the virus differently.

Here, Dr Chloe Orkin, Consultant and Honorary Reader in HIV Medicine at Barts Health NHS Trust, explains how the medical profession came to understand that HCV can be transmitted through sexual contact.

Hepatitis C was not originally believed to be sexually transmissible. Why did that belief change?

In monogamous heterosexual couples where one partner is HCV-positive and the other not, the transmission rates are very low. However, around 2004 a new ‘epidemic’ of hep C within the male gay community around the world occurred. Studies into sexual practices showed that one of the risk factors was ‘chem’ [drug-fuelled] sex.

So, we came to understand that it’s the type of sex that is key. The more robust the sex, the more likely that HCV is to be transmitted.

At what stage did the evidence emerge around sexual transmission?

This cluster of hepatitis C cases that occurred in mostly HIV-positive men who have sex with men was first reported in Europe. Then similar cases were reported in Australia and the United States, between 2004 and 2006. The co-associated factors were high-risk sex, ‘chem’ sex and STIs [sexually transmitted infections]. That cast a whole new light on how exactly it’s spread. 

Why might HCV be transmitted under these circumstances?

Transmission happens when you get tiny breaches of the skin, which can occur with anal sex whether you’re heterosexual or gay. It can also happen when you get tiny breaches in the nasal mucosa, that’s how it’s thought to be spread through the use of intra-nasal drugs. It can also be spread through intravenous drugs use. 

Is that why there is increasing discussion around contracting hepatitis C from rolled-up banknotes used for snorting cocaine?

Yes, and the straws used for snorting drugs. The fact is that as soon as there’s a tiny breach of the skin you can transmit hepatitis C. In cultures where public shaving happens, there might be transmissions when barbers use the same razors for different men. And also between infants when their heads are shaved before circumcision.

Is transmission possible via vaginal sex if there is a breach of the skin?

Yes, and if there is also an STI present it’s more likely to happen. It’s much less usual but it’s possible. 

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