Evidence to support belief in transmission of hepatitis C by sharing drug sniffing equipment

Hepatitis C can be detected in the nasal passage, and in straws which are inserted in the nose, report researchers in the October 1^st edition of Clinical Infectious Diseases. Their findings support the hypothesis that hepatitis C can be transmitted by sharing straws or banknotes which are used to snort drugs.

The theory of hepatitis C transmission through this route is that frequent or long-term sniffing or snorting of drugs such as cocaine can cause damage and bleeding in the nasal passage. Straws or banknotes that are inserted in the nose could come into contact with hepatitis C infected blood or mucus, which may then be transmitted to someone else sharing the same straw.

In recent years there have been numerous outbreaks of hepatitis C among HIV-positive gay men in Europe. Whilst there is a growing body of evidence that infection is associated with sexual practices including fisting, use of sex toys and group sex, some studies have also suggested that sniffing drugs may contribute to transmission.

At the same time, in many countries up to a quarter of hepatitis C infections remain unexplained, with individuals reporting no risky practices such as use of shared drug injection equipment.

And a number of epidemiological studies in largely HIV-negative populations (typically, blood donors or street drug users who do not inject) have found an association between snorting drugs and hepatitis C infection. Nonetheless not all studies have reported this finding, and there have been some criticisms of the methodological quality of these studies.

However, until now no study has examined the virological plausibility of the belief that sharing equipment to sniff drugs may contribute to hepatitis transmission. Investigators in New York therefore recruited 38 adults who snort drugs and have hepatitis C at a neighbourhood health clinic.

Tests conducted included:

• Nasal swabs to test for the presence of hepatitis C and blood in the nasal passage
• Each subject was asked to inhale air through plastic straws, which were then tested for hepatitis C and blood
• An examination of the nasal cavity to check for disease.

In these tests, hepatitis C RNA was detected using the same sort of technology as a viral load test.

A third of the sample was coinfected with HIV, and 45% with hepatitis B. Hepatitis C viral load varied widely in the sample, with a mean of 5000 copies/ml. Liver function tests for ALT (alanine aminotransferase) indicated some damage, with a mean of 47 u/l.

The researchers were able to detect hepatitis C on 13% of the nasal swabs, and on 5% of the sniffing straws.

Blood was detected in the samples more frequently than hepatitis C. However whether blood was present or not did not predict whether hepatitis could be found. For example, of the five nasal swabs that were positive for hepatitis, there were no traces of blood on two of them.

Pathologies and damage to the nasal passage could increase the risk of hepatitis transmission. Among other problems, more than four out of ten subjects reported having a runny or stuffy nose at least once a week. Rates of inflammation of the nasal membrane were high at 71%, while rates of inflammation of the sinuses were normal.

It is known that hepatitis C can remain infectious outside the body for up to 16 hours. However the authors acknowledge that little is known about the quantity of virus needed for transmission. They suggest that when drugs are being snorted, there is greater discharge of nasal fluids and blood, and the quantity of virus is likely to be larger.

The authors believe that their most significant finding is that hepatitis C can be transferred onto sniffing implements. Nonetheless they recommend further studies to confirm this mode of transmission and its contribution to the spread of hepatitis C.