Sharing drug preparation equipment a potential source of hepatitis C transmission

Drug users who share injecting equipment such as water, filters and water containers are potentially putting themselves at risk of infection with hepatitis C virus (HCV), according to German research published in the online edition of the Journal of Infectious Diseases.

“We demonstrate that HCV can be directly associated with drug preparation equipment like water, filters and water containers,” write the authors. “These findings add strong evidence to the high transmission rate of HCV when sharing these drug preparation materials and should help in the design of prevention strategies aimed at reducing HCV transmission.”

Hepatitis C is a blood-borne virus and injecting drug use is a major mode of transmission. It is estimated that 60% of newly acquired hepatitis C infections involve individuals who inject drugs.

The virus can contaminate injecting equipment at all stages of the injecting process, which involves several steps and a number of different pieces of equipment.

Transmission of the virus between injecting drug users has mainly been associated with the sharing of syringes. The implementation of prevention campaigns targeting the sharing of syringes has been associated with a reduction of hepatitis C incidence among injecting drug users.

However, the sharing of other equipment used during the injecting process persists, and this may explain the continuing high rates of hepatitis C transmission involving people who inject drugs.

Therefore investigators in Germany designed a laboratory study looking at the persistence of hepatitis C virus in water, filters and water containers.

100ml of drinking water in plastic bottles was contaminated with hepatitis C and incubated for several days at room temperature. Contaminating doses of hepatitis C ranged between 500µl and 1.5µl.

At the highest dose of 500µl, infectivity was reduced tenfold after ten days. However, it could still be measured at infectious quantities after 21 days “demonstrating a stability of infectious HCV for more than 3 weeks in water under these experimental conditions.”

A dose of 200µl showed a similar rate of decay, but was undetectable after three weeks. The 100µl dose was no longer infectious after four days, and the 1.5µl dose was not infectious at any time point.

Water contaminated with infectious quantities of hepatitis C was placed into plastic, aluminium and glass containers. The water was then discarded and the containers refilled. However, even after refilling, the investigators found HCV-contaminated fluid in both the plastic and aluminum containers.

“We propose that infectious HCV particle association with water container material is directly connected to the fact that residual contaminated water associated differently with the container depending on type and material,” comment the investigators. “For plastic, it is a general phenomenon that small drops are associated to the bottle neck which is observed to a much lesser extent with glass material.”

The authors also contaminated filters with hepatitis C, which were then wrapped in foil, a common practice among drug users. Infectious quantities of the virus were still detectable in the filters 24 and 48 hours after initial contamination “demonstrating prolonged stability of HCV in foil protected filters.”

“The findings described here should help to raise awareness and emphasize the risk of sharing drug preparation materials,” conclude the investigators. “Prevention messages and campaigns should be revised to notify people who inject drugs to the importance of eliminating all equipment-sharing practices and supply of sterile equipment is recommended.”

Doerrbecker J et al. Transmission of hepatitis C virus among people who inject drugs: viral stability and association with drug preparation equipment. J Infect Dis, online edition, 2012.