Hepatitis C Virus Can Live on Surfaces for Up to 6 Weeks

Hepatitis C virus (HCV) in dried droplets of blood or plasma can remain infectious on uncovered surfaces at temperatures of 4° or 22° C (39° or 72° F) for up to 6 weeks, resulting in potential for transmission in healthcare settings or during injection drug preparation, researchers reported in the November 23, 2013, advance edition of the Journal of Infectious Diseases.

HCV is readily transmitted through direct contact with blood, for example due to an accidental needle-stick or sharing syringes for injecting drugs. Less is known about how long the virus can remain viable and infectious on surfaces that have come into contact with blood or other body fluids containing HCV.

Elijah Paintil from Yale School of Medicine and colleagues conducted a study to determine the duration of HCV infectivity on "fomites," or inanimate surfaces that can serve as a route for transmission of pathogens.

To simulate a real-life situation, the researchers first determined the volume of misplaced drops during transfer of serum or plasma, as may occur during healthcare procedures such as placing venous lines.

They then added a genetically engineered genotype 2a HCV "reporter virus" to samples of the same volume, placed them on 24 plates, and allowed them to dry out uncovered at temperatures of 4° C (refrigerator temperature), 22° C (room temperature), and 37° C (body temperature) for up to 6 weeks.

Results

• The mean volume of an accidental drop was 29 mcl (range 20-33 mcl).
• At storage temperatures of 4° and 22° C, viable HCV was recovered from low titer spots after up to 6 weeks.
• At 37° C, infectious HCV was recovered only up to 7 days.
• HCV infectivity declined rapidly during the first 2 weeks of storage, followed by a slower decline.
• Bleach (1:10 dilution) was the most effective antiseptic tested, with 1 minute of exposure eliminating infectious HCV in 100% of spots, followed by the commercial medical disinfectant CaviCide (1:10 dilution; 94% of spots) and 70% ethanol (87% of spots).

"The hypothesis of potential transmission from fomites was supported by the experimental results," the study authors concluded. "The anti-HCV activity of commercial antiseptics varied."

"This finding supports our hypothesis that the increasing incidence of nosocomial [acquired in healthcare settings] HCV infections may be due to accidental contact with HCV-contaminated fomites and other hospital equipment even after prolonged periods following their deposition," they elaborated in their discussion. "Furthermore, the commercially available antiseptics reduced the infectivity of [HCV reporter virus] on surfaces only when used at the recommended concentrations, but not when further diluted."

"Of infection control relevance is the fact that all the [HCV reporter virus]-contaminated spots dried at room air within 4 hours, becoming inconspicuous and therefore more likely to cause accidently exposures to HCV," they added. "The prolonged infectivity of these viruses [HCV and HIV] has been attributed, in part, to their lipid envelope, which resists drying and protects the viral capsid from the deleterious effects of dehydration."

Paintsil's group previously reported that HCV can survive in syringes for up to 2 months under certain conditions. The present findings may help explain how other injection equipment that comes into contact with blood can also transmit infection. While the researchers do not discuss other modes of transmission, exposure to dried virus on surfaces may also contribute to HCV sexual transmission.

12/12/13

Reference

E Paintsil, M Binka, A Patel, et al. Hepatitis C Virus Maintains Infectivity for Weeks after Drying on Inanimate Surfaces at Room Temperature: Implications for Risks of Transmission. Journal of Infectious Diseases. November 23, 2013 (Epub ahead of print).