December 20, 2013 |
Yale researchers from the schools of public health and medicine have proven that an accidental drop of the hepatitis C virus (HCV) can remain infectious on surfaces for up to six weeks at room temperature.
The finding provides biological support for epidemiological data that hospital-acquired HCV infections may be due to contact with objects or substances capable of carrying an infectious organism such as HCV and that unhygienic surfaces may contribute to the rapid spread of HCV among people who inject drugs.
Professor Robert Heimer and Yale School of Public Health researchers Mawuena Binka and Amisha Patel collaborated with colleagues at the Yale School of Medicine led by Elijah Paintsil, assistant professor of pediatrics and pharmacology, on the laboratory experiment that was designed to simulate a real-life scenario. Coauthor Brett D. Lindenbach, associate professor of microbial pathogenesis, created a genetically engineered strain of the virus that was key to undertaking the experiments.
The scientists prepared tiny amounts of the virus in human plasma and measured its longevity at different temperature settings. They found that HCV remained infectious for up to six weeks between 4 degrees and 22 degrees Celsius. Infectivity was further influenced by the concentration of the virus and the humidity of the storage environment. Commercially available antiseptics, meanwhile, were found to be effective disinfectants if used at the recommended concentrations but not when diluted. The study was published recently in the Journal of Infectious Diseases.
“Our findings clearly demonstrate that strict infection control practices and universal precautions are needed in the clinical setting to avoid contact with infectious agents such as HCV that can survive on surfaces,” said Heimer. “The implications go beyond the clinic to the risk environment of people who use syringes outside of medical care settings. Unsafe practices, such as sharing of syringes by people who inject drugs or careless handling of human blood during home delivery of intravenous medications, can lead to HCV transmission.”
While there have been previous studies on HCV infectivity and stability on surfaces, the Yale research is believed to be the first that closely simulates the natural events likely to result in transmission.
HCV continues to exact a heavy public health toll around the world. It affects the liver and in up to 80 percent of infections, which leads to scarring of the liver and often to cirrhosis or liver cancer. There are more than 170 million people infected with the virus and no vaccine is available. Treatment options are limited by efficacy, cost and side effects.
The disease is primarily transmitted through parenteral exposure to blood or bodily fluids contaminated with HCV. Injection drug use, mother-to-child transmission, multiple heterosexual partners especially in the context of HIV-coinfection, accidental needle injuries and transfusions of blood or blood products are among the risk factors.
Hospital-based transmission of HCV accounts for an increasingly large proportion of new infections, especially in developed countries. By some estimates, this mode of transmission accounts for 20 percent to 50 percent of new infections. Much of the remainder comes from unsafe injection of drugs.