Widespread use of the antiviral Tamiflu to fight pandemic avian flu in humans could actually lead to the development of what public health officials hope to avoid??drug-resistant strains of the virus in wild birds. British researchers at the Centre for Ecology and Hydrology in Oxford have released findings in the January 2007 issue of Environmental Health Perspectives (EHP) that demonstrate how Tamiflu?s persistence in wastewater and river water could affect the waterfowl that drink from those water sources.
Since the World Health Organization?s first warning of an avian flu pandemic two years ago, nations worldwide have been stockpiling Tamiflu for treatment and outbreak prevention. The drug, which minimizes flu symptoms and duration, inhibits the movement of the influenza virus from the cells it infects, and also helps uninfected people avoid contracting the flu. However, Tamiflu?s active agent, the metabolite oseltamivir carboxylate (OC) would be excreted into sewers for several weeks during a pandemic and is expected to withstand biodegradation. According to the researchers in the current study, once birds drink OC-laced water from catchments receiving treated wastewater, they could produce Tamiflu-resistant strains and pass them on to other birds who share the same waters.
The authors warn that, with the release of the uniquely structured, biochemically resistant OC antiviral into river water, “the range of OC concentrations predicted . . . will have uncharacterized ecotoxicological consequences.” They call for more detailed water contamination modeling, especially in high-risk areas of the world such as Southeast Asian countries, where there is more frequent human-to-waterfowl contact and where future use of Tamiflu would be significant. They also recommend development of methods to minimize the release of OC into wastewater systems, such as biological and chemical pretreatment in the toilet.