Cornell researchers find waste treatment kills deadly avian flu
Studies on a similar but less-virulent strain show that UV, chlorine, and digesters are almost equally effective in killing it; avian flu already known to do poorly outside of host; study should lift the hopes of municipal water suppliers
We typically drink coffee where others enjoy water, but nevertheless we are pleased to hear from Cornell University scientists that the avian flu virus, known to the scientific-minded as H5N1, is extremely suspectible to waste water treatments. Public health officials have long been worried that the virus might leech into the water supply (although it is already known to do poorly outside a host) and so the recently released study, which found that chlorination, ultraviolet, and bacterial digesters were succesful in killing it, is a relief on that front. “You have some 50,000 treatment plants in the U.S., and all these operators that run the plants were concerned that if there were an influenza outbreak and everyone were sick, is it going to come into the plant and infect them and others,” said professor of parasitology Dwight Bowman.
An important caveat: Because H5N1 is so virulent, researchers employed a related but low-pathogenic influenza virus known as H5N2. In order to test the effectiveness of UV radiation treatment, researchers exposed the virus in drinking water as well as in wastewater effluents to UV light at varying levels. The treatment was very effective in killing H5N2 at levels well within industry standards (and at lower levels than are used for killing Cryptosporidium and Giardia in water). Likewise, bacterial digesters also reduced H5N2 to undetectable levels after seventy-two hours, well within industry standards. (Higher digester temperatures inactivated the virus more quickly.)
The results for chlorine were less defintive but still promising. Researchers found that inactivation of H5N2 depends on both chlorine concentrations and time of exposure. On average, experts say, U.S. treatment plants treat drinking water with chlorine concentrations of 1 milligram per liter for 237 minutes. Under these conditions, the researchers found that H5N2 (and probably H5N1) would be mostly inactivated, but further studies are needed to see if the viruses stay active when they come out of feces or are at different pH and salinity levels.
Researchers at Cornell and at West Point collaborated on the study, which was recently published in the journal Environmental Engineering Science.
-read more in this university news release
