July 16, 2007

Higher temperatures and salinity affect bird flu virus persistence in water

Higher temperatures and more salty water can reduce the persistence of the H5 and H7 viruses in wild bird populations, according to J.D. Brown and colleagues, University of Georgia, Department of Population Health at the University of Georgia.

Brown and colleagues said bird flu viruses were spread when their feces landed in water, thus causing contamination among wild water fowl. Their study aimed to find out the persistence of the virus in these waters. The study was published in Avian Diseases. 

The study aimed to provide initial data on persistence of H5 and H7 viruses in water, by evaluating eight wild-type low-pathogenicity H5 and H7 viruses.

The persistence of two highly pathogenic avian influenza (HPAI) H5N1 viruses from Asia was also examined.

Viruses were tested at two temperatures (17 deg C and 28 deg C) and three salinity levels (0, 15, and 30 parts per thousand sea salt).

The wild-type H5 and H7 AIV persistence data indicate that both can persist for extended periods of time in water, with its persistence inversely proportional to temperature and salinity of water. That means hotter and more salty water wears down its persistence more.

The effect of salinity is more prominent at lower temperatures, the researchers noted.

Results from the two HPAI H5N1 viruses from Asia indicate that these viruses did not persist as long as the wild-type viruses.