Italian researchers say they've determined, for the first time, a less-virulent strain of avian influenza virus might spread from poultry to humans.
Crossing the species barrier is an important step in the development of a flu virus with pandemic potential, the scientists noted. Previous studies have focused on the ability of highly pathogenic bird flu strains, such as H5N1 in Asia, spreading to humans.
The new study, however, shows less pathogenic strains are also capable of jumping to humans.
Isabella Donatelli of Istituto Superiore di Sanita in Rome and colleagues studied outbreaks in northern Italy occurring among poultry between 1999 and 2003.
The investigators said their work provides the first serologic evidence of transmission of low pathogenic strains of avian influenza virus to humans during an outbreak in domestic poultry.
The researchers emphasize their study probably underestimates the real infection rate because blood samples were considered positive only if they repeatedly produced unequivocal positive results using several different serologic techniques.
Details of the study appear in the Oct. 1 issue of The Journal of Infectious Diseases, now available online.
Copyright 2005 by United Press International
