(NaturalNews) Even as governments and health experts around the world have been focusing on the threat of a pandemic of the H5N1 strain of avian flu, another dangerous strain known as H9N2 has gone mostly ignored, according to a study published in the journal
PLos ONE.
"Our results suggest that the establishment and prevalence of H9N2 viruses in poultry pose a significant threat for humans," the researchers wrote.
Of three known species of influenza virus, two of them regularly infect humans. The third species,
influenza A virus, primarily affects
birds and is also known as
bird flu. Among hundreds of strains of influenza A, the World Health Organization says that only four have ever been known to infect humans:
H5N1, H7N3, H7N7 and H9N2.
H5N1 has attracted the most attention due to its extreme virulence and high death rate - of 385 humans known to have been infected with the
virus since 2003, 243 have died. The virus is widespread in both domestic and wild bird populations, giving rise to fears that it could mutate into a form more easily transmissible to and between humans.
But H9N2 can also cross from birds to pigs, humans and other animals, and has infected at least four Hong Kong children to date. In its current form, the virus causes only mild symptoms. In the current study, however, researchers found that a single mutation was enough to make H9N2 more infectious and virulent, but also to enable it to cross directly between infected ferrets.
Ferrets react to influenza similarly humans, and are often used as an animal model for the disease.
Hybridization of the H9N2 and H3N2 strains also resulted in a more pathogenic and easily transmitted
flu. Researchers believe this could occur if a single organism is infected with both strain simultaneously
Neither of the laboratory-produced strains was able to spread through the air and could only spread by touch, similar to colds.
Sources for this story include:
www.reuters.com.
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