H7N9 Avian Virus Easily Transmissible in Animals: Study

Scientists from China and the U.S. conducted a study to determine whether the H7N9 avian influenza virus could infect and be transmitted between ferrets and to check this they collected the virus from a person who had died from H7N9.

Ferrets are often used as mammalian models in several influenza researches. The study of the transmission of H7N9 virus between ferrets can offer strong hints as to how the same process might take place in humans.

The researchers dropped the H7N9 virus strain into the noses of six ferrets. A day later, the researchers placed three uninfected ferrets alongside the infected ones in a cage and three uninfected ferrets were kept in cages nearby.

The researchers noticed that all the uninfected ferrets that were placed within the cage became infected while only one of the three uninfected ferrets placed near the cage caught the virus. From this the researchers conclude that the ferrets are susceptible to the virus and the same can be transmitted between ferrets by both direct contact and less efficiently by air.

One day before the clinical signs of the virus became evident; the scientists had detected the viral material in the nasal secretion of the ferrets.

The suggestion offered by this observation is that those infected with the H7N9 avian influenza virus might not display any symptoms but could however spread the virus to others.

Apart from ferrets, the researchers also infected pigs with the same H7N9 virus that was derived from human. In a natural setting, pigs can combine both avian and mammalian influenza strains thereby permitting the avian strains to adapt well to humans. The strains arising from this combination have the potential to infect humans and cause a pandemic.

Unlike the ferrets, the pigs in this study displayed a mild sign of illness consisting of nasal discharge, sneezing and lethargy. But none of the infected animal became seriously ill.

This study was supported in part by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.