Expert says H7N9 will not necessarily become transmissible among humans

Staff writer, with CNA

Wed, Apr 17, 2013 - Page 3

The H7N9 avian influenza virus will not necessarily become transmissible among humans, but it does have a mutated gene that makes such a possibility greater, an expert said yesterday.

The H7N9 virus, currently transmitted from poultry to humans, has spread widely in China, and health authorities in other countries are worried that the lethal bird flu strain could become transmissible among humans and pose a major challenge to epidemic controls.

Michael Lai (賴明詔), a research fellow at Academia Sinica specializing in corona-virus molecular biology, was reported as saying on Monday that the H7N9 virus is evolving and would mutate into a form allowing human-to-human transmission sooner or later.

However, Lai clarified yesterday that he did not say that the H7N9 virus would definitely become transmissible among humans, but that it has a mutated gene and may be more likely to cause a human pandemic in a short time if it infects more people.

Lai said he could not determine how the H7N9 virus would evolve, just as experts were unable to predict the pattern of the avian influenza A(H5N1).

Some said that the H5N1 virus would mutate and spread among humans, only to find that “many years have gone by and what everybody worried about has yet to happen,” Lai said.

The H7H9 virus does pose a bigger challenge than the H5N1, Lai said.

H5N1-infected fowl die easily from the virus, while H7N9-infected fowl live normally and show no symptoms, which is why the H7N9 is not easily detected and China is having a hard time finding its source, he said.

The H7N9 bird flu in China has spread to the north, seemingly following the route migratory birds take to their summer breeding grounds, Lai said, yet no migratory bird has died of the flu so far.

As a result, no conclusions can be drawn on whether migratory birds are H7N9 virus carriers, but if they are, Taiwan could become an H7N9-affected area when migratory birds begin flying south during the fall and winter, Lai said.

Taiwan has yet to get a close look at the H7N9 virus because it has yet to obtain samples of the flu strain, but Lai said that based on its gene sequence, the anti-flu medicine Tamiflu should be effective in combating it.