Growing concerns over H7N9

The novel avian influenza A(H7N9) virus has infected more than 100 people, killed more than 30 and concern is growing on whether it will develop to transmit from human to human, according to experts who spoke at the 2013 General Meeting of the American Society for Microbiology in Denver.

“If that particular virus were able to spread between humans we could end up with an enormous outbreak,” said Albert Osterhaus, PhD, head of the department of viroscience, Erasmus MC University Medical Center in Rotterdam, the Netherlands, “We have to invest in pandemic preparedness.”

Robert Webster

Robert Webster, PhD, of St. Jude Research Children’s Hospital in Memphis, Tenn., said the two avian influenza viruses to be most concerned about are H7 and H5. H5 appeared in Hong Kong and was nonpathogenic, and when poultry markets were closed the strain disappeared and has not been seen again. On April 6 in Shanghai, poultry markets were closed and no more cases have occurred in that area; however, markets have started to reopen.

“The problem with H7 is that it is nonpathogenic,” Webster said. “We know the source of H5 is the aquatic duck. What is the source of H7? We don’t know. … That is the concern at the moment.”

According to Carole Heilman, PhD, of the NIH and the National Institute of Allergy and Infectious Diseases, the US Department of Agriculture also is concerned with introducing the H7N9 strain to poultry in the United States.

Another concern presented at the session is that avian influenza tends to be seasonal.

“We’re going into the summer period, so by definition there will be a decline,” Osterhaus said. “We need to stay on our toes so that when this virus pops up again we are still aware that it is a serious thing.”

If H7N9 were to become a pandemic, Heilman said the US Department of Health and Human Services has a task force to determine whether there is enough potential of the virus becoming a serious problem.

“At this time, we are screening potential antivirals that have potential,” she said, adding that HHS is taking opportunities to look at other prevention strategies.

There has been an animal model developed for a potential vaccine against the virus, according to Osterhaus.

“There is a problem with human vaccines, if there is a pandemic, it goes worldwide,” he said. “The last pandemic … that was the first where we had vaccines. If you look at the Southern Hemisphere when the vaccine arrived, it was after the pandemic. We have to be careful. What we need to do today is look for possibilities of distribution of these vaccines worldwide.”

Heilman said there are some strains of influenza that have the potential to develop vaccines against.

“The H7N9 alerts us to what nature can do,” Webster said. “Nature is the ultimate bioterrorist. We have to go ahead and make vaccines, make antivirals because we know sooner or later [a pandemic] will happen.”

For more information:

Pandemic threats from emerging avian influenza viruses (H7N9 and H5N1): Challenges for public health, research, surveillance and countermeasures. Presented at: 2013 General Meeting of the American Society for Microbiology; May 18-21, 2013; Denver.

Disclosure: The researchers report no relevant financial disclosures.