Virus Hybridization Could Create Pandemic Bird Flu

According to a new study from the Proceedings of the National Academy of Sciences, genetic interactions between avian influenza (H5N1) and human seasonal influenza viruses have the potential to create hybrid strains combining the virulence of bird flu with the pandemic ability ofH1N1. The study showed that in laboratory experiments with mice, a single gene segment from a human seasonal flu virus, H3N2, was able to convert the avian H5N1 virus into a highly pathogenic form.

Based on reported statistics, once someone is infected, the H5N1 bird flu virus kills humans at a much higher rate than the H1N1 swine flu virus circulating amongst us in the current global pandemic. According to the World Health Organization (WHO), as of December 21, 2009, H5N1 had caused 447 confirmed human cases and 263 confirmed deaths. In addition, as of February 21, 2010, more than 213 countries worldwide had reported laboratory confirmed cases of pandemic influenza H1N1 2009, including at least 16,226 deaths.

When two different virus strains infect the same host, they often exchange genes in a process known as reassortment. Experts are concerned that as bird flu spreads more widely and infects more people, it will reach more individuals who are also carrying human seasonal flu viruses. This combination increases the likelihood of a new strain emerging that has the potential severity of the bird flu virus and the infection rate of the swine flu virus, leading to a new global pandemic with possible deadlier consequences than the one we experienced at the end of last year.

According to Dr. Kawaoka, senior author of the study, “With the new pandemic H1N1 virus, people sort of forgot about H5N1 avian influenza. But the reality is that H5N1 avian virus is still out there. H5N1 virus has never acquired the ability to transmit among humans, which is why we haven’t had a pandemic. The worry is that the pandemic H1N1 virus may provide that nature in the background of this highly pathogenic H5N1 virus.”

While vaccination offers the best protection against contracting H1N1, the CDC also recommendsother important preventive steps including:

  • Wash your hands often with soap and water. If soap and water are not available, use an alcohol-based hand rub.
  • Avoid touching your eyes, nose or mouth. Germs spread this way.
  • Disinfect to help destroy viruses and bacteria living on surfaces, especially frequently touched door knobs, hand rails, bathroom fixtures, kitchen counters and children’s toys. One tablespoon of household bleach in a quart of water makes a handy, inexpensive surface disinfectant. Wash surfaces first with soapy water and then apply bleach solution. Let air dry.
  • Try to avoid close contact with sick people.
  • If you are sick with flu-like illness, CDC recommends that you stay home for at least 24 hours after your fever is gone except to get medical care or for other necessities. (Your fever should be gone without the use of a fever-reducing medicine).

To read more about protecting yourself and your family against H1N1, visit for more information.

(Ralph Morris, M.D., M.P.H., is a preventive health and public health physician, and a member of the Water Quality & Health Council)