Monday, May 6, 2013

The New Asian Bird Flu

     I thought I would share some facts with you about the new strain of influenza A H7N9, that has arisen in China and probably comes from birds, although we are not 100% certain of that. There has, as yet, been no evidence of people-to-people transmission (unlike SARS which infected health care workers). Furthermore, although this flu strain is resistant to amantadine, it is susceptible to oral oseltamovir  (Tamiflu).

     As of the end of April, there have been 126 confirmed cases in China, and 24 or 19% died. Older people are more susceptible to both catching the flu and succumbing to it, especially if they have a chronic health problem. Cases have been found in eight contiguous provinces in eastern China as well as in Beijing, Shanghai and Taiwan. China is making prodigious efforts to learn all it can about the flu and the birds' contribution to it. The flu has been found in some chickens and ducks, but the flu virus is harmless to poultry, and birds  who are infected with the virus show no signs of being ill.

     Thankfully, in the over 1500 close contacts of sick patients there has been no evidence of the flu, so unless it mutates there is no risk of an epidemic or pandemic. Except for one pigeon, the virus has only been found in chickens and ducks for sale in marketplaces; farms seem to be exempt. Relatively few poultry are carrying the virus, and 20% of the people with the virus report no exposure to birds. Chinese physicians and technicians are making herculean efforts to track and to find the virus, as well as sequencing its genome, and are examining pigs as well as poultry.

     China has invited members from the World Health Organization as well as from our own Center for Disease Control to come and assist in their work. In addition, the CDC is monitoring patients here in the US for cases of Influenza A/H7N9, but so far have found no cases. There is not even the suggestion of facts or cases being hidden by China, so whatever you read should be accepted.

     In summary, the virus is mild and relatively rare in poultry,  but has a case fatality rate of 20% in humans, and while we think that poultry is the reservoir, we are not yet sure.



  1. The New England journal of Medicine edition published on May 16, 2013 (vol.368) has two important articles. There is an editorial discussing the flu on pp 1862-1864 by T. Uyeki et. al. There is a report of the first three Chinese patients who developed the flu and who died from ARDS and multi-organ failure on pp 1888-1897 by R. Gao

  2. The Center for Disease Control now recommends immediate treatment with ostelamivir as soon as infection with H7N9 flu is suspected.

  3. However, the first cases of resistance to ostelamivir has been reported in two patients.