Recently you may have seen or heard reports of out breaks of “bird flu.” In Minnesota there have been over five million domestic turkeys and chickens that have died as a result of the outbreak. Many of the birds have been destroyed due to exposure to the virus. There have not been any known human cases though the bird flu can have some implications for humans.
“Bird flu” (or avian flu) refers to infections in birds caused by influenza A viruses. Influenza A viruses are identified by chemical markers and are labeled with an H and N. For example the H1N1 flu virus refers to a specific combination of H and N chemicals that have caused outbreaks of illness in people. The H5N1 type has been causing illness in birds. These viruses are known to infect wild birds world-wide. Some strains of the virus can cause only minor illness while other strains can be deadly. The virus is contagious and is transmitted through contact with bird secretions or droppings. Domesticated birds like turkeys, chickens, and ducks being raised in farms tend to live in close quarters and are highly susceptible to infections. Once the virus is identified in a flock, the entire flock has to be killed to keep the infection from spreading.
There have been some human infections from other strains of the bird flu yet those were rare. The current strain of influenza A causing the outbreak in birds has not been associated with documented human infections. However, precautions are being taken by humans who are handling the infected birds.
Influenza A viruses have the potential to change. Influenza may change as it infects animals like birds and pigs (swine) that can transform into strains of flu that could cause human epidemics. That is why experts monitor the animal infections across the world. People develop immunity to certain H and N strains to protect themselves from infection. The vaccines are designed to provide protection against specific strains of the virus. But if the H and N combinations change, there may not be immunity to that new strain. That is why the flu vaccine changes and is recommended every year.
The recent outbreaks have been important because of the loss of domestic animals and the financial losses to the farmers and meat processors. That is why it has been in the news. Humans should take precautions to prevent infection. These include avoiding handling of dead or diseased birds and careful hand washing and hygiene when handling domestic poultry. There is no danger of contracting disease from ingesting poultry. So there is no need to avoid eating properly cooked and processed poultry.
The flu vaccine for humans is given in the fall and is directed toward the flu viruses that are predicted to infect humans. This vaccine does not include the strains that cause bird flu.
Hopefully, the current outbreaks of bird flu will come under control through the efforts of the farmers and veterinarians. But, outbreaks are likely due to the mobility of birds and their ability to transmit the virus. There is currently no imminent danger to humans. Stay healthy my friends.
By: P. Michael Shattuck, M.D. – Community Health Network Family Physician
