Avian Influenza

Avian influenza is also called "bird flu" and is a virus that has the potential to affect birds as well as humans. Wild birds get this flu quite often and this gets spread to tame birds. If a person is in close contact with sick bird, he or she can get an avian flu infection. It has been known to infect, ducks, chickens, and turkeys and is often deadly in these species. Infected birds shed the influenza virus in their nasal secretions, feces and saliva. The transmission of avian flu among birds can come from any of these routes of infection. Tame birds can get two types of infection: a low pathogenic form, which does not kill the birds and a high pathogenic form that can kill the birds at a rate of 90 to 100 percent within forty eight hours.

Avian flu is a type A influenza virus which fortunately has treatment available to it. There are about nine known neuraminidase influenza A viruses, of which bird flu is one of them. Birds can get the other known subtypes of avian flu as well.

Avian flu can infect humans as well. The risk is currently low to people and is confined to those with direct contact with sick birds. There have been confirmed cases of avian flu since 1997 but the rate is currently increasing. There has been rare transmission of the avian flu virus from human to humans but it is expected that transfer from coughing or sneezing between humans can happen with a simple change in the DNA of the virus particle. So far there has been no sustained outbreak of the disease.

The subtypes of human influenza A in humans include H2N2, H1N1 and H2N2. The H1N1 virus has been the one related to avian flu. Some aspects of all type A flu viruses have had their origin as bird flues so there is every reason to expect that H1N1 will mutate and form a transmissible disease among humans.

The symptoms of avian flu in humans have been typical influenza like symptoms, including cough, fever, sore throat, GI symptoms and muscle aches. The secondary affects have included eye infections, pneumonia and respiratory distress.

The highly contagious form and highly pathogenic form of the avian flu is most commonly seen in birds; however, some people have died from the avian flu. It is the H1N1 strain of the virus that is so deadly. Milder cases might have existed but weren't reported due to their mild symptoms. The most severe cases, including human to human pathogenic spread, have been seen in Asia and Africa. It results in death in nearly 60 percent of all known cases.

There was a case in Thailand in which there was a family that suffered from person to person spread. Eight people were infected after a mother and child got the disease. It is not known exactly how the disease spread to other family members but raised the question of human to human spread being a possibility in other parts of the world in the near future. A catastrophic pandemic could occur because people have little or no immunity against H1N1 virus particles.

The treatment of H1N1 virus infection in humans includes the drugs called amantadine (Symmetrel) and rimantadine. These are specific antiviral agents against influenza type A. These agents must be given as soon as the symptoms develop for the best effectiveness-at least within forty eight hours after the symptoms begin to occur. Resistances to the H1N1 virus are also possible so vaccines are in the works so that the person can develop the immunity to the virus before the pandemic outbreak occurs. Two other antiviral agents are being studied for the disease.