Doctor, what can you tell me about the bird flu?
In the past two years, there has been tremendous interest in the bird flu (or avian influenza) illness. There is definitely a big uproar in the media. I will explain some of the facts and concerns regarding the bird flu hype.
The current uprising in cases of avian influenza in Asia is not the first epidemic in its existence. In fact, there were two other pandemics of bird flu. One occurred in 1957 and the other took place in 1968. The latest avian influenza is a sub-type of the influenza virus, namely H5N1. Its unique genetic makeup and transmission mechanisms are very similar to the common flu (influenza A and B) virus that we encounter every winter.
Avian influenza infects mainly birds and fowls. Influenza A and B infects humans readily. The transmission of avian influenza from animals to humans occurs very rarely. At the time of this writing, there were close to 200 human cases reported worldwide so far.
The pathogenic avian flu has caused outbreaks across Asia, including Cambodia, China, Kazakhstan, Indonesian, Malaysia, Mongolia, Thailand, Vietnam and Russia. However, because of natural bird migration patterns, there is growing concern that the avian flu virus might be spreading to Romania, Greece, Croatia and Turkey. In fact, there have been cases reported in Africa and France already.
Transmission of these types of virus is usually by inhalation of infectious droplets, by direct contact, and by indirect (object) contact. Bird-to-bird transmission is very common. However, bird-to-human transmission is possible but not as prevalent. In Hong Kong, a study showed about 3 percent of government workers and 10 percent of poultry workers had the avian flu viral antibody in the blood but these workers were not clinically sick with the disease. The study concluded that bird-to-human transmission of avian influenza is possible, especially in a human who has more direct and close contact with the sick birds. However, the actual manifestation of the disease is unknown. Human-to-human transmission is even more uncommon, although a handful of family cases has been reported worldwide.
Presenting symptoms are very similar to those of the common flu virus. Features include fever, upper respiratory tract symptoms and dysentery symptoms. In contrast to the common flu, gastrointestinal symptoms appear to be more frequent with the avian flu. Unfortunately, pneumonia occurs in half of the cases. Diagnosis can be made by viral culture, RNA study or antibody level, if the clinical suspicion is high. High-risk patients who have a history of travel within 10 days of symptom onset to a country with documented H5N1 avian influenza should be tested.
There are two classes of anti-viral agents that are effective against avian influenza. However, there are no outcome trials that have been performed on humans. Presently, there is no licensed vaccine against avian influenza.
Because migratory bird patterns travel from Northern Europe to Canada and then from Canada to the United States, it has caused a major concern for U.S. farmers and politicians. How are we going to prevent such an outbreak such as the one in Asia?
Nobody really has a solid solution to this issue. Some believe that the avian flu will occur in America within the next six months. Some believe that even if the virus migrates to our continent, an epidemic wouldn’t occur since almost all of our commercial chicken ranges are located indoors and contact with migratory birds would be rare.
Yet, only the testament of time will determine our fate.