Avian Influenza (H5N1) By Mark B. Levin, M.D. The Pediatric Group, P.A., Princeton

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The media and political hype sometimes relegate science to the recesses of our minds. With a clear understanding of the facts, however, we can make rational judgments about life's challenges and reduce worry.

The virus that causes avian, or bird, flu is categorized by its antigens as H5N1. This virus differs markedly from the annual occurrence of types A and B influenza virus that infect humans. Avian flu rarely infects humans, and then only via frequent contact with feces, blood or saliva from infected birds (usually fowl). Although rare, human infections from avian flu are more severe than influenza A or B.

The fear of avian flu stems from the historic 1918 influenza epidemic that killed millions and was caused by a virus similar to the H5N1 virus. The infamous lethality of the 1918 virus, however, might not be applicable to current conditions. Many of those who died in 1918 succumbed to secondary bacterial infections, such as pneumonia and bacteremia. Different from the situation in 1918, today we have antibiotics (penicillin, the first antibiotic discovered was not stumbled upon until the late 1920s).

We can certainly understand fear of an illness that claimed so many lives. When the media talks about the more than 60 people dead from the current strain of avian influenza, they omit two vital pieces of information. First, that number has accumulated over the last few years, not over the last few days or months. Second, nearly all the deaths have been associated with having tended flocks of birds. In the far East, people who raise birds for a living actually have the birds in their yards and in their living quarters. The ground and outdoor furniture may be covered with bird feces. When slaughtering birds for market, far eastern poultry farmers seldom practice sanitary conditions like those maintained in commercial slaughterhouses in the U.S. Consequently, these bird farmers are often splattered with infectious bird body fluids.

Although we here do not handle live infected birds as is done in the far East, eating undercooked infected birds can result in mammalian infection with H5N1. In early 2005, nine tigers reportedly died from being fed raw infected chicken. Cooked chicken is not infectious. No human cases of this sort have yet been reported. The cause of the few suspected cases of human-to-human transmission is uncertain. Victims were near, but not handling, infected bird body fluids. One woman, who was suspected as having gotten the infection from her husband, habitually sat on a bird-feces-covered bench outdoors while her husband worked. A teenage boy, who was suspected of getting avian influenza from his father, was standing next to his father while the father was slaughtering chickens for market. The stories were collected retrospectively by interviewers. As talented as these interviewers are, there is abundant data to suggest that data obtained by this technique may be unreliable.

In order for avian influenza to become regularly infectious to humans and to be transmissible from human to human, it must mutate by either of two possible mechanisms. The more likely mechanism involves simultaneous co-infection of mammalian cells with either influenza A or B and H5N1 virus. If a pig, for example, became infected with both viruses, the viruses would have the opportunity to exchange large amounts of genetic material and produce a bird influenza virus capable of easily infecting mammals. The less likely mechanism would entail the avian influenza virus developing multiple mutations rendering it capable of infecting human cells. In either case, the likely unfortunate subjects of this viral invasion would be those living in the far East sharing real estate with birds infected with the avian influenza virus and pigs. Even in an age of air travel, any epidemic would likely begin there, giving the rest of the world some time to institute protective measures, such as quarantine, preventative medication or immunization.

Public health and Infectious Disease experts are tirelessly exploring preventative and therapeutic options. While there is some controversy regarding the possible effectiveness of currently available anti-influenza medications, there is optimism regarding a vaccine developed in China. That vaccine is currently undergoing clinical trials to determine safety and effectiveness. Certainly, the situation requires that the infectious disease experts around the world remain vigilant and diligent. The general public need not be building bunkers, stocking up on medications (which may even be useless in a bird flu pandemic) or hibernating in South America for this winter.

Dr. Mark B. Levin

Dr. Levin has been a member of the staff at The Pediatric Group since 1977. Currently an attending Pediatrician at the Medical Center at Princeton, he has been Chairman, Department of Pediatrics, Medical Center at Princeton, 1984 to 1986, 1989 to 1992, and past President, Medical and Dental Staff, Medical Center at Princeton, 1987 to 1988. Dr. Levin has served on numerous Departmental and hospital committees. He has published original articles both while at Upstate Medical Center in Syracuse and at The Pediatric Group. He has a wife and three children. Dr. Levin enjoys alpine skiing, jogging, hiking and camping, travel, computers and racquetball.

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