Rowan?s Joanne Scott Looks at Avian FluNovember 21, 2005
As avian (bird) flu continues to surface in news stories, Dr. Joanne Scott, a biological sciences professor at Rowan University, is only half kidding when she says if birds eliminate on her car she?ll get it washed in a drive-through facility rather than do it herself.
Scott, who earned a Ph.D. in human genetics from University of Texas Medical Branch at Galveston, M.A. in education from Lehigh University and M.S and B.S. in biology from Bucknell University, has researched immunology, among other fields, and teaches virology.
If avian flu hits this country, she suggests the following:
-- Avoid poultry farms.
-- Wash hands, countertops and cutting boards thoroughly after handling poultry in the kitchen.
-- Avoid open-air markets that might have live poultry
Still, she says, there are no known birds in the U.S. that have the disease, also known as H5N1 flu. And whether avian flu will hit the United States bird population is unpredictable. If it does, the country could face problems that range from mild to catastrophic. Wild birds, Scott says, are the natural host for all subtypes of influenza A virus, and the viruses are very contagious among birds. Most of the time, when wild birds are infected with a flu virus, they don?t get sick. When wild birds pass the viruses to domestic poultry, such as chickens and turkeys, however, the domesticated birds often die.
The greater problem for humans would come if the disease crossed species, a rare happening.
Occasionally a virus will mutate, however, and it can infect people as well as its natural animal host. When a virus mutates and ?jumps? to another host, the results are unpredictable. Sometimes, the mutated virus causes only a mild illness, but other times it can make the new host extremely sick, even if the original virus didn?t make the natural animal host very sick.
About one-half of all types of viruses, including flu viruses, have genes made of RNA instead of DNA. Viruses with RNA genes tend to mutate more often than viruses with DNA genes. This results in many different strains of flu viruses, and these strains continue to mutate every year. When a virus mutates, the types of proteins on the surface of the virus change. Human immune systems normally can recognize the ?foreign? proteins on the surface of the virus, and white blood cells attack and destroy the cells in humans that get infected, thus ?clearing? the body of the virus.
But human immune systems take several days to weeks to mount an immune response, and people can get extremely sick (or die) in the meantime. During this infection, a person?s immune system makes antibodies that ?recognize? the virus, so that the next time he or she is infected with the same virus, he or she theoretically could mount a very rapid immune response. When a virus ?jumps? hosts, and an animal virus begins to infect humans, the proteins on the surface of the new virus are very different from the human viruses people are used to, and immune systems are even less able to offer protection.
To date, avian flu has appeared in Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, Vietnam, Russia, Turkey and Romania, with the flu crossing into the human population in many of those countries, notable among poultry farmers. There have been only rare instances of an infected person passing the avian flu virus to another person, and in those cases, the transmission has not been observed to continue beyond one person.
Scott says no one can predict when the avian flu virus may mutate in a way that would enable the virus to readily infect humans, and, more importantly, to be able to be transmitted from person to person. Such a mutation would create a new subtype of influenza A virus, and could result in a pandemic (worldwide spread). This could happen in six weeks, in six months, or six years. It?s not a question of if this will happen; it?s a question of when, she notes.
Currently there is no available vaccine to protect humans against the H5N1 virus, but vaccine development efforts are taking place. There are also antiviral medications that may help.