When it comes to public health issues, there is a razor-thin line between appropriate caution and overcompensatory alarm. Such is the case with avian influenza, more commonly known as bird flu. University of Arkansas professor Dustan Clark, a veterinarian, participates in an avian influenza advisory group that meets regularly to assess developments and potential threats, and offers these reminders to those concerned about potential flu pandemics.
“The best thing to remember is that there are public health physicians, veterinarians, and other individuals out there that are keeping up with what is going on with the disease in other involved countries,” explained Clark. “If there was to be a serious problem, the mechanism is in place to do something to handle it very quickly.”
Recent media articles, such as that in The New York Times magazine, have sounded alarms and prompted concerns about the possibility of avian influenza becoming the next pandemic to affect the U.S. and other developed and undeveloped nations, Clark said.
Clark says that in any given year, the wild waterfowl and shorebird populations have various avian influenza viruses. The viruses usually are not a problem in these wild birds, but they can be a problem in domestic poultry.
Worldwide, there are many strains of the avian influenza virus that cause varying degrees of illness in poultry. Most of those viruses are classified as “low pathogen” and cause few, if any, signs of illness in fowl. The problem develops when those viruses mutate into highly pathogenic viruses and cause severe losses in poultry. Typically, avian influenza viruses that affect poultry and other birds do not affect people.
However, in 1997 an avian influenza virus (H5N1) did infect both poultry and a few people in Hong Kong. This was the first known instance of the avian influenza virus being transmitted directly from birds to people and causing severe illness and death. Since 1997 there have been a few other instances of the avian influenza virus causing illness or death in people.
The majority of the human cases have happened with people that were closely associated with affected poultry. Influenza viruses constantly mutate, and epidemiologists are concerned that the avian influenza virus could infect a person who has a human influenza strain, creating a new mutant flu strain to develop that could spread easily from person to person.
The U.S. grappled during the fall with a shortage of vaccines for human influenza. When it comes to poultry, however, vaccination is the remedy of last resort. Regarding avian influenza, the best method of prevention is what is known as biosecurity, or monitoring and controlling disease in the poultry population before it becomes dangerous to humans.
Clark, a veterinarian, says that while a human flu vaccine might help prevent avian flu, the best preventative is caution. People who travel abroad and visit poultry and livestock herds should take cautionary measures such as avoiding close contact with the animals and destroying or sanitizing clothing worn on the visits.
“Most diseases don’t cross species,” said Clark. “In the human population, the best preventative for disease is good sanitation and biosecurity. It’s a matter of risk assessment. The greater percentage of the population that practices biosecurity, or that receives a human flu vaccine, the less chance we have of avian influenza infecting a person that has human influenza. Thus there is a reduction in the threat of a new influenza mutant developing from a combination of the avian and human types and subsequently developing into a pandemic.”
There have been three pandemics in the 20th century, the worst of which was the Spanish flu pandemic of 1918-19. In recent years, however, a handful of people have died from avian flu in developing countries such as Vietnam and Thailand. Clark reiterates, however, that the current risk to the human population is very small.
“Historically, we have not had documentation of the flu spreading from birds to people. That changed a few years ago with the 1997 outbreak in Hong Kong that later proved to be a form of AI that mutated and spread to cause human disease,” he said.
The last known human avian influenza infection was in Vietnam in March 2004, but the number of new human infections sputtered and then appeared to have ceased. Now, medical and veterinary experts believe for a true new pandemic to develop, it would take an entirely new human influenza subtype to emerge, one to which people have never been exposed and to which they would not have immunity. While this remains a frightening possibility, most experts believe avian influenza in humans is not a serious threat.
“Still, if there is any suspicion of avian flu in a poultry flock in this country, the flock would be quickly destroyed, and we believe that would almost always control the threat of spread to humans,” Clark said. “The problem is that this is not always what has happened in developing countries.”
For the general population, Clark advises logical preventative measures after potential exposure. “There is no need for alarm or panic in the general population,” said Clark. “Numerous health professionals are monitoring influenza; and, training, surveillance and education efforts continue. Plans for dealing with an influenza emergency have been developed and are continually updated so that the best control efforts available could be implemented should the need arise.”