Offense good defense against bird flu

Posted on Mon, Jul. 10, 2006

Best precaution against avian flu is to be informed

Avian influenza has become a hot topic, resulting in a great deal of discussion about its possible impact. This includes speculation about the potential of an avian flu pandemic.

Avian flu refers to a group of viruses that most commonly infect only birds. These pathogens are usually quite species specific, but on rare occasion, they have crossed the species barrier to infect humans.

Wild birds all over the world carry these viruses in their intestines, but they usually do not get sick from them. The viruses are very contagious among birds though. The virus can make domesticated birds such as turkeys, chickens and ducks very sick, often resulting in death.

Influenza A viruses comprise many subtypes with some particularly more devastating than others. The H5N1 avian influenza A virus is one of the more deadly of the subtypes. Since 2003, more than 150 million birds died from the H5N1 virus or were euthanized to prevent further spread, the World Health Organization reported.

Of the few avian-influenza viruses that have crossed the species barrier to humans, H5N1 has caused the largest number of cases of severe disease and death. Unlike normal seasonal influenza, avian influenza has proven to have an aggressive clinical course, with rapid deterioration and high mortality rates. According to WHO, as of January, there were 139 confirmed cases of avian influenza in humans resulting in 71 deaths.

Infection in humans is most commonly the result of direct contact with infected poultry or surfaces or other objects contaminated with bird feces containing the virus. Instances of human-to-human transmission of H5N1 and other avian-influenza viruses have occurred only rarely, and transmission beyond first-generation contacts has not been documented.

So far, the risk of human infection is considered low, but scientists warn that mutations in the virus may increase the transmission rate. Because these viruses do not typically infect humans, there is little or no immunity or protection against them. If the H5N1 virus were able to infect people and spread easily from person to person, an influenza pandemic or worldwide outbreak would occur.

Signs and symptoms of avian influenza in humans are nonspecific, including fever, cough, sore throat and muscle aches, but more serious symptoms are known, such as conjunctivitis, pneumonia and acute respiratory distress.

Presently, four antiviral drugs are FDA approved for treatment of influenza. They all maintain activity against influenza A viruses. However, with the flu's possible mutations, resistant strains invariably will develop. In fact, analysis of some of the H5N1 viruses isolated from poultry and humans in Asia have shown the viruses to be resistant to two of the medications.

Health-care workers can protect their patients, themselves and their families by strictly adhering to familiar precautionary measures. For any patient being seen with fever, respiratory symptoms and a history of intercontinental travel, it is imperative to employ standard contact and airborne precautions until another diagnosis is made or laboratory tests rule out avian influenza.

Use of personal protective equipment such as gowns, goggles or face shields should be considered mandatory when treating these patients. Dedicated equipment should be used, such as disposable blood-pressure cuffs, thermometers and stethoscopes.

Brian Johnson is a registered nurse in the medical/surgical intensive-care units at Mount Nittany Medical Center.