TIMELY TOPICS:

Newly Emerging Infectious Diseases
Avian Influenza (Bird Flu)

Howard G. McQuarrie, M.D.
Medical Director, PEHP

What is Avian Influenza?

Avian influenza or bird flu is a contagious disease caused by viruses that normally only effect birds and, less commonly, pigs. While all bird species are thought to be susceptible, domestic poultry flocks are especially vulnerable to infections that can rapidly reach epidemic proportions.

What is the present situation?

Since mid-December 2003, a growing number of Asian countries have reported outbreaks of pathogenic avian influenza in chickens and ducks. Infections in several species of wild birds have also been reported.

Outbreaks of Avian Influenza A (H5N1) have been confirmed, in poultry, in Cambodia, China, Hong Kong, Indonesia, Japan, Laos, South Korea, Thailand and Vietnam. It is strongly recommended that no exotic bird be imported from these countries or purchased in a pet store.

Particularly alarming, in terms of risks for human health, is the detection of a highly pathogenic type called, “H5N1,” as the cause of most of these outbreaks. The H5N1 strain has jumped the species barrier causing severe disease in humans, on two occasions in the recent past, and is gradually being seen in Vietnam and Thailand.

Public health officials are alarmed by the unprecedented number of outbreaks in poultry that have been reported. Most of the major occurrences of avian influenza recently acknowledged in Asia, have been caused by the H5N1 strain.

There is no evidence of humans contracting it from other humans. The World Health Organization (WHO) is actively involved in studies in Asia. It is reassuring that so few human cases have occurred to date.

There is not a vaccine effective against the H5N1 strain. However, there are two classes of drugs available for treating patients once they have been exposed. These are the M2 inhibitors (amantadine and rimantidine), and the neuraminidase inhibitors (oseltamivir and zanamivir). These have been licensed in some countries, and are thought to be effective regardless of the causative strain.

How are outbreaks contained?

The key to containing the outbreak is eliminating (killing) sick and exposed birds. Many experts believe this is crucial to averting more human cases.

What is the Center for Disease Control’s (CDC) current plan?

The CDC is working closely with the WHO and other partners in an effort to address the outbreak. So far, they have activated an emergency operations center and deployed technicians to Vietnam, as well as participating in a global influenza network.

CDC Recommendations

Travelers:

CDC advises that travelers to countries in Asia, with documented H5N1 outbreaks, should avoid poultry farms, contact with live animals in food markets, and any surfaces that appear to be contaminated with feces from poultry or other animals.

Health departments and healthcare professionals:

CDC has provided US Health Departments with interim guidance on enhanced surveillance and laboratory testing to help identify possible causes of H5N1 influenza that might be imported into the United States.

Testing for H5N1 is indicated for hospitalized patients with:

a. radiographically confirmed pneumonia, acute respiratory distress syndrome (ARDS), or other severe respiratory illness for which an alternative diagnosis has not been established, AND

b. history of travel within 10 days of symptom onset to a country with documented H5N1 avian influenza in poultry and/or humans. See the following web sites for current listings: http://www.oie.int/eng/en index.htm or WHO web site at http://www.who.int/en/

Testing for H5N1 should be considered on a case by case basis in consultation with state and local health departments for hospitalized or ambulatory patients with:

a. documented temperature of higher than 38 degrees C (100.4 degrees F), AND

b. one or more of the following: cough, sore throat, shortness of breath, AND history of contact with domestic poultry (e.g. visited a poultry farm, or a household raising poultry, or bird market) or a known or suspected human case of H5N1 in an H5N1-infected country within 10 days of symptom onset.

Important resources for more information:

Utah Epidemiology http://health.utah.gov/epi/

World Health Organization www.who.int/en/

Center for Disease Control http://www.cdc.gov/flu/avian/index.htm PEHP

Also see the Timely Topics Archive

Other Valuable Health Resources

• The book: Health Tracks, A Practical Guide to Managing Your Health (PEHP) – available from your employer/Human Resource Department or through this website.
• There is now new and updated information regarding cholesterol, and how it relates to coronary artery disease and its associated risk factors. This important information is covered in the article below (in Adobe Acrobat format). This copyright-free document has been produced by the National Cholesterol Education Program, and released by the National Institutes of Health (NIH). It is in an easy-to-read and understand format, and is recommended for everyone.