The Pulse

This SPECIAL REPORT focuses on Bird Flu, one of the most serious emerging health threats facing the world today. The information contained in this SPECIAL REPORT deals with an ongoing and rapidly changing current event. Check back often for the very latest information.

Current Situation

Outbreaks of avian influenza A (H5N1) among poultry are ongoing in several countries in Asia, including Thailand, Vietnam, and Cambodia. Reports of sporadically occurring human cases of influenza A (H5N1) continued through January 2005. Thailand reported five human cases of influenza H5N1 (with four deaths) in September and October 2004, but no additional cases to date. Thirteen human cases of influenza A (H5N1) infection (with 12 deaths) have been reported by Vietnam since mid-December 2004; WHO has reported that 10 of these cases (with 9 deaths) have been confirmed.

One instance of probable limited human-to-human transmission of influenza A (H5N1) virus was reported in Thailand between a child and her mother and aunt in September 2004. Health authorities in Vietnam are investigating two possible instances of limited human-to-human transmission in family clusters. One instance involves two brothers in Vietnam with confirmed influenza A (H5N1) infections; a third brother was hospitalized for observation only and did not become ill. In the second instance, a daughter developed symptoms within 6 days of her mother’s onset of illness, which was confirmed as influenza A (H5N1). Investigations are exploring possible sources of exposure and looking for other signs of illness in family members, other close contacts, and the general community.

In addition, the first human case of influenza H5 infection in Cambodia has been confirmed in a woman who was hospitalized in Vietnam and died. A joint mission between the Cambodian Ministries of Health and Agriculture and WHO is in Cambodia investigating the circumstances surrounding this case.

As of February 4, 2005, the cumulative number of confirmed human cases of influenza A (H5N1) reported in Asia since January 28, 2004, is 55 cases (with 42 deaths), according to WHO. This total includes the case from Cambodia .

The avian influenza A (H5N1) epizootic in Asia poses an important public health threat, and CDC is in communication with WHO and will continue to monitor the situation. The epizootic in Asia is not expected to diminish substantially in the short term, and it is likely that influenza A (H5N1) infection among birds has become endemic to the region and that human infections will continue to occur. So far, no sustained humanto- human transmission of the influenza A (H5N1) virus has been identified, and no influenza A (H5N1) viruses containing both human and avian influenza virus genes, indicative of gene reassortment, have been detected.

Travel Health Precaution

On January 26, 2005, CDC issued a Travel Health Precaution notice about avian influenza A (H5N1). This notice is directed at travelers who may be returning from Vietnam to visit family and friends, especially during the upcoming holiday, and who may be at greater risk for exposure to poultry through food preparation or at farms and bird markets where infected poultry may not be readily detected. The notice outlines specific measures for travelers to take before, during, and after travel to Vietnam. CDC has not recommended that the general public avoid travel to any countries affected by influenza A (H5N1). For more information, see CDC’s Travelers’ Health website.

What is CDC doing to prepare for a possible H5N1 flu pandemic?

CDC is taking part in a number of pandemic prevention and preparedness activities, including:
· Working with the Association of Public Health Laboratories on training workshops for state laboratories on the use of special laboratory (molecular) techniques to identify H5 viruses.
* Working with the Council of State and Territorial Epidemiologists and others to help states with their pandemic planning efforts.
* Working with other agencies such as the Department of Defense and the Veterans Administration on antiviral stockpile issues.
* Working with the World Health Organization (WHO) and Vietnamese Ministry of Health to investigate influenza H5N1 in Vietnam and to provide help in laboratory diagnostics and training to local authorities.
* Performing laboratory testing of H5N1 viruses.
* Starting a $5.5 million initiative to improve influenza surveillance in Asia.
* Holding or taking part in training sessions to improve local capacities to conduct surveillance for possible human cases of H5N1 and to detect influenza A H5 viruses by using laboratory techniques.
* Developing and distributing reagents kits to detect the currently circulating influenza A H5N1 viruses.
* Working together with WHO and the National Institutes of Health (NIH) on safety testing of vaccine seed candidates and to develop additional vaccine virus seed candidates for influenza A (H5N1) and other subtypes of influenza A virus.

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

Is there a vaccine to protect humans from H5N1 virus?

There currently is no vaccine to protect humans against the H5N1 virus that is being seen in Asia. However, vaccine development efforts are under way. Research studies to test a vaccine to protect humans against H5N1 virus are expected to begin in April 2005. (Researchers are also working on a vaccine against H9N2, another bird flu virus subtype.) For more information about the H5N1 vaccine development process, visit the National Institutes of Health website.


In humans, it has been found that avian flu causes similar symptoms to other types of flu:
* fever
* cough
* sore throat
* muscle aches
* conjunctivitis
* in severe cases of avian flu, it can cause severe breathing problems and pneumonia, and can be fatal.

What is avian influenza (bird flu)?

Bird flu is an infection caused by avian (bird) influenza (flu) viruses. These flu viruses occur naturally among birds. Wild birds worldwide carry the viruses in their intestines, but usually do not get sick from them. However, bird flu is very contagious among birds and can make some domesticated birds, including chickens, ducks, and turkeys, very sick and kill them.

Do bird flu viruses infect humans?

Bird flu viruses do not usually infect humans, but several cases of human infection with bird flu viruses have occurred since 1997.

What are the symptoms of bird flu in humans?

Symptoms of bird flu in humans have ranged from typical flu-like symptoms (fever, cough, sore throat and muscle aches) to eye infections, pneumonia, severe respiratory diseases (such as acute respiratory distress), and other severe and life-threatening complications. The symptoms of bird flu may depend on which virus caused the infection.

How does bird flu spread?

Infected birds shed flu virus in their saliva, nasal secretions, and feces. Susceptible birds become infected when they have contact with contaminated excretions or surfaces that are contaminated with excretions. It is believed that most cases of bird flu infection in humans have resulted from contact with infected poultry or contaminated surfaces.

How is bird flu in humans treated?

Studies suggest that the prescription medicines approved for human flu viruses would work in preventing bird flu infection in humans. However, flu viruses can become resistant to these drugs, so these medications may not always work.

What is the risk to humans from bird flu?

The risk from bird flu is generally low to most people because the viruses occur mainly among birds and do not usually infect humans. However, during an outbreak of bird flu among poultry (domesticated chicken, ducks, turkeys), there is a possible risk to people who have contact with infected birds or surfaces that have been contaminated with excretions from infected birds. The current outbreak of avian influenza A (H5N1) among poultry in Asia (see below) is an example of a bird flu outbreak that has caused human infections and deaths. In such situations, people should avoid contact with infected birds or contaminated surfaces, and should be careful when handling and cooking poultry. For more information about avian influenza and food safety issues, visit the World Health Organization website.


* Wikipedia: Avian influenza
* World Health Organization: Avian influenza-fact sheet
* Avian influenza faq's
* CDC - Latest info update march 8,2005
* CDC - Pandemics
* More about Bird Flu from GoldBamboo