Outbreak Notice
Update on Avian Influenza, Asia
(Updated October 8, 2004; September 16, 2004; August 14, 2004; July 14, 2004; Released April 23, 2004)

According to the World Health Organization (WHO), health authorities in Thailand have recently reported three new confirmed human cases of influenza A (H5N1). The most recent case was in an 8- or 9-year-old girl from the northern province of Phetchabun who died of severe respiratory disease on October 3, 2004. Prior to onset of illness, she had direct contact with diseased chickens that had died. Two additional confirmed H5N1 cases were identified among a family cluster of four individuals who were ill. One confirmed case-patient, a 26-year-old woman, died on September 20. The other confirmed case-patient is the deceased woman’s 32-year-old sister, who remains hospitalized in stable condition. The index case-patient was an 11-year-old girl who died of pneumonia on September 8. She was the daughter of the 26-year-old deceased patient but lived with her aunt (the 32-year-old patient) in Kamphaeng Phet, a northern province of Thailand. Both the girl and her aunt had a history of exposure to dead chickens. The mother of the 11-year-old girl lived in Bangkok and had no history of exposure to sick or dead poultry. She traveled to Kamphaeng Phet to care for her hospitalized daughter. The fourth patient in the family cluster, the 6-year-old son of the aunt, has been discharged from the hospital.

Because specimens from the index case-patient were not available for laboratory confirmation, her case has been classified as probable H5N1 infection. Specimens from the 6-year-old boy are being tested. Evidence suggests person-to-person transmission of H5N1 virus may have occurred between the index case-patient and her mother. Outside this family cluster, there is no current evidence of person-to-person transmission. In response to the situation in Thailand, government and local health authorities have enhanced surveillance in hospitals and communities throughout the affected provinces.

Since January 2004, a total of 16 human H5N1 cases in Thailand have been confirmed; 11 have been fatal. During the same period, Vietnam reported 27 human H5N1 cases, of which 20 have been fatal. Most confirmed H5N1 cases have been among children and young adults who had exposure to sick or dead poultry. Both countries have been working closely with WHO to strengthen surveillance for human cases of H5N1 and to implement control and preparedness activities. The Centers for Disease Control and Prevention (CDC) remains in close communication with WHO about the evolving avian influenza situation in Asia and has been assisting with laboratory testing for H5N1.

Avian influenza A (H5N1) is a serious viral infection that occurs primarily among poultry and other birds. While it is unusual for humans to acquire influenza virus infections directly from poultry or birds, rare human infections and outbreaks caused by certain avian influenza A viruses have been documented since 1997. During mid-January 2004 through March 2004, widespread H5N1 outbreaks among poultry were reported from Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam. To date, efforts to contain the outbreaks have included culling more than 100 million poultry. At that time, Thailand and Vietnam also reported human infections and deaths caused by H5N1 viruses (for details, see http://www.who.int/csr/disease/avian_influenza/en/). All patients with confirmed H5N1 were severely ill, and many had a history of exposure to sick or dead poultry. Field investigations at that time showed no conclusive evidence of human-to-human transmission of the disease.

Beginning in late June 2004, renewed outbreaks of H5N1 among poultry were reported in Indonesia, Malaysia, Vietnam, and Thailand. Although the previous H5N1 poultry outbreaks in Japan and South Korea have been controlled, the degree to which outbreaks in Cambodia, China, Indonesia, Laos, Malaysia, Thailand, and Vietnam have been controlled is uncertain. For this reason, CDC continues to recommend to health-care providers the measures that were detailed in a health update on August 12, 2004 (http://www.cdc.gov/flu/avian/professional/han081304.htm), which specifies enhanced surveillance for suspected H5N1 cases among travelers with severe unexplained respiratory illness returning from H5N1-affected countries. CDC also remains in communication with WHO about the avian influenza outbreaks.

Travelers to Cambodia, China, Indonesia, Laos, Malaysia, Thailand, and Vietnam are advised to follow standard health recommendations for Southeast and East Asia and, as a precaution, to avoid places such as poultry farms and bird markets where live poultry are raised or kept, and avoid contact with sick or dead poultry. As with other infectious illnesses, one of the most important preventive practices is careful and frequent handwashing. Cleaning your hands often using either soap and water or waterless, alcohol-based hand rubs removes potentially infectious materials from your skin and helps prevent disease transmission.  Travelers returning with an illness from any area of the world are reminded to seek prompt medical attention.

For more information about CDC’s health recommendations for travel to Asia, see http://www.cdc.gov/travel/seasia.htm and http://www.cdc.gov/travel/eastasia.htm.

For information about avian influenza health updates, see http://www.cdc.gov/flu/avian/professional/han081304.htm.

For information about previous avian influenza outbreaks, see http://www.cdc.gov/flu/avian/facts.htm.

For more information on recent studies about avian influenza, see http://www.who.int/csr/don/2004_07_08/en/.

For information about the embargo on the importation of birds from specified Southeast Asian countries, see http://www.cdc.gov/flu/avian/outbreaks/embargo.htm.

For information on influenza, see http://www.cdc.gov/flu/.