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28 January 2004 CDC Issues Fact Sheet on Asian Avian Flu StrainCDC works with international health officials to evaluate outbreak The U.S. Centers for Disease Control and Prevention is working with international health officials to evaluate the outbreak of avian flu occurring in Asia, resulting in some human deaths. Millions of poultry have been killed in order to contain the disease. CDC issued a fact sheet on the disease January 27. H5N1: This is the designation for the strain of influenza virus that is being transmitted from birds to humans. The letters "H" and "N" stand for haemagglutinin and neurominidase, two proteins found in the molecule of the influenza virus. These proteins combine in different ways as the cells mutate, creating different strains of the disease with variable properties. Health officials believe there is evidence that the H5N1 has a unique capacity to jump the species barrier and cause serious and sometimes fatal disease in humans. Following is the CDC fact sheet: (begin text) U.S. Centers for Disease Control and Prevention Recent Influenza A(H5N1) Cases The Government of Vietnam has reported hospitalized cases of severe respiratory illness in people from provinces surrounding Hanoi beginning in October 2003. Avian influenza A(H5N1) virus infections have been confirmed in some of these patients. Deaths have been reported. Visit http://www.who.int/en/ for updated case counts. Influenza A(H5N1) viruses normally circulate among wild birds but can infect poultry and rarely have infected people in the past. In 1997, 18 persons in Hong Kong were hospitalized because of influenza A(H5N1) infections and six of them died. In 2003, two residents of Hong Kong who traveled to China developed influenza A(H5N1) virus infections and one of them died. In Vietnam, large outbreaks of influenza A(H5N1) have been reported among poultry in the southern and northern regions of the country. The World Health Organization (WHO) has reported that the H5N1 strain implicated in the outbreak has been sequenced. All genes are of avian origin, indicating that the virus has not acquired human genes. The acquisition of human genes increases the likelihood that a virus of avian origin can be readily transmitted from one human to another. On January 23, 2004, WHO reported two laboratory-confirmed cases of H5N1 avian influenza in children in central Thailand. The first case is in a 7-year-old boy from Suphanburi province who developed fever and cough on January 3; his illness progressed to acute respiratory distress syndrome on January 13. The second case is a 6-year-old boy from Kanchanaburi province who developed fever on January 6, followed a week later by severe pneumonia with acute respiratory distress syndrome. As of January 25, 2004, both patients were alive. More information on this report is available at http://www.who.int/en/. H5N1 Outbreak Investigation WHO is coordinating an investigation in Vietnam. Staff from CDC have traveled to Vietnam to work with WHO and Vietnam's human and animal health authorities to evaluate the situation, including patterns of transmission of the influenza A(H5N1) viruses. The investigation will focus on determining specific characteristics of influenza A(H5N1) viruses isolated from human cases and poultry and on determining how people became infected. In addition, increased surveillance will help investigators determine how many people in Vietnam already have been infected with the influenza A(H5N1) virus and whether other people are continuing to be infected. WHO will be collaborating closely with health authorities in Thailand in responding to the situation there. H5N1 Infections Among Poultry in Asia Outbreaks of avian influenza A(H5N1) have been reported among poultry in Vietnam, South Korea, Thailand, Japan, Indonesia, Myanmar, Cambodia, and China. H5N1 has been confirmed in smuggled birds in Taiwan, but not in wild flocks or poultry. Additionally, there have been reports of poultry deaths in Laos and Pakistan. Influenza A(H5N1) Outbreak (continued from previous page) CDC Recommendations U.S. residents who are traveling outside the United States should consult their physician for advice about which vaccines they should obtain. In Vietnam and in other tropical regions, influenza can occur at any time during the year. Thus, persons who are at increased risk of developing influenza-related complications and healthy persons who wish to decrease their risk of becoming ill with influenza should receive the 2003-04 trivalent influenza vaccine. The vaccine will protect against three viruses and offers some protection against variants of them as well. At this time CDC and WHO have not issued any travel alerts or advisories for the region in response to the H5N1 outbreak. However, travelers to countries in Asia with documented H5N1 outbreaks are advised to avoid poultry farms, contact with animals in live food markets and any surfaces that appear to be contaminated with feces from poultry or other animals. For more information about topics related to travelers' health, visit http://www.cdc.gov/travel/. Enhanced U.S. Influenza Surveillance At this time, CDC recommends enhanced surveillance efforts by state and local health departments, hospitals, and clinicians to identify patients who have been hospitalized with unexplained pneumonia, ARDS, or severe respiratory illness AND who have traveled to countries in Asia with documented H5N1 outbreak. CDC will make additional recommendations on enhanced surveillance if influenza A(H5N1) activity continues to evolve. More Information About Influenza For further details about the reported cases of influenza A(H5N1) in Vietnam, see the WHO Web site http://www.who.int/en/. Additional information about influenza is available on the CDC Web site at http://www.cdc.gov. (end text) |
