HHS and International Partners Publish a Research Study from Cambodia that Indicates a Low Frequency of Transmission of the H5N1 Strain of Avian Influenza from Poultry-to-Humans

September 8, 2006 – The Centers for Disease Control and Prevention (CDC), within the U.S. Department of Health and Human Services (HHS), has published the results of a retrospective study conducted in a Cambodian village to assess rates of transmission of the H5N1 strain of avian influenza from poultry-to-humans.  Researchers conducted poultry surveys and blood tests of residents within a 1-km radius of the household of a 28-year-old man infected with the H5N1 strain of avian influenza in March 2005.  According to the man’s family, chickens in his home began dying about a week before he became ill; he had plucked at least one chicken and eaten poultry that had been ill.  After a few days, the man entered a hospital in Phnom Penh, but died despite medical care.  Study of his tissue samples revealed infection with the H5N1 virus.

Officials identified 42 household flocks as infected from January through March 2005.  Researchers tested the villagers for H5N1 antibodies, and, despite frequent contact with poultry suspected of having H5N1 infection, none of the 351 study participants from 93 households had neutralizing antibodies to H5N1.  Neutralizing antibodies arise to fight a specific infection, and show evidence of disease where symptoms might not be obvious.  The researchers concluded that asymptomatic and mild, subclinical, H5N1 virus infections had not occurred in the population studied, despite the direct contact between people and poultry and poultry products.

The study was a collaborative effort between the HHS/ CDC; Cambodian Ministries of Health and Agriculture, Forestry and Fisheries; Institut Pasteur in Cambodia; the World Health Organization; the Public Health Department of the Hong Kong Special Administrative Region of the People’s Republic of China; and the Food and Agriculture Organization of the United Nations.

HHS/CDC published the study, entitled "Low Frequency of Poultry-to-Human H5N1 Virus Transmission, Southern Cambodia, 2005" in Emerging Infectious Diseases, Volume 12, Number 10-October 2006.

For more information:

• Low Frequency of Poultry-to-Human H5N1 Virus Transmission, Southern Cambodia, 2005  (U.S. Centers for Disease Control and Prevention)

Last revised: November 09, 2007