Low Frequency of Poultry-to-Human H5N1 Virus Transmission, S. Cambodia
Low Frequency of Poultry-to-Human H5N1 Virus Transmission, S. Cambodia
To understand transmission of avian influenza A (H5N1) virus, we conducted a retrospective survey of poultry deaths and a seroepidemiologic investigation in a Cambodian village where a 28-year-old man was infected with H5N1 virus in March 2005. Poultry surveys were conducted within a 1-km radius of the patient's household. Forty-two household flocks were considered likely to have been infected from January through March 2005 because >60% of the flock died, case-fatality ratio was 100%, and both young and mature birds died within 1 to 2 days. Two sick chickens from a property adjacent to the patient's house tested positive for H5N1 on reverse transcription-PCR. Villagers were asked about poultry exposures in the past year and tested for H5N1 antibodies. Despite frequent, direct contact with poultry suspected of having H5N1 virus infection, none of 351 participants from 93 households had neutralizing antibodies to H5N1. H5N1 virus transmission from poultry to humans remains low in this setting.
From its identification in poultry in the People's Republic of China in 1996 and outbreak among commercial farms and live poultry markets in Hong Kong in 1997, highly pathogenic avian influenza A (H5N1) virus has become an unprecedented epizootic and spread to domestic poultry and wild bird populations in Asia, the Middle East, Europe, and Africa. This epizootic has affected farmers and the agricultural industry, claimed human lives, and raised the specter of a global influenza pandemic, perhaps even beyond the scale of the devastating 1918 "Spanish" influenza pandemic.
In Cambodia, highly pathogenic H5N1 was first reported in poultry in January 2004. Of 92 poultry outbreaks that year, 15 were confirmed by isolation of H5N1 viruses. During the first 4 months of 2005, 4 fatal human H5N1 cases were detected in Kampot Province, southeast Cambodia. These human cases occurred contemporaneously with unreported outbreaks of high deaths among chicken flocks throughout Kampot Province. However, H5N1 virus was confirmed in both a person and poultry in only 1 area of Kampot Province, a village in Banteay Meas District, ≈20 km from the Vietnam border and 15 km from the household of the first confirmed human H5N1 case-patient in Cambodia.
The patient from Banteay Meas District was a 28-year-old male farmer in whom a low-grade fever and dizziness developed on March 17, 2005. Approximately 1 week before he became sick, chickens at his home suddenly began dying. His family reported that he plucked at least 1 chicken and ate poultry that had died of illness suggestive of H5N1 disease. He may also have collected dead birds. On the third day of his illness, nonproductive cough, shortness of breath, and watery diarrhea developed. Two days later, he was transported to a Phnom Penh hospital. His condition rapidly deteriorated, and he died the next day despite mechanical ventilation and inotropic support. H5N1 virus infection was confirmed by reverse transcriptase (RT)-PCR from blood; tracheal aspirates; and nasopharynx, throat, and rectal swab specimens collected during his hospitalization (Institut Pasteur - Cambodia, unpub. data).
The farmer's rural village provided a setting in which we could study the epidemiologic features of H5N1 virus in poultry and humans. We report results of a retrospective study of poultry deaths and an H5N1 antibody seroepidemiologic investigation among residents of this village in Banteay Meas District, Kampot Province, Cambodia.
Abstract and Introduction
Abstract
To understand transmission of avian influenza A (H5N1) virus, we conducted a retrospective survey of poultry deaths and a seroepidemiologic investigation in a Cambodian village where a 28-year-old man was infected with H5N1 virus in March 2005. Poultry surveys were conducted within a 1-km radius of the patient's household. Forty-two household flocks were considered likely to have been infected from January through March 2005 because >60% of the flock died, case-fatality ratio was 100%, and both young and mature birds died within 1 to 2 days. Two sick chickens from a property adjacent to the patient's house tested positive for H5N1 on reverse transcription-PCR. Villagers were asked about poultry exposures in the past year and tested for H5N1 antibodies. Despite frequent, direct contact with poultry suspected of having H5N1 virus infection, none of 351 participants from 93 households had neutralizing antibodies to H5N1. H5N1 virus transmission from poultry to humans remains low in this setting.
Introduction
From its identification in poultry in the People's Republic of China in 1996 and outbreak among commercial farms and live poultry markets in Hong Kong in 1997, highly pathogenic avian influenza A (H5N1) virus has become an unprecedented epizootic and spread to domestic poultry and wild bird populations in Asia, the Middle East, Europe, and Africa. This epizootic has affected farmers and the agricultural industry, claimed human lives, and raised the specter of a global influenza pandemic, perhaps even beyond the scale of the devastating 1918 "Spanish" influenza pandemic.
In Cambodia, highly pathogenic H5N1 was first reported in poultry in January 2004. Of 92 poultry outbreaks that year, 15 were confirmed by isolation of H5N1 viruses. During the first 4 months of 2005, 4 fatal human H5N1 cases were detected in Kampot Province, southeast Cambodia. These human cases occurred contemporaneously with unreported outbreaks of high deaths among chicken flocks throughout Kampot Province. However, H5N1 virus was confirmed in both a person and poultry in only 1 area of Kampot Province, a village in Banteay Meas District, ≈20 km from the Vietnam border and 15 km from the household of the first confirmed human H5N1 case-patient in Cambodia.
The patient from Banteay Meas District was a 28-year-old male farmer in whom a low-grade fever and dizziness developed on March 17, 2005. Approximately 1 week before he became sick, chickens at his home suddenly began dying. His family reported that he plucked at least 1 chicken and ate poultry that had died of illness suggestive of H5N1 disease. He may also have collected dead birds. On the third day of his illness, nonproductive cough, shortness of breath, and watery diarrhea developed. Two days later, he was transported to a Phnom Penh hospital. His condition rapidly deteriorated, and he died the next day despite mechanical ventilation and inotropic support. H5N1 virus infection was confirmed by reverse transcriptase (RT)-PCR from blood; tracheal aspirates; and nasopharynx, throat, and rectal swab specimens collected during his hospitalization (Institut Pasteur - Cambodia, unpub. data).
The farmer's rural village provided a setting in which we could study the epidemiologic features of H5N1 virus in poultry and humans. We report results of a retrospective study of poultry deaths and an H5N1 antibody seroepidemiologic investigation among residents of this village in Banteay Meas District, Kampot Province, Cambodia.
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