Potential infections of H5N1 and H9N2 avian influenza do exist in Guangdong populations of China.
BACKGROUND
Southeast China is one of the sites of influenza origin. During 2003--2004, nine avian influenza outbreaks took place in Guangdong Province. But no human case was reported. To examine the status of potential human infection by human influenza (H1N1, H3N2) and avian influenza (H5N1, H7N7, H9N2) in the avian influenza epidemic area of Guangdong Province, China, we conducted a seroepidemiologic survey in the people of this area from April to June of 2004.


METHODS
Three out of 9 H5N1 avian influenza affected poultry areas in Guangdong were randomly selected, and the population living within 3 kilometers of the affected poultries were chosen as the survey subjects. One thousand two hundred and fourteen people were selected from 3 villages at random. Human and avian influenza antibody titers were determined by hemagglutination-inhibition (HI) test and microneutralization test (MNT).


RESULTS
The positive rate of antibody to H5N1 was 3.03% in the occupational exposure group and 2.34% in general citizens group; that of H9N2 was 9.52% in the occupational exposure group and 3.76% in the general citizens group. Moreover one case in the occupational exposure group was positive for H7N7. One year later, all previously positive cases had become negative except for one H5N1-positive case.


CONCLUSIONS
The observations imply that H5N1 and H9N2 avian influenza silent infections exist in Guangdong populations.
Lu
Ci-yong
CY
School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong 510080, China.
Lu
Jia-hai
JH
Chen
Wei-qing
WQ
Jiang
Li-fang
LF
Tan
Bing-yan
BY
Ling
Wen-hua
WH
Zheng
Bo-jian
BJ
Sui
Hong-yan
HY
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002645:Chickens; D002681:China / Q000453:epidemiology; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype; D053127:Influenza A Virus, H9N2 Subtype; D005585:Influenza in Birds / Q000453:epidemiology; D007251:Influenza, Human / Q000453:epidemiology*; D008875:Middle Aged; D009500:Neutralization Tests; D016273:Occupational Exposure