Investigation of surveillance on human infection with avian influenza in Guangzhou in 1997 to 2006

Objective To understand the epidemiological features of human infections with avian influenza for those working in the avian breeding,sales and slaughtering at locations with potentially high epidemics of human case of avian influenza infections.Methods Serum samples were collected from human volunteers with high risk to avian influenza infection.Antibodies specific to avian influenza were tested by micro hemagglutination inhibition assay.Epidemiologieal analysis was conducted on cases potentially infected with H9N2 or H5N1.Results The H9 infection rate among the occupational group dealing with poultry in Guangzhou was 4.56%(0.51%～10.00% )for the perind studied in this report.There was no significant difference among various age groups.One porson infected with avian influenza A(H5N1)at Cuangzhou in 2006 had traveled to multiple live poultry markets before the onset of disease.A poultry slaughterer working in one of these live poultry market had positive anti-H5N1 antibody responses.On the other hand,one person with positive anti-H5N1 and one patient with positive anti- H9N2 did not have history of direct poultry contact.Conclusion H5N1 and H9N2 may cause asymptomatic infections in humans.Beside persons working directly in poultry farms,those involved in avian breeding,sales and slaughtering are also at high risk for avian influenza infection.