A cross-sectional study was conducted to determine the avian influenza A/H5Nl antibody positive among persons who slaughter and sell poultry in three provinces for 4 months (September-December, 2011), The data was collected by face-to-face interview method using a structured questionaire and collected 3-5ml intravenous blood sample to perform laboratory tests by hemagglutination inhibition (HAI) and microneutralization (MN) assay techniques. Results showed that an overall antibody positive proportion was 6.1 percent in accordance with World Health Organization laboratory confirmation guidelines. The proportions in Ha Noi, Thai Binh and Thanh Hoa provinces were 7.2 percent, 5.3 percent and 4.5 percent, respectively
no significant difference between male and female
the highest positive proportion was among group of 25-35 years old (8.0 percent)
family member was at the highest proportion (16.7 percent) and people who live in the family with average monthly income from 3-5 millions VND at the highest of 9.1 percent.