Highly Pathogenic Avian Influenza in Thailand - THAILAND - This is a Follow-up report (No. 1) via OIE on the recent outbreak of Avian Influenza in Thailand.

See also: 6 February 2004, 23 January 2004

Information received on 6 February 2004 from Dr Yukol Limlamthong, Director General, Department of Livestock Development, Ministry of Agriculture and Cooperatives, Bangkok:

End of previous report period: 30 January 2004 (see Disease Information, 17 [6], 27, dated 6 February 2004).

End of this report period: 6 February 2004.

New outbreaks: a further eight provinces have been affected.

Map showing the infected districts

Total number of birds destroyed (23 January - 5 February 2004): 26,427,548.

Diagnosis:

A. Diagnostic tests used:

- haemagglutination inhibition test;

- agar gel precipitation test;

- virus isolation;

- intravenous pathogenicity index test.

Positive results were obtained between 31 January and 3 February 2004; 75,625 samples were tested, of which 161 were positive.

B. Causal agent: highly pathogenic avian influenza virus type A, subtype H5N1, closely related to human isolates from Vietnam (see below, the report from the University of Hong Kong).

Preliminary report on viruses AIV1/04 and AIV2/04, University of Hong Kong, Hong Kong, Special Administrative Region of the People's Republic of China:

“The gene sequencing and phylogenetic analysis of these two virus isolates has been carried out for seven gene segments: PB2; PB2; haemagglutinin (HA), nucleoprotein (NP), neuraminidase (NA), matrix (M), non-structural gene (NS). The sequencing for the PA gene is still awaited.

The results indicate that the two viruses AIV1/04 and AIV2/04 are very closely related to the human virus isolates from Vietnam for all seven gene segments.

We have also carried out antigenic analysis by the haemagglutination inhibition test using

a) polyclonal antisera to A/HK/156/97, A/Goose/HK/437.4/99, A/Ck/HK/YU22/02, A/HK/213/03;

b) monoclonal antibodies CP24 and CP58.

The overall pattern of the haemagglutination inhibition test reactivity is similar to that of two human Vietnam viruses.”

Control measures during reporting period:

- stamping out;

- quarantine;

- movement control inside the country;

- screening;

- zoning.

Vaccination is prohibited.

Source: Office International des Epizooties - 13th February 2004