even as India is trying to build a firewall to block out the bird flu virus, the first likely case of the deadly pathogen's human-to-human transmission has surfaced in Vietnam. Two siblings in Hanoi are suspected to have contracted the disease from their brother. All three have succumbed to the infection. The total confirmed toll has now reached 12, out of which nine people have died in Vietnam and three in Thailand.

The latest development has heightened fears regarding the disease, which is decimating poultry flocks in several parts of Asia. It is estimated that as many as 25 million birds have been culled since the epidemic broke out in South Korea in mid-December last year. The form of bird flu, caused by the avian influenza (ai) virus subtype h5n1, has already spread to areas such as Thailand, Indonesia, China, Cambodia and Laos.

Closer to India, Pakistan has culled about 3.5 million birds in Karachi. The ai strains detected there were, however, of the less virulent h7 and h9 varieties. Nonetheless, India has banned all imports of poultry as well as processed poultry products and also issued an alert against the disease.

Significantly, sources at the Indian Veterinary Research Institute, the premier poultry and livestock laboratory in the country, have now conceded that a low-pathogenic ai virus belonging to the h9 family was isolated from a few samples in Haryana last May (see: