The Indian health care authorities have completed health checks on thousands of people after an outbreak of bird flu in the remote northeast, and cleared 4 boys who had been suffering from fever after handling dead or sick poultry.

Throat swab and tissue samples of the 4 boys had been sent for testing but no sign of bird flu was found. "They are negative,"

Vineet Chawdhry, a joint secretary in India's Health Ministry, told Reuters on Friday [3 Aug 2007]. Thousands of people in Manipur state in India's northeast were also checked by health officials after the outbreak of the H5N1 strain of bird flu in chickens on a small poultry farm.

Globally, the H5N1 virus has killed at least 192 people out of 319 who have been affected since late 2003, with health experts fearing it could one day mutate into a form that could pass easily between humans, triggering a pandemic.

In Manipur, the boys -- who media reports say are all under 14 -- lived within a 5-km [3.1-mile] radius of the affected farm. Another

21 people living or working on the farm and 9 veterinary workers were also tested and cleared earlier.

The Indian state shares a border with Myanmar [formerly Burna], where there have been multiple outbreaks of bird flu this year [2007], including two in July alone. Authorities in Manipur stopped culling operations on Thursday [2 Aug 2007] after killing and burying nearly 300 000 fowl.

But officials in Tripura, another northeastern state, were on alert against bird flu after around 300 chicken died in a district bordering Bangladesh, where avian flu has spread to a number of areas this year, infecting large numbers of poultry. An official in the state said chicken blood and tissue samples had been sent to a federal laboratory for testing.

India had 2 major outbreaks of the H5N1 virus in chickens last year [2006] in its western region but has not reported any human case yet.