JAKARTA, Oct 11 (Reuters) - A 12-year-old Indonesian boy has tested positive for bird flu, and is being treated in a Jakarta hospital, a health ministry official said on Thursday.

The ministry"e;s bird flu centre"e;s Muhammad Nadirin said it was not clear how the boy from Tanggerang city in West Java, contracted the virus, but some chickens had died in his neighbourhood.

The most common way to contract the deadly virus is through sick fowl.

The disease is endemic in the bird population in most parts of Indonesia, where millions of backyard fowl are kept in close proximity to humans and where education campaigns often do not reach remote areas.

Muchtar Ichsan, a doctor at the hospital, said the boy has been taken to an isolated room and was on a respiratory device.

Indonesia has 109 confirmed cases of human bird flu, 87 of them fatal, the highest in the world.

Scientists are concerned the H5N1 virus could mutate into a form that passes easily between humans, triggering a pandemic in which millions could die.