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JAKARTA, May 14 (Reuters) - A pregnant Indonesian woman from Sumatra island has died of bird flu, increasing the country"e;s human death toll from the disease to 76, health officials said.

Two tests had confirmed the 26-year-old woman, who died on Saturday evening in Medan, had the H5N1 bird flu virus, Runizar Ruesin, head of the health ministry"e;s bird flu centre, said by telephone on Monday.

The woman had been suffering from fever and respiratory problems when she was hospitalised on May 8.

Surya Dharma of the North Sumatra health agency said on Sunday that the woman, who was four months pregnant, had been in contact with dead fowl.

Three out of the five chickens her family had and two pigeons died suddenly two weeks ago, said the official. The family burned the dead birds, but ate the remaining chickens.

"The family slaughtered the rest of the chickens, cooked and ate them," Dharma said by telephone, adding that a team had been sent to investigate whether anyone else in the family could have been infected.

The official was speaking before the result of the second test.

Indonesia has the highest human death toll from the disease in the world.

The virus is endemic among fowl in many parts of Indonesia, where millions of people keep a few chickens or other domesticated birds in their yards.

Although avian flu still mainly affects birds, experts fear if the H5N1 strain mutates into a form easily transmitted from person to person, it could sweep the world, killing millions.