A World Health Organisation laboratory test has confirmed a 5-year-old Indonesian boy who died last month was infected with bird flu, a health ministry official said on Monday.

His death takes the total number of confirmed bird flu fatalities in the country to 40.

The victim died on June 16 in Tulungagung in East Java province after being admitted to hospital on June 8, I Nyoman Kandun, director general for communicable disease control at the health ministry, told Reuters.

The infection was confirmed to be from the H5N1 avian virus by a WHO laboratory in Hong Kong, he said.

An official at the health ministry’s bird flu centre who declined to be identified said: “There was a dead chicken near his house.”

The chicken cage was 15 metres (49 ft) from the boy’s home, the official added.

Indonesia has seen a steady rise in human bird flu infections and deaths since its first known outbreak of H5N1 in poultry in late 2003, and has registered more deaths this year than any other country.

Indonesia has 220 million people and an estimated 1.2 billion chickens, some 30 percent of them in the yards of homes in both rural and urban areas.

The bird flu virus is endemic in poultry in nearly all of the 33 provinces in Indonesia, a country of 17,000 islands sprawling across some 5,000 km (3,100 miles).

Despite the climbing death toll, the government has resisted mass culling of birds, saying it is too costly and impractical.

Vaccination has been preferred to culling, which has been done only sporadically at selective farms and their immediate surroundings.

Bird flu remains essentially an animal disease but many countries around the world are on alert over fears it may mutate into a disease that could pass easily among people and trigger a pandemic, killing millions.

Indonesia drew international attention in May when the virus killed members of a single family in North Sumatra. Experts said there could have been limited human-to-human transmission in this cluster case.

But they stressed genetic analyses of the virus have not shown all of the traits that are known so far to allow it to spread easily among people.