BEIJING (AFP) - The fight against contagious diseases is now a top priority after China’s massive earthquake, with the rotting carcasses of millions of dead animals adding to the dangers, officials said Saturday.

“Combating epidemics is the most urgent and the biggest task facing us right now,” Wei Chao’an, vice minister of agriculture, told a press conference.

He was speaking as millions of homeless residents of southwestern China faced an uncertain future living amid the rubble of Monday’s 7.9 earthquake, which left an estimated 50,000 people dead.

China’s health ministry has said it cannot rule out major epidemics in a zone where rudimentary sanitation and uncertain access to safe water and food supplies create a breeding ground for infectious diseases.

Water and food-borne bacteria and viruses are the main threat to public health in areas lacking basic facilities, such as cooking stoves and toilets, officials said.

China’s top veterinarian, Li Jingxing, said the rotting carcasses of 12.5 million livestock and poultry killed by the quake were also a major risk.

“For these carcasses we are adopting measures such as deep burial to ensure that no epidemics are caused,” said Li, who heads the veterinary department at the agriculture ministry.

He said contaminated carcasses could trigger the spread of diseases like avian influenza, encephalitis B and rabies, while the earthquake may also heighten the risk of infection of anthrax or tetanus.

The World Health Organisation (WHO) said that to avoid epidemics, the priority is to secure a clean supply of fresh drinking water and to improve food safety and sanitation standards.

“Unsafe food and lack of access to safe water, facilities for personal hygiene and safe sanitation arrangements, all create a real risk of outbreaks of infectious diseases,” said Arturo Pesigan, the WHO’s technical officer for emergency and humanitarian action in the western Pacific region.

He said the danger was raised by large numbers of people living in overcrowded temporary shelters.

Earlier, China’s Housing Minister Jiang Weixin said heavy water purification machines were in Sichuan province or headed to the region.

“We plan to send 48 portable water-purifying machines to the most badly hit areas,” he was quoted as saying, acknowledging that lack of clean water was a key health concern.

Jiang said air drops of millions of bottles of water to the quake-hit areas were insufficient and that water purifying machines were needed.

He said they were destined for Wenchuan and Beichuan counties, where water supplies had been cut off by the quake.

Forty machines were being transported from manufacturers to the quake zone, and two were already in Chengdu, the capital of Sichuan province, he said. Six more machines were believed to have reached there by late Friday.

Each machine can produce enough safe drinking water for up to 10,000 people, said Li Dongxu, head of the housing ministry’s urban construction department.