The head of World Health Organization says Severe Acute Respiratory Syndrome will continue to challenge global health care if its source is not identified and eliminated. But scientists at a conference in Kuala Lumpur say the disease is not likely to be eradicated.

The World Health Organization's director general says Severe Acute Respiratory Syndrome is similar to AIDS in that it will continue to pose new challenges if its source is not eradicated.

"We are up for new challenges, even in the future, and therefore the capacity to identify and react and respond is so important," commented Gro Harlem Bruntland at the end of a two-day WHO conference in Kuala Lumpur.

The source of SARS is still unknown, but there is evidence the virus may have come from wild animals, including the civet, a mammal sold as a culinary delicacy in southern China.

Some researchers think civets could be the source of future SARS outbreaks. They say the virus likely jumped from its host animal to a human preparing the civet for eating.

Veterinary epidemiologists, who are scientists who trace infectious disease in animal populations, say SARS eradication is unlikely.

"The question of can SARS be eradicated, and we concluded that it was to early to say, but certainly all the indications so far is that ? such eradication would be extremely difficult," Dr. Hume Field of the Animal Research Institute of Australia.

Other scientists at the SARS conference had different conclusions.

One doctor says the threat of SARS reemerging could be greatly reduced if transmission between people and animals could be permanently cut.

The executive director of the WHO, David Heymann, indicated the U.N. agency is still optimistic the new disease can be eliminated.

SARS, which causes a serious pneumonia, first emerged in China late last year. Since then it has infected almost 8,500 people, killing more than 800.