Guangzhou, Jan. 6 (Reuters): Health workers began drowning and incinerating thousands of civet cats in southern China today over fears they carry a new strain of Sars, but international experts worried the cull may only add to the danger.

The slaughter of caged civets in wild animal markets in Guangdong province began yesterday when China announced the first case of Severe Acute Respiratory Syndrome since a world epidemic was declared beaten in July.

Chinese health authorities said a gene sample from the new Sars patient — a 32-year-old television producer in Guangdong — resembled that of a coronavirus found in civets, a local delicacy.

The patient has fully recovered and will be discharged on Thursday, Xinhua news agency quoted health officials as saying.

In neighbouring Hong Kong, researchers said recent genetic studies detected changes in the Sars virus isolated from civets that suggest it may jump more easily to humans.

Health inspectors wearing surgical masks and carrying walkie-talkies patrolled the vast Xinyuan bird and livestock comprehensive market on the outskirts of Guangzhou, the Guangdong provincial capital, and local officials said 320 civet cats and other banned exotic animals had been seized.

The civets are drowned in chemical disinfectant and their carcasses hauled away in huge metal containers for incineration. Guangdong authorities have given a Saturday deadline for the slaughter of some 10,000 of the animals.

World Health Organisation officials have expressed concern that if the killing is not handled carefully it could create a risk by exposing humans to contaminated blood.

They also worry that by destroying the civets, medical researchers will lose vital evidence to help them understand how mutations in the Sars virus may be occurring.

Other experts warned the cull was not a full solution.

“The civet cat is only one of the origins of the virus,” said Hon Kam-lun, an assistant medical professor at the Chinese University of Hong Kong. “Some other animals also carry the virus. You can’t kill them all. The virus won’t be exterminated.”

Most Chinese urban residents shrugged off the danger, in stark contrast to the panic that gripped cities when Sars first appeared last year.

The calm reaction underlines the hard lessons learned by China’s Communist government last year, when it came under heavy international criticism for trying to cover up the epidemic, and a renewed public trust it now enjoys on Sars.

State media have issued details of the new case and the civet slaughter indicates a readiness to take prompt and draconian action to protect the population.