Two months after the world came to know about the large scale SARS (severe acute respiratory syndrome) infection which started from mainland China, information about its origin has come out. Also, a vaccine against the disease is just ready for trials. However, some experts say the claims about the vaccine are premature.

As this debate goes on about the status of the vaccine, what the world now knows with some certainty, is that the SARS virus may have originated in animals like the Himalayan or masked palm civets (a species of cat), raccoon dogs and badgers. Many Chinese consider the meat of these animals delicacies and consume them in large quantities. Blood tests of people who bought these food items in a market in Shenzen indicated that many of them were infected with the SARS virus. However, many of them did not develop the SARS disease.

According to Dr Klaus Stöhr, the Geneva-based scientific director of the World Health Organization (WHO) investigation said that a team of virologists headed by Dr Malik Peiris of Hong Kong University tested blood taken from 10 workers in the market and found antibodies to the SARS virus in 50 percent of the cases. The antibodies indicated that their immune systems were triggered by the presence of the virus.

Studies on workers in another market in the Guangdong province confirmed the presence of the virus in these animals. However, scientists cannot say with certainty, at this moment, whether the SARS virus has spread to other animals in the wild. If the virus has spread in the wild, then it would become very difficult to eradicate. For identification and destruction all infected wild animals might become a tough task.

SARS vaccine

Meanwhile, global attention has been turned on a group of doctors at Hong Kong University, Guangzhou Medical College and Fudan University's Shanghai Medical College who claim to have developed a vaccine, the first of its kind, against SARS. The doctors plan to start testing this experimental vaccine on animals in June. Results of the tests on animals would take at least six months. Tests on humans could be done only after animal test results were available.

However, some scientists at Hong University have said that the claims about the vaccine were premature. According to a report in The New York Times, scientists said the announcement about the vaccine was premature. What the groups have done, these scientists claimed, was that a strain of nostrils of mice was developed to test how the response system of the mice reacted to the SARS infection. The SARS virus was inactivated with the aim of inserting it in trial animals. "It is an inactivated virus but not yet a vaccine," a scientist said.

Doctors and experts at WHO would only confirm that " an attenuated (virulence decreased) virus" which was " non infectious " was ready.

Another good news was the decline in the number of reported cases in China. The average daily cases reported had more than halved to six and in May-end, there were in all 5,600 reported cases of SARS and 328 deaths.

N Suresh