WHO team travels to Beijing to help investigate source of SARS

The United Nations World Health Organization (WHO) today is sending the first members of an international team to help investigate the source of cases of the Severe Acute Respiratory Syndrome (SARS) recently reported in Beijing and the eastern province of Anhui, which have now doubled to eight, following a request of China’s Health Ministry.

The team, which is expected to begin work Wednesday, will include experts in epidemiology, virology, infection control, and laboratory biosafety, WHO said in a news release.

Results of investigations so far point to laboratory research at the National Institute of Virology in Beijing as the likely source of the outbreak. The institute has been engaged in research with the SARS coronavirus, including the development of a vaccine.

Two of the recently reported cases were conducting research at the laboratory: a 26-year-old female postgraduate student from Anhui Province, and a 31-year-old man. The dates of symptom onset in the two cases are widely separated (23 days), suggesting that more than one opportunity for exposure may have occurred in the laboratory from mid-March through early April.

Authorities have closed the virology institute and placed its more than 200 employees under medical observation. Numerous environmental samples from the laboratory have been taken to help assess possible sources of contamination, and these samples will be shared with WHO.

WHO said it was concerned about additional opportunities for exposure that may have already occurred. Some patients were treated or assessed in several different hospitals before a suspicion of SARS led to the introduction of adequate precautionary measures, including isolation of patients and strict procedures for infection control. One patient twice travelled a long distance by train within China while symptomatic.

Since 22 April, China has reported that eight persons have been clinically diagnosed as SARS cases or are under investigation for possible SARS infection. Six of these are in Beijing and two, including the single fatality, are in Anhui. As of today, close to 1,000 contacts of these cases are under medical observation, including 640 in Beijing and 353 in Anhui.

The most recent cases, announced yesterday, are four close contacts of a 20-year-old nurse who treated the Anhui student at a Beijing hospital. The cases - all in Beijing - are currently under investigation.

In addition, health authorities have reported that two doctors who treated the postgraduate student during her hospitalization in Hefai, Anhui, have developed fever. A person in close contact with one of the doctors has also developed fever.

To date, all diagnosed cases and cases under investigation have been linked to chains of transmission involving close personal contact with an identified case. There is no evidence of wider transmission in the community.

According to WHO guidelines for the global surveillance of SARS, classification as a confirmed case at the start of an outbreak requires independent verification of results by an external international reference laboratory. Such procedures are considered necessary in view of the implications that confirmed SARS cases can have for international public health.