SARS: WHO Website

The WHO has a dedicated Sars page where you can find ( here ) all the important updates.The latest release is more-or-less encouraging.

The agent that causes SARS has now been conclusively identified. The SARS virus is a new coronavirus unlike any other known human or animal virus in the Coronavirus family. Because the virus is new, much about its behaviour is poorly understood. Key questions, which are undergoing intense study, include stages in the course of infection when virus shedding may be highest, and the various concentrations of virus in different body fluids. Scientists are also working to determine the amount of time the virus can survive in the environment on both dry surfaces and in suspension, including in faecal matter.

The vast majority of countries reporting probable SARS cases are dealing with a small number of imported cases. Experience has shown that when these cases are promptly detected, isolated, and managed according to strict procedures of infection control, further spread to hospital staff and family members either does not occur at all or results in a very small number of secondary infections. These experiences confirm abundant early evidence that the SARS virus spreads, in the vast majority of cases, through exposure to respiratory droplets during close face-to-face contact.

However, information now emerging from outbreaks in Hong Kong and Canada is raising some important new questions about SARS. In Hong Kong, a large and sudden cluster of almost simultaneous cases (321) seen in residents of the Amoy Gardens housing estate has raised the possibility of transmission from an environmental source.

In addition, reports from Hong Kong health authorities indicate that patients in this cluster depart in some ways from the previously established clinical picture. The disease appears to be more severe both in Amoy residents and in related cases among hospital staff. Around 20% of Amoy-related cases require intensive care, compared with 10% seen in non-Amoy cases. Some deaths are now occurring in younger, previously healthy persons as well as in the elderly and persons with underlying disease. Around 66% of Amoy Gardens patients present with diarrhoea as a symptom, compared with 2% to 7% of cases in other outbreaks.

Speculation centres on whether these cases represent infection with high virus loads, as might occur following exposure to a concentrated environmental source, or whether the virus may have mutated into a more virulent form. Viruses in the Coronavirus family are known to mutate frequently.
Source: WHO
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This last part may be better understood after reading the following piece from the New Scientist:

A cluster of SARS patients in Hong Kong with unusual symptoms has prompted concern that the virus causing the disease is mutating. Doctors fear the changes are making the disease more severe. Scientists in Hong Kong are now urgently sequencing key genes from recently isolated coronaviruses to reveal any changes. New Scientist has learned that the changes in symptoms mirror those already seen when animal coronaviruses have mutated. Microbiologist Yuen Kwok-yung, at the University of Hong Kong, said on Wednesday that the 300 patients from a SARS hot spot, the Amoy Gardens apartment complex, were more seriously ill than patients who acquired the infection elsewhere.The Amoy Gardens patients are three times as likely to suffer early diarrhoea, twice as likely to need intensive care and less likely to respond to a cocktail of anti-viral drugs and steroids. Even medical staff who caught the infection from Amoy Gardens patients are more seriously ill, Yuen said.

The comparison of the symptoms is continuing, says John Tam, a microbiologist at the Chinese University of Hong Kong. "But at the same time we are studying the genetic sequences of the viruses involved in both outbreaks. The presence of a mutation leading to an altered tissue preference of the virus cannot be discounted at the moment," he told New Scientist.

The much higher rate of diarrhoea in Amoy Garden cases supports the idea of an altered tissue preference, meaning a viral strain that can attack the gut as well as the lungs. This switch mirrors effects seen in several animal coronaviruses. A bovine gut coronavirus, with some genetic sequences similar to the SARS virus, can also cause severe pneumonia in cattle. And in the 1980s, a pig gut coronavirus suddenly mutated into a respiratory infection in pigs.These switches involved mutations in the viral genes coding for the spike proteins, which form the protruding halo that gives coronaviruses their name. Luis Enjuanes and colleagues at Spain's National Centre for Biotechnology in Madrid have switched the pig virus from a mild respiratory infection to a virulent gut infection solely by changing the spike protein gene. Ominously, the gut form replicated much faster.
Source: New Scientist
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