SARS unravelled

Published: Thursday 15 May 2003

SARS unravelled

Between March 25 and 27, 2003, two different groups of researchers in the cdc and Hong Kong University announced that a previously unrecognised coronavirus could have caused the sars epidemic. This family of viruses is the second leading cause of colds in children and premature infants but has never been perceived to be a serious health threat. Other labs in Hong Kong, Germany and Singapore proposed that another virus from the family of polymyxovirus could be a helper or a cause of co-infection in sars. But on April 15, the who confirmed that monkeys experimentally infected with a new coronavirus developed an illness similar to sars.

Close contact with infected persons raises the risk of contracting sars. Transmission usually takes place through direct contact with respiratory secretions and body fluids of patients. But another recent discovery that it can survive in human faeces implies that unhygienic conditions even in homes -- like moist toilets and sinks -- could enable the virus to survive for long periods of time. The people who checked into the Metropole hotel in Hong Kong show that the virus can endure in the area for several days and drift through airspaces into other rooms. In e-block of Amoy Gardens apartments in Hongkong, where 213 people got infected, it is believed to have spread through leaking sewage pipes and drains. "If the sars virus can infect from faeces and is capable of spreading via airborne sources, then we have a persistent killer on our hands," says Kiwana Thapurkakorn, influenza virologist at the Royal University of Bangkok. Cockroaches too have been alleged to carry the virus. Another strange mode of spread of sars is that some individuals spread the virus more prolifically than others. Doctors are still not sure if such patients carry an especially infectious form of the virus or whether some other factor, such as behaviour, was the cause.

What is perplexing is that who confirmed on April 19 that fatality rates have risen to 5.1 per cent of the infected population from 4 per cent at the beginning. Does this mean that the virus is becoming more virulent? Or does it simply mean that treatment is inadequate?

Antivirals like ribavirin supplemented with steroids have been suggested as treatment for full- blown sars.

Testing time
The who and cdc have a clinical diagnostic protocol for those affected by sars. They have laid down clear-cut guidelines in order to prevent suspected patients from coming into contact with infected people.

A team of scientists in the department of microbiology, University of Hong Kong, was the first to succeed in culturing the viral agent that causes sars. Using a special cell line, the Hong Kong scientists isolated the virus from the lung tissue of a patient who developed pneumonia following contact with a professor from Guangdong. Both persons have ince died. The scientists have devised a basic test that relies on neutralising antibodies. This "hand-made" technique will now be developed into a more sophisticated diagnostic test.

India's Mumbai-based srl Ranbaxy Limited is checking for the presence of coronavirus with its influenza test panels. These can be used to identify Influenza a virus, Influenza b virus, parainfluenza virus, respiratory synctial virus (rsv) and enterovirus. According to the company, if the virus does not turn out to be any of these, the disease can be assumed to be sars. "This is a diagnosis by exclusion," says Shishir Malwankar of Ranbaxy.

On April 16, the Institute of Medical Research in Malaysia and Germany's Hamburg-based company Artus announced that they had developed the first and only commercially available diagnostic kit. Since April 12, Singapore has used a high-tech thermal-imaging thermometer at Changi airport. The device automatically checks the temperature of air travellers as they step off the plane. These sensors alert health authorities to quarantine and isolate an infected person.

But sars is slippery. Singapore's ring-fence approach -- cordoning off the infected-seems to have suffered a setback when another hospital in the city was declared to have a patient of sars. Hong Kong on the other hand has had a significant rise because it believed in voluntary measures (self-reporting) rather than the military-style quarantining in Singapore. Germany, too, was able to isolate the single victim that reached Frankfurt airport and is reportedly keeping a keen watch.

In India, the first confirmed case in Goa was found to be a passive carrier who had crossed the "window" period. "As per who norms, the patient was released but asked to take rest and remain indoors," said Suresh Amonkar, Goa's health minister. Till Down To Earth went to press, the Pune case was the only active and confirmed sars case. A neighbourhood in Mumbai has been reportedly cordoned off by the hapless state government.

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