Sars was 'lying in wait'
2003-09-24 19:23
Beijing - Recent studies in China indicate the pneumonia-like Sars virus might have existed in humans for some time, as scientists testing blood samples collected prior to the recent outbreaks found evidence of the virus, state media said on Wednesday.
The first known outbreak of Severe Acute Respiratory Syndrome occurred in southern China's Guangdong province in November. Another major outbreak was found in the capital Beijing the following spring, while other provinces and cities were also affected this year.
In one study, blood samples collected in 2001 and 2002 from 1 621 healthy youngsters from 17 provinces in China were analysed and 16 of the samples tested positive for Sars even though the samples were collected before the outbreaks occurred, the China Youth Daily said.
The study was conducted by the Beijing Military Zone Airforce Logistics Sanitation Unit.
No symptoms
In another study, the Beijing Capital Pediatrics Research Institute tested 92 blood samples collected from children during the outbreak and found that more than 40 percent of them tested positive for the Sars antibodies even though the children did not have any symptoms of Sars, the report said.
The research institute also tested blood samples from 77 child patients who were hospitalised in 2001 and found that 41.56 percent of them had the Sars antibody, the report said.
It tested another batch of 80 samples from 2001 and found that over 40 percent of them tested positive.
The blood came from children who did not have any symptoms.
Hiding in human bodies
The research seems to show that Sars can cause hidden, symptom-less infections and that it may have been "hiding" in human bodies for some time, the report cited researchers as saying.
Meanwhile, Beijing University's Number One Hospital conducted a study of blood samples collected from health workers who treated Sars patients and from other healthy adults and found that both groups did not have any Sars antibodies, the report said.
The hospital also tested Sars patients, and found that these people developed antibodies long after getting the disease, unlike the children tested by the paediatrics research institute.
The research seems to indicate children, for an unknown reason, develop the antibodies for Sars earlier on, whereas adults have not, which could explain why few children were infected during the outbreaks in China and around the world.
Further research is required before definite conclusions can be drawn, researchers said.
Sars infected more than 8 000 people and left more than 900 dead in 32 countries, with 349 of the fatalities and 5 327 of the infections recorded in 24 of China's 31 provinces, municipalities or autonomous regions.
Officials fear Sars is seasonal and could re-emerge this winter.