The deadly Sars virus has been found in tears, it has been announced.
Scientists believe Sars is here to stay
Doctors in Singapore swabbed the tear ducts of 36 patients with suspected Sars in April 2003. Eight of these were later diagnosed with probable Sars.
The doctors have now revealed that they found signs of Sars in the tears of three of these patients.
Writing in the British Journal of Ophthalmology, they said the findings suggest the virus could be transmitted through tears.
The highly infectious respiratory illness Severe Acute
Respiratory Syndrome, or Sars, first emerged in China's southern province of Guangdong in late 2002.
It affected more than 8,000 people throughout 2003 in dozens of countries worldwide and claimed the lives of 774.
A much smaller outbreak occurred earlier this year. Many scientists believe the virus is here to stay.
There is still no vaccine to protect against Sars and there is no specific cure, although existing drugs appear to work for some people.
Scientists are trying to develop a test which would enable doctors to diagnose the virus earlier.
Dr Seng Chee Loon and colleagues at Singapore's National University say analysing tear samples could be one way of spotting the virus.
The three patients who had signs of Sars in their tear ducts were all believed to be in the early stages of infection.
They had all been tested within nine days of their symptoms starting.
The remaining patients, who had no signs of the virus in their tears but were later diagnosed with probable Sars, were tested at least 11 days after the start of their symptoms.
The doctors suggested that Sars may only be present in the tear ducts in the early stages of the virus.
Signs of other viruses, such as herpes, hepatitis and measles, have also been detected in tears.
The doctors are now planning to carry out further tests to see if analysing tears could be a way of spotting Sars.
"Even as the epidemic has died down, we are warned of future outbreaks.
"This may be a simple tool in identifying probably cases in future and prospective trials are being designed for this purpose," they wrote.