Health officials have identified a Hong Kong hotel as the likely starting place of a strain of pneumonia that has been blamed for up to 14 deaths worldwide.
A doctor from China's Guangdong province had stayed at the Metropole Hotel in Kowloon district, where, it is understood, his coughing and sneezing spread the Severe Acute Respiratory Syndrome (SARS) bug. He has since died.
As the source was being identified it was confirmed that the two suspected cases of SARS being treated at separate Dublin hospitals were no longer considered to be infected. The patients were being treated at St James's and Beaumont Hospitals. The Department of Health said these patients had been "de-notified to the World Health Organisation as suspect cases".
However, an expert group set up by the Minister for Health, Mr Martin, will continue to monitor the situation.
The virus, which has infected hundreds across the world, mainly in Hong Kong, Vietnam, Singapore and China, has no known cause and does not respond to standard drugs. Its symptoms are flu-like, including high fever, coughing and shortness of breath. They have only been found in people who visited affected areas or had contact with others who became infected.
Two probable cases of SARS have been reported in the UK - in Manchester and London - and a suspected case is being investigated in Wales. All patients are stable.
When news broke that the bug was connected to a Hong Kong hotel, several guests checked out.
The World Health Organisation, which last weekend labelled SARS a global health threat, said the link between the hotel and cases of SARS "could be useful to try to trace the transmission of the bug and find people who could have been exposed to it".
However, WHO spokesman Mr Ian Simpson said the link did not help identify a cause or a cure for the illness.
Tests in Germany and Hong Kong found particles of a virus from the Paramyxoviridae family was present in infected patients but Mr Simpson said it was not possible to tell if this was the cause of the illness or simply present in the patients.
Hong Kong's director of health, Ms Margaret Chan, said the illness had been traced to a sickly doctor from southern China who stayed at the Metropole Hotel in February.