Two Filipino nurses working at St James' Hospital in Dublin have undergone tests for severe acute respiratory syndrome (SARS).
The two recently returned to Ireland from a region affected by the mystery virus.
The hospital said the tests were taken as a precaution after the two nurses began showing "flu-like" symptoms.
Doctors at the hospital are awaiting the results of tests carried out on the two nurses.
SARS has killed scores of people worldwide, the majority in Hong Kong and China, where it is believed to have originated.
Experts believe the disease was spread by businessmen and holidaymakers who visited affected areas while travelling around Asia.