Indonesian health authorities are investigating the deaths of 22 people over a two-month period admitted to the same hospital in the capital, Jakarta.
All of the victims were over 40 years old, lived near the hospital, and died from an unidentified illness accompanied by high fever. Most recent death was reported on November 27.
A senior Health Ministry official said health authorities have eliminated known communicable diseases, such as SARS and bird flu, but that the cause of the deaths is still unknown.
A source close to the ministry said samples from the patients were sent to the ministry's laboratory and to the U.S. Naval Medical Research Unit in Jakarta.
The source said health authorities checked other hospitals in Jakarta but found no other cases.
Some information for this report was provided by AFP and AP.