A person is being treated in isolation at Sweden's Uppsala University Hospital on suspicion of infection with Ebola, the regional authority said on Friday.
The patient was admitted to Enkoping hospital before being transferred to Uppsala. The emergency clinic at Enkoping was closed and staff who were in contact with the patient were being looked after.
"Test results will likely be ready some time tonight. This is still only a suspicion and other diseases are a clear possibility," the regional authority's statement said.
Symptoms such as fever and abdominal pain may appear up to three weeks after contact with the deadly virus, according to the U.S. Centers for Disease Control and Prevention.
The Democratic Republic of Congo has been experiencing an Ebola outbreak for almost six months, which has killed 356 of the 585 people infected.
The epidemic in a volatile part of Congo is now only surpassed by the 2013-2016 outbreak in West Africa, where more than 28,000 cases were confirmed.