A mystery illness that causes people to vomit blood has killed 15 people and hospitalized more than 50 others in Tanzania.

The illness detected in the southern Mbeya region of the country has killed mostly male patients within hours of them developing symptoms, The Sun reported.

Tanzania borders the Democratic Republic of the Congo (DRC), where Ebola recently killed a woman three months after it was announced that the “last ebola patient” in the country had recovered in Equateur. Expert medical teams have been deployed to the area to try to uncover the cause of the outbreak.

Felista Kisandu, the local chief medical officer, confirmed that a team of experts have been dispatched to assess the patients and investigate the cause of their illness.

“This problem has not been widespread,” Kisandu said. “It has happened in just a single administrative ward of Ifumbo where people vomit blood and die when they get to the hospital late.”

She said the cause of their illness has not yet been identified but that the Tanzanian Health Ministry “has ruled out an outbreak,” according to the outlet.

“Initial clinical examinations revealed the patients, mostly men, suffered from stomach ulcers and liver disease,” Kisandu said. “We have advised them to avoid drinking illicit brew, smoking cigarettes and other hard drinks.”

Authorities were testing water samples and patients’ blood for traces of mercury contamination.

Meanwhile, Tanzania’s Health Minister Dorothy Gwajika reportedly ordered Kisandu’s suspension over her remarks