Terrified patients fled from a hospital in western Uganda as soon as news broke that a mysterious illness that killed at least 14 people in the region was Ebola, one of the world's most virulent diseases.

Ignatius Besisira, an MP for Buyaga East County in the Kibaale district, said people had at first believed the unexplained deaths were related to witchcraft. "Immediately, when there was confirmation that it was Ebola … patients ran out of Kagadi hospital (where some of the victims had died)," he told the Guardian. "Even the medical officers are very, very frightened," he said.

Government officials and a World Health Organisation representative confirmed the Ebola outbreak at a news conference in Kampala on Saturday. "Laboratory investigations done at the Uganda Virus Research Institute ... have confirmed that the strange disease reported in Kibaale is indeed Ebola haemorrhagic fever," they said in a joint statement.

Health officials said at least 20 people had been infected and of those 14 had died.

There is no treatment or vaccine against Ebola, which is transmitted by close personal contact and, depending on the strain, can kill up to 90% of those who contract the virus.

It has a devastating history in Uganda, where in 2000, at least 425 people were infected, of whom more than half died. Ebola was previously reported in the country in May last year, when it killed a 12-year-old girl.

During an outbreak in 2007, which claimed at least 37 lives, President Yoweri Museveni advised people not to shake hands and public gatherings were also discouraged.

One of those who succumbed to the outbreak in Kibaale was a clinical officer, Besisira said. The other fatalities came from a single household in Nyamarunda subdistrict, he added.

Joaquim Saweka, WHO's representative in Uganda, said the suspected infections emerged in the region in early July but the confirmation came only on Friday.