Health officials across Africa are racing to determine how Nigeria’s first Ebola patient ⁠in more than a decade ⁠became infected, amid fears ​the outbreak could spread further after reaching a fourth African country.

The Swiss foreign ministry said on Friday the patient in Nigeria, the Ugandan-born wife of a Swiss diplomat based in Abuja, had not travelled to the Democratic Republic of ⁠Congo, where the outbreak was first detected in mid-May before spreading to Uganda , Kenya and now Nigeria. The woman was believed to have contracted Ebola while travelling with her husband in Uganda, the ministry added.

The new information contradicts accounts from Uganda, which previously said the woman had travelled to eastern DR Congo, and will raise concerns about the ability of authorities to contain the outbreak, which is already the most geographically widespread in history.

The Ugandan government reported Ebola cases in May and June before WHO declared it Ebola-free in August.…