Forty-nine individuals have been identified who were in contact with a young Guinean woman who tested positive for the Ebola virus in Ivory Coast’s biggest city Abidjan, the UN health agency.

The 18-year-old had travelled to Abidjan by bus from Labe in northern Guinea, a journey of some 1,500 kilometres (950 miles) that traverses a densely-forested region where Ebola epidemics broke out earlier this year and 2013-16.

It is Ivory Coast’s first known case of the disease since 1994.

Ebola, which is transmitted through close contact with bodily fluids, causes severe fever and, in the worst cases, unstoppable bleeding.

Contact cases were identified from among fellow bus passengers as well as “among families at the starting point in Labe,” WHO specialist Georges Ki-Zerbo told an online press conference of the World Health Organization’s Africa branch.

A senior health official in Labe, Elhadj Mamadou Houdy Bah, on Wednesday, had said 58 contact cases had been identified there, and none had any sign of the disease.

An Ivorian doctor told the WHO press conference that 70 people were aboard the bus, of which 33 arrived in Abidjan, while the others are scattered across Ivory Coast.

The bus made stops in the western towns of Duekoue and Guezabo and in the administrative capital Yamoussoukro, he said.

“Through networking, we were able to home in on the communities” where the fellow passengers live, Health Minister Pierre Demba added.

“We are stressing the need for vigilance” by all health structures to spot any further cases, he said.

Three suspected cases have tested negative, according to Ivorian health authorities.

Demba travelled Wednesday to the Ivorian-Guinean border to raise awareness of the need for vigilance.

Matshidiso Moeti, the director of WHO-Africa, praised the two countries’ “remarkable solidarity” over the Ebola situation and the swiftness of the Ivorian response.

‘Doubts’ over diagnosis

Guinea, with aid from the WHO, sent 5,000 doses of the Ebola vaccine to Ivory Coast two days after the young woman’s infection emerged.

Vaccinations began in the country on Monday.

However, Guinean authorities on Thursday asked for a review of the initial diagnosis of the Guinean woman.

“The improvement in symptoms… in 48 hours raises questions, given the typical course of the disease,” Guinean Health Minister Remy Lamah wrote in a letter to the WHO.

The minister also said that a Guinean medical team sent to Abidjan could not gain access to the patient.

Labe, where the young woman is from, recorded no cases of Ebola during the previous outbreaks in Guinea, Lamah wrote.

He requested a “reconfirmation” of her infection by the Pasteur Institute in the Senegalese capital Dakar, which is a reference lab for West Africa, “and if possible by another accredited laboratory.”

The 2013-16 Ebola epidemics left 11,300 people dead in Guinea, Liberia and Sierra Leone, including 2,300 people in Guinea.

A four-month outbreak in Guinea claimed 12 lives in Guinea this year before being declared over on June 19.