(Bloomberg) -- Disease trackers have yet to identify how a teenager from rural Guinea treated for Ebola in a hospital in Abidjan sparked Ivory Coast’s first outbreak of the deadly viral disease in 27 years.

The World Health Organization has sent expert teams to both West African nations to help authorities scale up measures to find and prevent additional cases, the agency’s regional office in Brazzaville said in a statement Thursday. As of Aug. 18, there was one confirmed and three suspected cases in Ivory Coast that later tested negative, WHO said. Six high-risk contacts have been quarantined and 131 contacts identified. No deaths have been reported.

Ebola adds to West Africa’s infectious disease threats after Guinea detected a case of deadly Marburg virus disease earlier this month and the region’s Covid-19 fatalities almost tripled in the week through Aug. 15.

“These new outbreaks are a clear reminder that other health emergencies are not taking a back seat just because we are busy battling a global pandemic,” Matshidiso Moeti, WHO’s regional director for Africa, said in the statement. “Fighting multiple outbreaks is a complex challenge.”

The 18-year-old patient traveled from the Labe region in Guinea, near the border with Senegal, to Abidjan, on public transport. She stopped multiple times during her five-day trip, including through Nzerekore, Guinea’s second-largest city, where an Ebola outbreak was declared over two months ago. 

The teen developed a fever after leaving her home in rural Guinea. Her symptoms worsened to include headache and bleeding from her gums by the time she arrived in Abidjan, a city of almost 5 million people, on Aug. 12, the WHO said in a report. 

Some 5,000 doses of Ebola vaccine are being administered to health care workers, first responders, contacts and others at high risk of infection, the WHO said. 

As of Wednesday, 49 people in contact with the Ebola patient have been identified in Guinea, and health authorities are preparing to vaccinate high-risk contacts there, the agency said.

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