Nigeria confirmed its first Ebola case in more than a decade on Tuesday. The patient is a Ugandan-born woman married to a diplomat based in Abuja. She had traveled to Uganda in September and returned to Nigeria earlier this month, authorities said.

The woman is receiving treatment, and 44 people who had close contact with her have been quarantined, Dr. Wessam Mankoula, head of emergency preparedness and response at the Africa Centres for Disease Control and Prevention, said Thursday. Investigators are still trying to determine how she was exposed.

Mankoula said officials were examining whether there was “some sort of interaction between the two cases at the airport.” Nigeria’s patient may have been at Entebbe on the same day as the first Kenyan patient, who traveled from the Democratic Republic of Congo through Uganda to Kenya and later died in Nairobi.

Kenya’s health ministry said this week that the country had recorded nine cases. The first was reported in early October; eight more have since been identified, mostly among people with close connections to the initial patient, according to the account of the outbreak. Kenyan Red Cross personnel conducted a simulation in Nairobi on Oct. 22 to prepare for handling the remains of an Ebola victim.

The outbreak began in eastern Congo in May and has spread to several African countries. Congo has reported at least 9,700 infections and 4,600 deaths. Uganda, which initially recorded about 20 cases, was declared Ebola-free in August. Nigeria is the fourth African country to report a case in the current outbreak and the first in West Africa, far from the outbreak’s epicenter.

Ebola spreads through direct contact with an infected person’s bodily fluids or contaminated objects. People generally are not considered infectious until symptoms begin, underscoring why tracing travel and close contacts is central to the response.