The World Health Organization has declared the Ebola outbreak in the Democratic Republic of Congo a Public Health Emergency of International Concern, as the virus crosses borders and hits urban centers.

WHO chief Tedros Adhanom Ghebreyesus said he was “deeply concerned about the scale and speed of the epidemic.” Cases have now been confirmed in Uganda’s capital, Kampala, and a U.S. citizen was flown to Germany for treatment.

So far, the outbreak has killed 131 people and infected 513, according to DRC health officials. Tedros noted that cases have appeared in urban areas like Goma and Kampala, raising the risk of wider spread.

The outbreak involves the Bundibugyo strain of Ebola, for which no vaccines or treatments exist. Tedros also cited rising insecurity in Ituri province, where over 100,000 people have been displaced, complicating containment efforts.

Health workers have died, signaling transmission within healthcare settings. Tedros has convened an emergency committee to advise on temporary measures.