A five-year-old boy has died of Ebola in Uganda, a health official said on Wednesday, in the first case of the disease crossing the border from the current outbreak in the Democratic Republic of Congo.

The boy died overnight, the official told Reuters, after entering Uganda from Congo with his family. His mother had returned to Congo to nurse her father, who died of the disease, the health minister said on Tuesday.

Uganda’s health ministry and the WHO sent a team to the western town of Kasese to trace likely cases and vaccinate those who might have come into contact with the family, the statement continued.

Uganda has been on high alert since the start of the Ebola outbreak in DRC in August 2018. More than 2,000 cases of the highly contagious virus have been recorded, including 1,357 deaths, in eastern DRC’s North Kivu and Ituri provinces.