In an update on March 8 the World Health Organization (WHO) shared new details about a second cluster of cases—three confirmed and two probable— in Uganda’ s Ebola Sudan outbreak, which have raised concerns about undetected transmission and have led to ramped up surveillance.

Africa’s top public health agency says that Uganda’s Ebola caseload increased to 14 in the last week with a new cluster emerging from a 4-year-old child who recently died of the infectious disease.

A new cluster of Ebola cases has emerged in Uganda, the Africa Centres for Disease Control and Prevention (Africa CDC) said on Thursday, adding that efforts were being made to intensify monitoring and contact-tracing measures.

Health officials face challenge in containing the outbreak.