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.

Uganda's Ebola virus caseload has risen to 12, up from 10, with two people who died early last month being considered probable cases, the World Health Organization said on Wednesday.

Health officials face challenge in containing the outbreak.