The head of the World Health Organization expressed deep concern Tuesday over the scale and speed of an Ebola outbreak in the Democratic Republic of Congo, as health officials reported a sharp increase in suspected cases and deaths.

According to the Congolese Ministry of Health, at least 131 people are believed to have died from the outbreak, with 531 suspected infections reported. The numbers represent a significant rise since the outbreak was first documented over the weekend.

Health experts warn that the actual number of cases may be much higher than currently reported, raising concerns about the virus's potential spread across the central African region. The rapid escalation has prompted heightened monitoring from international health authorities.

Separately, the Centers for Disease Control and Prevention confirmed that an American citizen tested positive for Ebola while in Africa. However, CDC officials emphasized that the risk to the United States remains low.

The current outbreak marks another episode in the region's ongoing struggle with Ebola, a viral hemorrhagic fever that has caused multiple epidemics in West and Central Africa over the past decade. The WHO's expression of concern reflects the international community's vigilance in preventing the virus from spreading beyond the affected areas.