CARE's Helene Gayle on medical leave

Dr. Helene D. Gayle is on medical leave from her post as president and chief executive of  Atlanta-based CARE USA.

A spokesman for the humanitarian organization declined to release details, citing privacy concerns.

It is unclear when Gayle will return to the organization she's led more than five years. Until then, Steve Hollingworth, chief operating officer,  has been named acting president and chief executive officer. Johnathan Mitchell will assume the role of chief operating officer in a previously-planned move.

Hollingworth was previously the country director for CARE India, one of the organization's largest overseas offices.

The temporary changes come as CARE and other humanitarian organizations grapple with the drought and famine in the Horn of Africa, which experts are calling one of the worst disasters in decades. CARE is helping  people in Ethiopia, Somalia, and Kenya with food, water, nutrition and other emergency assistance.

CARE spokesman Brian Feagans  said operations are continuing as normal and that Gayle's leave will not affect that.