GENEVA，Aug. 26 -- The World Health Organization (WHO) on Tuesday said in a statement that the Ebola outbreaks in West Africa is unprecedented in many ways, including the high proportion of doctors, nurses, and other health care workers who have been infected.

To date, more than 240 health care workers have developed the disease in Guinea, Liberia, Nigeria, and Sierra Leone, and more than 120 have died.

WHO said the deadly virus has taken the lives of prominent doctors in Sierra Leone and Liberia, depriving these countries not only of experienced and dedicated medical care but also of inspiring national heroes.

WHO noted shortages of personal protective equipment or its improper use, far too few medical staff for such a large outbreak, and the compassion that causes medical staff to work in isolation wards far beyond the number of hours recommended as safe contributed to the high proportion of infected medical staff.

WHO said capital cities as well as remote rural areas are affected, vastly increased opportunities for undiagnosed cases to have contact with hospital staff.

In many cases, medical staff are at risk because no protective equipment is available, not even gloves and face masks. Even in dedicated Ebola wards, personal protective equipment is often scarce or not being properly used.

In addition, personal protective equipment is hot and cumbersome, especially in a tropical climate, and this severely limits the time that doctors and nurses can work in an isolation ward. Some doctors work beyond their physical limits, trying to save lives in 12-hour shifts, every day of the week. Staff who are exhausted are more prone to make mistakes.

The loss of so many doctors and nurses has made it difficult for WHO to secure support from sufficient numbers of foreign medical staff.

According to WHO, the African Union has launched an urgent initiative to recruit more health care workers from among its members.