A second doctor on the frontlines of the deadly Ebola outbreak plaguing West Africa has been infected himself, according to government officials. Virologist Sheik Umar Khan, 39, has contracted the disease after being credited with treating over 100 patients in his native Sierra Leone.

According to the World Health Organization, over 632 deaths have been confirmed due to the outbreak, spanning three African states. Sierra Leone has been hit hard with Ebola; there have been 206 deaths so far and many more infected. Guinea and Liberia are also suffering tremendously from the disease's spread.

"I am afraid for my life, I must say, because I cherish my life," Khan said to Reuters in an interview in June. According to Reuters, Khan seemed to be in good health at the time of the interview.

"Health workers are prone to the disease because we are the first port of call for somebody who is sickened by disease," Khan said. "Even with the full protective clothing you put on, you are at risk."

A statement from the president's office released Tuesday said that Khan is in a treatment ward in Kailahun run by the medical charity Doctors Without Borders. Health Minister Miatta Kargbo said she would "do anything and everything in my power to ensure he survives."

Three nurses working in the same treatment camp as Khan died of infection Sunday.

There is no cure or vaccine for Ebola and the virus kills almost 90 percent of those infected. The first infections began in southeast Guinea in February and has since spread across the region. Fear, suspicion and burial traditions in local cultures all make it more difficult for health workers to prevent the spreading.

Earlier in July, a Ugandan doctor, Samuel Muhumuza Mutoro, died in Liberia after being infected from treating ill patients. Other instances are also being reported of nurses' strikes and health workers being infected.