Sierra Leone's lead doctor fighting the Ebola outbreak, the deadliest in history, has caught the disease, the government said today.

Sheik Umar Khan

Sheik Umar Khan, a 39-year-old virologist, has been transferred to a treatment ward run by medical charity Medecins Sans Frontieres. In a statement released by the president's office, the country's health minister Miatta Kargbo pledged he will "do anything and everything in my power to ensure [Khan] survives." 

The Ebola outbreak across West Africa has claimed 632 lives, with 206 deaths in Sierra Leone, according to the World Health Organization. With a 90 percent mortality rate and an incubation period of up to 21 days, the disease has been hard to track. 

Khan was known as a "national hero" by the country's health ministry for treating more than 100 Ebola victims.

"We are running behind Ebola," Anja Wolz, an emergency coordinator with the MSF running the treatment center in Kailahun, where Khan has been taken, told the WHO. "We came too late when villages already had dozens of cases and right now we don't know where all chains of transmission are taking place."

Reuters

These "chains of transmission" refer to the disease's viciously contagious nature. Because people who come into contact with infected bodily fluids of humans or animals are immediately in danger of infection, the WHO has been attempting to track down every possibly infected person without the three-week window.

Reuters

However, the country has limited resources, according to Sierra Leone Chief Medical Officer Dr. Brima Kargbo. "Our health workers are not well prepared," Kargbo said. "External assistance is very much appreciated." In fact, three nurses reportedly died of the disease, leading their colleagues at the government hospital in Kenema to go on strike Monday.

In June, Khan talked to Reuters about the risks of treating patients in his country.

"I am afraid for my life, I must say, because I cherish my life," he had then. "Health workers are prone to the disease because we are the first port of call for somebody who is sickened by the disease."