A surgeon from Sierra Leone has died of Ebola at the Nebraska Medical Center where he was being treated.

Dr. Martin Salia, is the second person to have died from the virus in the US.

He arrived from West Africa over the weekend. He was critically ill and considered sicker than other patients treated in the U.S. for the disease because he was suffering from advanced symptoms, including kidney and respiratory failure.

Salia was a permanent U.S. resident who spent part of his time at his Maryland home with his wife and son and also traveled to Sierra Leone to work as a surgeon. He said he knew it was a challenging job.

(SOUNDBITE)(English) DR. MARTIN SALIA SAYING:

"I knew it wasn't going to be rosy."

(SOUNDBITE)(English) DR. MARTIN SALIA SAYING:

"I took this job not because I wanted to but because I firmly believe that it was a calling and God wanted me to."

Dr Salia's family says he contracted the virus while working in a Freetown hospital.