Doctors Without Borders, the group Craig Spencer volunteered for in Guinea, insists its rules are rigorous regarding protective gear and there is no need for stringent quarantines that might keep volunteers confined, charity officials said Friday.
Three health care workers, including Spencer, have contracted Ebola since March while on medical missions for Doctors Without Borders. Also known as Médecins Sans Frontières, or MSF, the charity is providing most of the medical care in a tri-country Ebola hot zone.
"Based on the information and science known today on the Ebola virus, isolating all MSF volunteers or other organizations' staff returning from West Africa would be an excessive measure to take," Sophie Delaunay, the organization's executive director said in a statement Friday.
The circumstances under which Spencer became infected have not been determined and a thorough investigation is underway, Delaunay said.
Dr. Victor Politi, chief executive of Nassau University Medical Center, said Spencer is a hero. "He was in a situation where he was dealing with overwhelming odds," Politi said.
Tim Shenk, a spokesman for the charity, said 21 African staff members who've volunteered during the crisis, which began this spring, have contracted Ebola in Guinea, Liberia and Sierra Leone. Another 13 volunteers have died. None were American, he said.
Ebola carries up to a 70 percent fatality rate in West Africa, where impoverished countries lack adequate medical facilities.
Shenk said his group's infection-control standards are among the most stringent worldwide.
"They are sprayed with a chlorine solution, which is a step in the doffing process," Shenk said, describing a .5 percent chlorine mixture sprayed on the gear.
A more diluted chlorine solution at an .05 percent strength is used as a direct skin-contact wash, Shenk said.
Spencer is said to have followed the organization's rules.
Dr. Bruce Farber, chief of infectious diseases for the North Shore-Long Island Jewish Health System, said it's difficult to speculate on how Spencer might have become infected.
"That's a tough question because it's not easy to put on and take off this equipment. It's the doffing that's really difficult, especially if you are heavily contaminated," Farber said.
Treating a patient in the early stages of Ebola may not produce much contamination on a health worker's gear, Farber said, but in late-stage Ebola, contamination may be unavoidable.
"This virus replicates astronomically and increases in high titers when a person is critically ill," Farber said, referring to the amount of virus in body fluids. "There might have been potential for some kind of inadvertent contamination. That can happen if you adjust your glasses or rub your nose, something like that."
Dr. Barry Rosenthal, chairman of emergency medicine at Winthrop-University Hospital in Mineola, said it's difficult to treat patients while in personal protective equipment. If there was a breach in protocol, it would be difficult to re-trace Spencer's steps.
"It's possible that he didn't come in contact with Ebola from a patient, but maybe from a surface or something he stepped on," Rosenthal said.
The virus has been known to stay viable two or more hours on surfaces, scientists have found.
"There's also a much greater risk [of infection] when there is a large volume of patients," Rosenthal said.
The charity's regulations on donning and doffing personal protective equipment were incorporated into tightened U.S. guidelines announced earlier this week by the Centers for Disease Control and Prevention.