The disturbing feature of the current Ebola outbreak in West Africa isn't just that it's the largest and deadliest: it's also that so many health workers have lost their lives while caring for the sick.
The death toll right now is at least 60, according to the World Health Organization. To put that into context, in the second biggest outbreak in history—which took place in 1976 in Zaire—only 11 medical personnel died. And that was the first recorded outbreak in history, when measures to prevent transmission of the virus weren't well established.
Why are so many medical staff getting sick now?
First, we need to look at the total numbers affected. In 1976, the death toll was 280 and there were 318 reported cases. In this 2014 outbreak, there have already been 729 deaths and the number of reported cases has reached 1,323. As a point of comparison, that means this outbreak is four times larger than the 1976 flair up.
It's also more geographically dispersed. Previous outbreaks typically occurred in one remote area. Today, Ebola has reached rural and urban areas in Guinea, Liberia, Sierra Leone, and Nigeria. So the numbers of people affected are unprecedented, and therefore the proportion of health-care workers impacted is sadly going to be larger.
But don't we know how to protect health workers?
We do. Since the disease is transmitted through direct exposure to bodily fluids—from vomit to blood and sweat—health-care workers are advised to wear face masks, goggles, gowns and gloves while caring for patients.
The trouble is, health workers in the developing-country context—especially those working in some of the poorest countries on earth, where the disease emerged this time—don't always have access to this protective gear.
It's important to note that they are also the ones who have died in this outbreak. Of the 60 deaths so far, none involved foreign workers (though two Americans are currently battling the virus, and one is a doctor). Foreign aid agencies such as Doctors Without Borders—which apply stringent precautions for all their health personnel—have never lost members of their teams to Ebola. So the problem this time is as much about size of the outbreak as it is about resources.
"What happens in places that have less infrastructure, less developed hospital infection control is—unless you're very fastidious—you're at risk of transmitting the disease," said Dr. Scott Lillibridge, an infectious disease expert and assistant dean at the Texas A&M School of Public Health.
Still, even if health workers in these countries took full precautions and had access to every resource, at the beginning of an outbreak, medical personnel will inevitably get sick: at that point, doctors and nurses don't know what deadly bug lurks within their patients, particularly ones who present with a disease that sometimes masquerades as a common flu.
Exactly how are health professionals getting infected?
No one knows at this point. There was some speculation on the exact method of transmission at the CDC. But a WHO spokesperson told Vox "it's a bit of a mystery" right now. "There have obviously been lapses somewhere in how the doctors and nurses have protected themselves and we don't know if it's clinics that they're working in or elsewhere."