Published: Oct 10, 2014 | Updated: Oct 14, 2014
PHILADELPHIA -- The mantra of Ebola experts is that the disease is transmitted through direct contact with patient body fluids that contain the virus. But which fluids? And are they all equally risky?
"The most commonly encountered bodily fluids are going to be the ones that are associated with the symptoms of the illness," according to Rob Fowler, MD, of the University of Toronto in Canada.
In other words, healthcare workers are most likely to encounter vomit and diarrhea, Fowler told MedPage Today during the IDWeek meeting here, where he presented an update on the Ebola epidemic raging in West Africa.
Blood runs a close third, he said, although -- contrary to popular belief -- extensive bleeding is not a common symptom of the disease, but it can emerge from the gastrointestinal tract in some cases.
And then there are a "host" of other fluids that contain varying amounts of virus and are less commonly met, both in casual contact and in the healthcare setting, he said.
"But all bodily fluids are a risk," he said.
Fowler, who has spent most of the past several months in West Africa on behalf of the World Health Organization, told MedPage Today that avoiding those risks on the front lines of the epidemic is a daunting challenge.
Indeed, the WHO reported this week that 401 healthcare workers have been infected and 232 have died in the 10-month outbreak -- in many cases, Fowler believes, because of a moment's inattention to personal protective equipment brought on by overwork.
In hospitals in the U.S., such a risk would be mitigated by the so-called buddy system, in which healthcare providers work in pairs, watching each other for a potential exposure and, if possible, averting it before it happens, commented Jeff Duchin, MD, of the University of Washington in Seattle and a spokesman for the Infectious Diseases Society of America (IDSA).
"If skin is exposed, it should be washed immediately and the healthcare worker monitored for 21 days," Duchin told MedPage Today. "Watching one another, making sure PPE (personal protective equipment) is in place, that there's no exposed surfaces, to rapidly correct any identified breaches of PPE before the opportunity for transmission occurs, is very important."
But in West Africa, where healthcare facilities are overwhelmed, implementing the buddy system is difficult, Fowler said. "It's hard to buddy with two doctors and 90 patients" needing care, he said.
The WHO agrees with Fowler that most body fluids can contain Ebola. But in a situation assessment issued Oct. 6, the agency says the most infectious are blood, feces, and vomit.
The virus has also been found in breast milk, urine, and semen. Indeed, in a convalescent male, the virus is known to persist in semen for at least 70 days and perhaps as long as 90, the agency reported.
The agency added that saliva and tears might also be risky, although studies implicating them were small and the "science is inconclusive." As well, the complete live virus has never been found in sweat.
It's also possible to transmit the virus indirectly by contact with body fluids on a surface, the agency report said, although the risk is low and can be reduced further by cleaning and disinfecting the surfaces.
Interestingly, a clinician from Atlanta's Emory University Hospital reported here that viral RNA was not found on surfaces in the biocontainment unit where two Ebola patients were treated this summer.
The virus is not airborne in the sense that the flu and cold viruses are, the agency noted, where transmission occurs after inhalation of an infectious dose of virus from a suspended cloud of small dried droplets.
That hasn't been seen with Ebola over several decades of observation, the WHO report said, and epidemiological data from the current outbreak are not consistent with airborne spread.
On the other hand, it is possible that -- over a short distance -- large wet drops from a heavily infected person with respiratory symptoms or who vomits violently, could transmit the virus, the report said.
Again, the agency said, there are no documented cases of such transmission.
For healthcare workers, perhaps the biggest risk occurs when they are taking off their personal protective equipment at the end of a shift, Fowler said. It's then that an inadvertent touch of the nose or eyes can transfer fluids from patients.
Indeed, news reports suggest that the Spanish nurse now in hospital with Ebola, 44-year-old María Teresa Romero Ramos, might have made just such a mistake.
Quoting various sources, the reports suggest that after caring for Spanish priest Manuel García Viejo, who later died of Ebola he contracted in West Africa, she touched her exposed face with her gloved hand.
Fowler noted that, if used properly and carefully, standard barrier precautions are enough to protect healthcare workers against Ebola.
But, he added, the stakes are higher than when they are used against a host of more common contact-transmitted viruses. "The consequences of getting it wrong are great," he said.
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