Presumably, few Christian missionaries want others to discuss their sex lives, but with the discharge of Kent Brantly and Nancy Writebol from Emory University Hospital over the past few days, I've been thinking about just that. A life of studying infectious disease will do that to you.
I've already noted that Ebola can be spread by body fluids — blood, vomit, feces. Studies have also shown that, at least in theory, the virus could also be spread by infectious semen and vaginal fluids. In one paper, live Ebola virus was isolated from semen 40 days after the patient first became ill. Others found similar results using molecular methods: Semen was positive for molecular markers of Ebola as long as 91 days after symptoms appeared in one publication, while others found that semen could be positive for as long as 101 days and vaginal fluids for 33 days.
Theory is one thing, but is there any epidemiological evidence to suggest that Ebola has ever been spread this way?
An instance of possible transmission via sex has been reported, but with more reservations than Manhattan restaurants on New Year's Eve. The study followed up with individuals who had survived Ebola virus disease during the 1995 outbreak in Kikwit, Democratic Republic of Congo, and their household members. Samples of blood and other body fluids were taken to examine presence of Ebola virus and antibodies against the virus, which would indicate an infection had occurred, even if the patient showed no symptoms. A woman did test positive for Ebola antibodies in one test, but not in another test carried out almost 2 years later. Her partner was also positive for Ebola virus in his semen, and they noted that condoms were not always used during sex. Far from definitive proof, but between that anecdote and the positive fluid samples, the authors recommended condom use for at least 3 months after recovery from the disease.
With the present cases in the United States, it seems that physicians did pass this recommendation along to Brantly — no news on whether any similar recommendations were provided to Writebol, even though she could still be within the infectious phase as well.
The question of what to do with recovered Ebola patients highlights gaps in our Ebola knowledge. While more than 1,300 patients have now died in this outbreak, more than a thousand have seemingly recovered. The ability to study them would immensely increase our knowledge about Ebola virus disease. We already know that some people can have chronic symptoms that appear after the infection, like joint and bone pain or an eye condition that can cause blindness, but we don't know exactly why some people experience this and others don't.
The odds are very good that Brantly and Writebol are not a risk to their partners, even in the case of unprotected sex. Additional studies of Ebola survivors will let us say more definitively if this holds true.