Saturday, 4 April 2015

Ebola - the lesser transmission risks are still risks...

The United Nations (UN) Foundation blog has used some pretty strong language in their latest post of the 5 Things to Know on Ebola This Week.

Number 2 on their list stated (by highlighting)...
First detected case of Ebola transmitted through sexual intercourse
Earlier research suggested that three months of abstinence or condom use among male survivors would suffice to prevent the transmission of Ebola through intercourse. But an Ebola patient in Liberia who died last week had just one known risk factor: her boyfriend was an Ebola survivor, treated last September. This is the first case detected of the Ebola virus being transmitted through sexual intercourse, which has necessitated updated recommendations. Read the full story here: http://unfoundationblog.org/ebola/5-things-to-know-on-ebola-this-week-10/#sthash.2HkUbbYT.dpuf
While there is reported to be ongoing testing (and presumably virus genotyping), I've yet to hear publicly the outcome of such testing. 

Perhaps the results are known behind closed doors and perhaps that testing has firmly pointed to a sexual transmission route. The UN post above certainly seems very sure and it also seems that this event has triggered an update to recommendations. There is solid literature about the presence of infectious Ebola virus in seminal fluids so the possibility shouldn't be far beyond belief.[4]

Another possible, albeit also unproven, transmission route is urine. This fluid seems to me to be a far more likely source of trouble. One cannot abstain from urination. So why worry about urine as a risk for transmission of Ebola virus? An EVD case study last year showed very nicely that infectious Ebola virus could be cultured from urine for about 12 days longer than it could be from blood.[1] Viral RNA has also been found in urine for four weeks.[1,2] 

Perhaps urine should be a more noteworthy concern for its potential to remain infectious after blood test become negative. This concern might be greater wherever toilet and hand-washing facilities and sewers, are minimal or poorly maintained.

Urine and seminal fluids are not considered to be major transmission routes for Ebola virus. But let's not forget that it was probably an unlikely transmission event, and route - a single jump from an animal to a human - that triggered >25,000 EVD cases in this epidemic. Even a rare risk must be given serious consideration when such a large public health impact can realistically result.

References...

  1. Kreuels B, Wichmann D, Emmerich P et al. A Case of Severe Ebola Virus Infection Complicated by Gram-Negative Septicemia. N Engl J Med. 2014 Oct 22. 371:2394-2401
  2. Lyon GM, Mehta AK, Varkey JB et al. Clinical Care of Two Patients with Ebola Virus Disease in the United States.  N Engl J Med. 2014 Nov 12. 371:2401-2409
  3. Ebola Virus Disease (EVD). Key questions and answers concerning water, sanitation and hygiene. World Health Organization. http://apps.who.int/iris/bitstream/10665/137181/1/WHO_EVD_WSH_14_eng.pdf?ua=1
  4. Mackay IM, Arden KE. Ebola virus in the semen of convalescent men. Lancet Infect Dis. 2015 Feb;15(2):149-50.