Although researchers have known since 1999 that traces of the Ebola virus could remain in the sperm for months two articles published in the New England Journal of Medicine today offer more details about the frightening possibility that survivors could rekindle infection outbreaks. A study focused on nearly 100 men in Sierra Leone who survived the dreaded viral disease, while the second clearly documents a case of sexual transmission of Ebola.
In Sierra Leone study, researchers found Ebola viral RNA in semen samples from nearly half of the 93 men, they tested. The probability of finding viral RNA decreased over time from onset of the disease has increased: All nine men were tested 2-3 months after they became sick showed signs of Ebola RNA in their sperm, but the researchers found that in 26 of the 40 men whose infections had started 4-6 months earlier and in 11 of 43 men whose infections had started 7-9 months earlier. The test result of Ebola patient 10 months after the onset of the disease was unknown.
The detection of viral RNA does not mean that these survivors are home to a virus that is able to establish an infection in a sexual partner. "We do not yet have sufficient information to assess the risk of transmission through sex, oral sex, or other sexual acts of men with viable virus in their semen," the authors of Sierra Leone and the World health organization (WHO) says. the scientists from the Centers for disease Control and Prevention (CDC) in Atlanta trying to isolate the virus from samples of semen, said Nathalie Broutet, an epidemiologist for infectious diseases in WHO in Geneva and one of the authors of the study.
in the second article, researchers from Liberia and the United States provides the best evidence yet of sexual transmission. a 44-year-old woman Montserrado County was diagnosed with Ebola, on March 20 and died a week later. the country has had no cases of Ebola in the previous 30 days and there was no obvious source of infection, but the patient reported having had unprotected vaginal sex with an Ebola survivor, March 7. The man had contracted Ebola in September 2014 and left the Ebola treatment unit after testing negative for the virus in early October. A human semen sample taken in March 2015, tested positive for Ebola, and genetic analysis of the woman's virus showed that it was separate from the most recent cluster in Liberia and the neighboring countries. Above all, his virus was all but identical to the isolated survivor: A single base pair differs between the two genomes. The "one gene signatures in the sample obtained from the seed of the victim and the woman died, I really think that provides conclusive evidence," says co-author Vincent Munster, a virologist at the US National Institute of allergy and infectious diseases in Bethesda, Maryland.
Broutet CDC said sexual transmission is suspected in about 20 cases in West Africa. WHO has changed its advice to survivors in May this year, after evidence showed that the virus could persist much longer in sperm than previously thought. The guidelines now recommend the survivors to abstain from sex or use a condom for 6 months or until their negative sperm tests. Given that there are thousands of male survivors who could spread the virus through sex, "the chances of sporadic cases ignition of small epidemics is very real," says Jonathan Ball, a virologist at University of Nottingham, UK.
The papers came amid news that Pauline Cafferkey, a British nurse who fell ill with Ebola in December 2014 and survived, was in critical condition at the Royal Free Hospital in London and ongoing processing "to Ebola" after apparently suffering a relapse. All this shows that the virus has the potential to surprise the scientists, said Munster. "An epidemic of this magnitude has never happened before with the Ebola virus, so I think we must realize that the data collected from previous epidemics might not be enough."
The survivors have already endured a painful and often lost relatives, Armand Sprecher of Doctors Without Borders in Brussels warns in an editorial accompanying the two papers. "If they are then treated as outcasts and threats, we add a terrible malice on top of their suffering," writes Sprecher. "They must be treated with all the compassion we can muster."
wHO today issued a progress report which said for the second consecutive week, no new cases of Ebola virus have been confirmed in all West African countries.
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