Since the outbreak of Ebola began in South Africa barely two years now, scientists have found that the virus strain can remain in the semen even after the person is declared free of transmission. But a recent study published in Nature suggested that though the prevalence of Ebola sexually-transmitted disease is relatively low in West Africa, it is expected the figures would rise in the coming months following the virus’ incubation period.
Two clinical trials were performed to determine the existence of Ebola strain on the person’s RNA between two to nine months after the person is first diagnosed of having Ebola symptoms. Half of the 93 recruited men tested positive, which was unsurprising since the virus strain is known to linger in the semen for months. The longevity of the strain found in the samples went as far as seven to nine months.
The other clinical trial, which involved a Liberian woman, confirmed she is the first known case of sexual transmission containing Ebola. The woman reportedly did not show any symptoms of Ebola, nor did not have any contact with an infected person, except at the time when she had unprotected case with a man whose semen tested positive with the virus.
Co-author Gustavo Palacios, whose team is coordinating with the Liberian government, said the woman’s case is moved from being “probable” to “confirmed”. However, laboratory tests showed that only one gene mutation contained the virus versus the 796 sequences tested.
Researchers from Sierra Leone, in conjunction with the World Health Organization and the U.S. Centers for Disease Control and Prevention, were unable to sample live virus. Instead, they tested for specific genetic sequences in the men’s semen that have Ebola strains.
Michael Wiley, a researcher at the Center for Genome Sciences at the US Army Medical Research Institute of Infectious Diseases, said the samples showed dead virus and not all of the RNA detected with Ebola were confirmed infectious.
WHO spokeswoman Margaret Harris said they are working to see whether they can separate the live virus from the semen. Follow-up tests will be conducted to identify if the semen containing dead Ebola virus poses significant health risks.
As of the study’s publication, evidence showed there has been no confirmed case of Ebola transmission so far and the possibility is very low. The only known related instance was the case of sexual transmission through Marburg virus, which also came from the same family as Ebola.
In response, the WHO revised its guidelines for Ebola recovery period from three months to five months. Those who tested positive and recovered after three months are required to be re-tested every month until two consecutive tests indicate negative results.