Ebola virus can infect reproductive organs of humans, according to a study conducted on macaques.
Prior studies of survivors of the 2014-2016 Ebola outbreak in West Africa have revealed sexual transmission of Ebola virus, and that viral RNA (Ebola virus genetic material) can persist in semen following recovery.
While little is known about viral persistence in female reproductive tissues, pregnant women with Ebola virus disease have a maternal death rate of more than 80 % and a foetal death rate of nearly 100 %.
Researchers from The National Institute of Allergy and Infectious Diseases in the US infected four female and eight male macaques with the Makona variant of Ebola virus, the variant responsible for the recent West Africa outbreak. All the macaques succumbed to Ebola disease and were euthanized six to nine days after infection.
The scientists then took reproductive tissue samples from each macaque and analysed the samples for signs of Ebola virus infection, organ and tissue damage, and immune responses. They found widespread Ebola virus infection of reproductive organs with minimal tissue immune response or signs of disease.
Based on the findings, published in The American Journal of Pathology, the researchers hypothesised that Ebola virus can persist in these tissues in human survivors, and that the virus may reach seminal fluid in men by infecting immune cells called tissue macrophages.
However, it is unclear if the detection of Ebola virus RNA in semen documented in human studies means that infectious virus is present.
According to the scientists, additional research is needed to learn how Ebola virus persists in these sites, to determine if drugs and vaccines can cure or prevent such infections. They also need to understand the mechanisms of sexual transmission, including why it appears to occur only rarely in humans.