The Ebola virus is endemic in certain areas of Africa, where viral outbreaks still exist to this day. For example, there were at least three Ebola outbreaks in Africa during 2021. Scientists and health leaders are currently working to combat the virus and its spread through vaccinations and monoclonal antibody treatments.

However, researchers have noted that some people who get Ebola and survive the outbreak experience a persistent and sustained infection. Despite this infection, researchers have been largely unable to determine where the virus was “hiding” and what could cause it to re-emerge, especially in people who had already been treated. 

According to Medical Xpress, a research team from the U.S. Army Medical Research Institute of Infectious Diseases recently sought out to answer this question using a nonhuman primate model. To read the full study findings, take a look at the recent article published in Science Translational Medicine. 

The Research

To begin, researchers used nonhuman primate models to evaluate the effects of Ebola – and to determine where the virus was reemerging from. After infecting the animals with Ebola virus, the research team then analyzed the response. The animals were then given monoclonal antibody treatments, which helped to clear the virus out from various bodily organs.

However, researchers determined that the virus was persisting within the brain’s ventricular system – or the area of the brain where cerebrospinal fluid is produced and held. This fluid is used to maintain the health of the central nervous system (CNS). Approximately 20% of animal models that survived following therapy, still maintained an Ebola infection within this system. Eventually, two of the subjects who had initially recovered from the virus later died following viral re-emergence. 

Additionally, research has shown that the virus may also “hide” within the vitreous humor in the eyes or within seminiferous tubules in the testes. Regardless, this research highlights the need to continually monitor and follow-up with those who previously had Ebola to ensure that the virus does not re-emerge and later spread. 

About Ebola

Also known as Ebola Virus Disease (EVD), Ebola is a rare and severe viral hemorrhagic fever. This viral infection can impact both humans and primates and is spread through contact with an infected party. In particular, Ebola is spread through blood, tissue, sexual contact, or bodily fluids. Without treatment, Ebola can be – and often is – deadly. The World Health Organization (WHO) notes that the average fatality rate is around 50%. Symptoms usually manifest within 2-21 days following infection, though the most common onset is between 8-10 days. These usually begin with “dry” symptoms, which later progress to “wet” symptoms. Potential symptoms include:

• Fever
• Fatigue and general malaise/bodily weakness
• Muscle and joint pain
• Headache
• Throat soreness 
• Diarrhea
• Nausea and vomiting
• Stomach pain
• Red eyes
• Skin rashes
• Unexplained bruising, bleeding, and hemorrhaging 

Learn more about Ebola.