Composite scanning laser ophthalmoscope retinal images showing type 6 Ebola peripapillary or peripheral lesions, observed following the anatomic distribution of the ganglion cell axon (retinal nerve fiber layer), in a case–control study of ocular signs in Ebola virus disease survivors, Sierra Leone, 2016. A) Example 1, right eye. B) Illustration of the ganglion cell axon anatomic distribution. Courtesy of W.L.M. Alward. C) Example 2, right eye. Asterisks indicate curvilinear lesions distinct from the retinal vasculature. White arrowhead indicates retinal nerve fiber wedge defect.

The survivors of Ebola virus, one of the most aggressive hemorrhagic fevers known to man, have felt the aftereffects in the months and years since their infection. Joint and muscle pains, neurological problems, and psychiatric problems are all common to most of them.

But some of them have another distinct identifier: scars on their retinas, according to new research published by the CDC.

About 15 percent of the survivors from a military hospital in Sierra Leone showed the retinal scar that was unique to Ebola infection, according to the team from the University of Liverpool.

The evidence shows that the virus gets into the eye through the optic nerve, upon which it reaches the retina – like in West Nile Virus infections, said Paul Steptoe, the leader of the doctors undertaking the investigation in Freetown.

“Luckily, they appear to spare the central part of the eye so vision is preserved,” said Steptoe. “Follow up studies are ongoing to assess for any potential recurrence of Ebola eye disease.”

Although only transmitted through direct contact with bodily fluids, Ebola has in some senses shown to be resilient once entering the body. It can be transmitted through sperm, as researchers discovered in a handful of cases toward the end of the last big outbreak in Western Africa in 2015.

Some survivors have shown that the virus persists in the eye, as well. One notable case showed an American doctor whose eye went from a bright blue to a dilated dark green due to his sickness. The doctor survived, however.

The virus can stay tucked away in certain tissues like the brain, spinal cord and eyes because they are “immune privileged,” meaning they do not prompt the normal immune system response, because they are delicate and could not withstand the inflammation.

Another new study found that international workers almost all avoided Ebola infection, due to protective equipment they used in the field during the West African outbreak of 2013-2015. All 270 of the British and Irish workers came up negative for Ebola antibodies – indicating the precautions worked.

In the meantime, another smaller outbreak of the dreaded virus has been reported in the Democratic Republic of the Congo this week, according to United Nations health officials. Three have been reported dead.