The Ebola virus is leaving an indelible mark on survivors. Emerging findings, amassed by tracking unprecedented numbers of people who recovered from the disease in west Africa, suggest it causes joint pain in about half of Ebola survivors and often leads to vision problems. Meanwhile other research indicates that survivors who were pregnant when they were infected can pass the virus to the fetus. The virus has also been detected in the placenta. And semen may contain Ebola longer than was previously thought. Such discoveries are giving healthcare workers and researchers new insights into how to care for the thousands of people who survived this year’s outbreak and into potential risks for their communities.

The semen results, although preliminary, are particularly intriguing. Traces of the virus have been found in semen 284 days after infection, according to new research unveiled by the World Health Organization on August 7. The study, which included semen samples of about 100 Ebola survivors in Sierra Leone, will be submitted for peer review publication next week.

Earlier work showed that the Ebola virus persists in the testes of survivors and can be isolated from semen for up to 82 days after the onset of symptoms. More recently, traces of Ebola’s genetic material – nucleic acids – were detected in semen 199 days after the patient became symptomatic, long after he had recovered from the disease. That genetic material is a sign that virus is present but does not necessarily mean its infectious and could pass from one person to another; a whole functioning virus is needed for that. The new work, like the 199 day finding, looked at nucleic acids and thus does not conclusively prove that the virus in semen can spread disease for 284 days.

Consequently, WHO researchers plan to try to isolate the viral samples from the semen used in the study to determine if the virus is live and capable of infecting other patients. Such testing is challenging technically and requires a high-level biosafety laboratory not available in west Africa, so the samples will need to be sent to a BSL4-level laboratory, says Daniel Bausch, a physician on WHO’s Clinical Care Team for Ebola.

WHO already urges male Ebola survivors who do not know the status of their semen to abstain from sex or use condoms when engaging in sexual activity for at least six months. But the latest data raise the question of whether six months is long enough.

So far, no definitive cases of Ebola infection via sexual activity have been identified, but some have been suspected. One possible case, documented by the U.S. Centers for Disease Control and Prevention, was reported in Liberia earlier this year. In that instance, a woman infected with the virus only had one known link to Ebola: unprotected vaginal intercourse with a survivor.

WHO is already recommending the rollout of a national semen screening program in Sierra Leone and other Ebola-affected nations to help Ebola survivors avoid transmitting the virus, as well as behavioral counseling for male survivors.

Globally, there are roughly 13,000 Ebola survivors from this outbreak, says Anders Nordström, the WHO representative in Sierra Leone. “We are just at the beginning of the long, hard road” of understanding the health needs of survivors, he says.

Joint pain is another side effect demanding attention. “This can be very debilitating and a serious problem preventing people from going back to work and providing for their families,” says Bausch. The cause of the pain and why it is so common are mysteries: the virus has been found in the eyes of survivors, which could explain their vision problems, but none has been found in joints so far. Instead, it is possible that the virus triggers some sort of inflammatory response but researchers are still hunting for answers. In the case of vision impairment, which can include blindness, early medical attention such as topical medication and steroids can frequently prevent vision loss. Yet Sierra Leone only has two formally trained ophthalmologists, Bausch says.

It is not only the survivors themselves who need to be considered. Even when pregnant women manage to survive Ebola, their infants are often born disfigured and none live more than a few days. Although these women test negative for Ebola and appear disease-free, the virus still persists within the infant’s body and the placenta. “That has consequences for the potential reintroduction of the virus for people attending that birth,” says Bausch. Researchers still do not know if the virus found in those infants is infectious. Going forward, beyond explaining the medical problems facing Ebola survivors, researchers are eager to figure out how to remove the virus from areas of the body where it persists.