Exactly how Ebola is and is not transmitted has been the topic of myriad articles, press conferences, pamphlets, and media discussions in the months since the outbreak in Africa worsened and the first Ebola cases hit the United States.

Public health officials have repeatedly explained that the virus is transmitted from the bodily fluids of patients, but only after they become symptomatic. The virus is not airborne and cannot be transmitted through casual contact.

The question of whether Ebola is sexually transmitted, however, has often been left out of these discussions. After all, if the virus is only transmissible when a patient has symptoms and patients who have Ebola are, more often than not, far too sick for sexual activity, it shouldn’t really be an issue.

But as more and more people survive the virus, the question is being raised again: Could a person be contagious to their sexual partner(s) even after they are “cured”?

An article in the Wall Street Journal this week suggests that might be the case.

The article tells the story of Helena Henry, an Ebola survivor in Liberia. Ebola swept through her family, killing her grandmother, two brothers, and a sister in law. When she and her mother became ill, they went to a clinic outside the capital of Monrovia where she recovered and her mother died.

After being released, she went home to her partner of 12 years and the two had sex. He became ill a week later, and two weeks after that he died. There is no way to know whether he got the virus through sexual intercourse, but Henry seems to suspect he did.

Ebola, like other viruses, is present in all bodily fluids: blood, vomit, feces, sweat, saliva, tears, urine, semen, and vaginal fluids.Those most at risk of contracting Ebola are the people who come in direct contact with a patient when she is most sick because the symptoms of the virus include vomiting, diarrhea, and unexplained bleeding.

Laboratory studies show that the virus is usually detectable at very low levels in a patient’s blood once she is experiencing fever and increases logarithmically during the acute phase of infection. The bodies of people who die from Ebola are particularly infectious.

For those who survive, the level of virus in their blood drops during their clinical recovery. Few survivors have been studied in lab settings, but the longest that any study has found detectable levels of the virus in a survivor’s blood is 21 days after the onset of symptoms.

The same is not true of semen, however. Studies have found the virus in semen as many as 101 days after symptom onset and in vaginal fluid up to 33 days after symptoms began.

Bruce Ribner, the medical director of Emory University’s Infectious Disease Unit, which treated some Ebola-infected health-care workers transported back to the United States, told the Washington Post that there have been no known cases of sexual transmission from survivors of previous outbreaks. There has been documented sexual transmission of the Marburg virus, which is described as very similar to Ebola.

The current outbreak of Ebola is the largest in history, with more than 13,500 cases and almost 5,000 deaths documented. (Both the World Health Organization and the Centers for Disease Control and Prevention estimate that the actual numbers—which include cases in which families took care of the sick and buried the dead—are much higher).

The number of cases is rising in those countries hardest hit, like Liberia and Sierra Leone. The CDC in September estimated that if nothing changes there will be 1.4 million cases in those two countries by January.

The fatality rate in this current epidemic is about 50 percent. That means about half of the people who contract the disease die, but half survive.

Some public health experts fear that survivors who return to their homes could begin to spread the virus sexually to their partners. The WHO has warned that sexual transmission could bring the virus back to places like Senegal and Nigeria, which appear free of the disease. To this end, in October the WHO began suggesting that male survivors wear condoms for at least 90 days after they first became sick.