Preliminary results of a study into persistence of the Ebola virus in body fluids show that some men's semen test positive for the virus nine months after onset of symptoms, far longer than previously known.

The report, published in the New England Journal of Medicine, provides the first results of a long-term study being jointly conducted by Sierra Leone, the World Health Organisation and the US Centres for Disease Control and Prevention.

It provides further evidence that Ebola survivors need continued monitoring for six to 12 months to meet the health risks and to ensure their partners are not exposed to potential virus lingering in the body.

“Ebola survivors face an increasing number of recognised health complications,” said CDC director Tom Frieden. “This study provides important new information about the persistence of Ebola virus in semen and helps us make recommendations to survivors and their loved ones to help them stay healthy."

Research findings

The focus on semen follows past research that showed persistence of the Ebola virus in the body fluid.

A total of 93 men all over 18 years from Sierra Leone, one of the three West African countries at the epicentre of the Ebola outbreak since late 2013, provided semen samples that were tested to detect the presence of Ebola virus genetic material. The men enrolled in the study between two and 10 months after their illness began.

For men who were tested in the first three months after infection, all showed positive results for Ebola in the semen.

More than half of the men who were tested between four to six months after diagnosis were positive, while a quarter of those tested between seven to nine months after their illness began were positive. The men were given their test results along with counselling and condoms.

However, why some study participants' semen had cleared the fragments of Ebola virus earlier than others remains unclear. The US Centres for Disease Control and Prevention in Atlanta is conducting further tests of the samples to determine if the virus is live and potentially infectious.

Recommendations

Following the study results, WHO indicates that until more is known, the more than 8,000 male survivors of Ebola in Guinea, Sierra Leone and Liberia need appropriate education, counselling and regular testing.

WHO recommends that until a male Ebola survivor’s semen has twice tested negative, he should abstain from all types of sex or use condoms when engaging in sexual activity. Hands should be washed after any physical contact with semen. In the current West African outbreak, continued vigilance to identify, provide care for, contain and stop new cases, are key strategies on the road to achieving zero cases.