Musa Pabai holds his son Oliver for the first time after surviving Ebola, at his home in Walakor, February 19, 2015. Pabai left an Ebola treatment centre in Liberia in November, grateful to have survived a disease that has killed nearly 10,000 people across West Africa but fearing he still could pose grave danger to the person closest to him. Pabai had stayed in Monrovia on a self-imposed exile after November, afraid that he could still infect Hannah, his girlfriend and mother of his young son, through sexual contact despite his clean bill of health. Research has shown traces of Ebola in semen of some survivors for at least 82 days after the onset of symptoms and in vaginal secretions for a much shorter period. Although there is no conclusive scientific proof these traces are infectious, anecdotal evidence of several cases in West Africa and confirmed transmission of Marburg, another viral haemorrhagic fever, have led experts to warn of the potential risk of sexually transmitted Ebola. Picture taken February 19. REUTERS/Ricci Shryock (LIBERIA - Tags: DISASTER HEALTH) 

Musa Pabai teases his girlfriend Hannah Wright, upon meeting her for the first time after surviving Ebola, at their home in Walakor, February 19, 2015. Pabai left an Ebola treatment centre in Liberia in November, grateful to have survived a disease that has killed nearly 10,000 people across West Africa but fearing he still could pose grave danger to the person closest to him. Pabai had stayed in Monrovia on a self-imposed exile after November, afraid that he could still infect Hannah, his girlfriend and mother of his young son, through sexual contact despite his clean bill of health. Research has shown traces of Ebola in semen of some survivors for at least 82 days after the onset of symptoms and in vaginal secretions for a much shorter period. Although there is no conclusive scientific proof these traces are infectious, anecdotal evidence of several cases in West Africa and confirmed transmission of Marburg, another viral haemorrhagic fever, have led experts to warn of the potential risk of sexually transmitted Ebola. Picture taken February 19. REUTERS/Ricci Shryock (LIBERIA - Tags: DISASTER HEALTH TPX IMAGES OF THE DAY) 

Kent Brantly who contracted the deadly virus Ebola, looks at his wife Amber during a press conference at Emory University Hospital in Atlanta, Georgia August 21, 2014. The American doctor along with a second American aid worker who contracted Ebola treating victims of the deadly virus in Liberia have recovered and were discharged by the Atlanta hospital that treated them with an experimental drug.
REUTERS/Tami Chappell (UNITED STATES - Tags: SOCIETY HEALTH TPX IMAGES OF THE DAY) 

Ebola survivor Nina Pham is reunited with her dog Bentley at the Dallas Animal Services Center in Dallas, November 1, 2014. Pham, the Dallas nurse treated for Ebola had an emotional reunion on Saturday with her "best friend," a King Charles Spaniel, after the pet spent the last three weeks in quarantine being monitored for the deadly virus. REUTERS/Lisa Maria Garza (UNITED STATES - Tags: ANIMALS HEALTH SOCIETY) 

U.S. President Barack Obama hugs Dallas nurse Nina Pham at the Oval Office in Washington, October 24, 2014. Obama gave a big hug on Friday to Nina Pham, the Dallas nurse who survived a bout with Ebola.
Obama met Pham in the Oval Office shortly after her release from a nearby hospital after recovering from the virus. Pham, who contracted the disease while treating a man who later died of Ebola in a Dallas hospital, had been undergoing treatment at the National Institutes of Health in Bethesda, Maryland, since Oct. 16. REUTERS/Larry Downing (UNITED STATES - Tags: POLITICS HEALTH TPX IMAGES OF THE DAY) 

Spanish nurse Teresa Romero who contracted Ebola smiles after being discharged from the Carlos III hospital in Madrid, November 5, 2014. Romero became the first person to contract Ebola outside of Africa after helping to treat a Spanish missionary who contracted Ebola in Africa and was repatriated to Spain for treatment but subsequently died. REUTERS/Andrea Comas (SPAIN - Tags: HEALTH SOCIETY TPX IMAGES OF THE DAY) 

New York Mayor Bill de Blasio hugs Dr. Craig Spencer as he is discharged from Bellevue Hospital, after being stricken by Ebola, in New York November 11, 2014. A doctor's hospital discharge on Tuesday after weeks of isolation treatment for Ebola was cheered by New Yorkers - from City Hall to the Harlem apartment building where he lives.The release of Dr. Craig Spencer, 33, who worked with Ebola patients in Guinea and had been held at Bellevue Hospital Center since he was diagnosed with the virus on Oct. 23, will mean no one in the United States is being treated for the disease, according to media reports. REUTERS/Lucas Jackson (UNITED STATES - Tags: HEALTH POLITICS TPX IMAGES OF THE DAY) 

Amber Vinson hugs caregivers before her release from Emory University Hospital in Atlanta, Georgia October 28, 2014. Vinson, 29, the second of two American nurses who became infected with Ebola while treating a Liberian man who died of the disease in Texas was released from an Atlanta hospital on Tuesday having been declared free of the virus. REUTERS/Tami Chappell (UNITED STATES - Tags: HEALTH DISASTER) 

Italian Doctor Fabrizio attends a news conference at the Spallanzani hospital in Rome January 2, 2015. Fabrizio, Italy's only Ebola patient is fully recovered and was released from hospital on Friday more than a month after being flown to Rome from Sierra Leone where he worked as a doctor treating others stricken by the disease. REUTERS/Remo Casilli (ITALY - Tags: HEALTH) 

Ebola survivor Musa Pabai walks in an Ebola Survivors Valentine's Day parade in Monrovia, February 14, 2015. Pabai left an Ebola treatment centre in Liberia in November, grateful to have survived a disease that has killed nearly 10,000 people across West Africa but fearing he still could pose grave danger the person closest to him. Research has shown traces of Ebola in semen of some survivors for at least 82 days after the onset of symptoms and in vaginal secretions for a much shorter period. Although there is no conclusive scientific proof these traces are infectious, anecdotal evidence of several cases in West Africa and confirmed transmission of Marburg, another viral haemorrhagic fever, have led experts to warn of the potential risk of sexually transmitted Ebola. Picture taken February 14. REUTERS/Ricci Shryock (LIBERIA - Tags: DISASTER HEALTH SOCIETY) 

Ebola survivor Romeo Doe poses for a picture at a clinic in Monrovia, February 1, 2015. Doe, a 29-year-old tailor who survived Ebola in Liberia, is struggling to cope with the impact of a disease that killed seven members of his family and now threatens his livelihood. Since he was released from an Ebola center in the capital Monrovia in November, pressure is rising in his eyes and affecting his vision - a complaint some doctors say is common among survivors of the West African outbreak. REUTERS/James Giahyue (LIBERIA - Tags: HEALTH) 

Felix Baez (R), a member of the International Contingent Brigade "Henry Reeve", who was infected with Ebola in Sierra Leone, poses for a photo with his wife Vania Ferrer and his son Alejandro Baez during a news conference in Havana December 6, 2014. A Cuban doctor who contracted Ebola while treating patients in Sierra Leone returned home to Cuba on Saturday, cured after 16 days in a Geneva hospital where he received an experimental treatment. Felix Baez, 43, was one of 256 Cuban doctors and nurses who went to West Africa to treat patients from the worst outbreak of the virus on record, which has killed more than 6,000 people. Felix Baez was met at Havana's Jose Marti airport by his wife, elder son and Health Minister Roberto Morales, among others, officials said. REUTERS/Yamil Lage/Pool (CUBA - Tags: HEALTH) 

An Ebola survivor and volunteer Ada Igonoh speaks at the launch ceremony of African Union support to Ebola outbreak in West Africa (ASEOWA) in Lagos December 3, 2014. REUTERS/Akintunde Akinleye (NIGERIA - Tags: HEALTH POLITICS) 

Paciencia Melgar, a Guinean nun who was cleared of Ebola after contracting the disease while on mission in Liberia, arrives for a news conference in Madrid October 20, 2014. Melgar called for a joint international fight against Ebola. REUTERS/Andrea Comas (SPAIN - Tags: DISASTER HEALTH) 

British Ebola survivor William Pooley speaks to delegates ahead of the "Defeating Ebola: Sierra Leone" conference in central London, on October 2, 2014. REUTERS/POOL/Leon Neal (BRITAIN - Tags: HEALTH POLITICS DISASTER)