By Kemo Cham and Emma Farge

FREETOWN/DAKAR (Reuters) - A poster in Sierra Leone's crumbling coastal capital Freetown proclaims a message from an Ebola survivor called Sulliaman: "I feel 100 percent healthy!" Another beaming survivor Juliana says: "I am one of the safest people to be around!"

Throughout the two-year Ebola epidemic, thousands of West African survivors have been shunned by their communities, prompting governments to sponsor messages stressing their complete recovery in a bid to counter fear and paranoia.

But the case of Scottish nurse Pauline Cafferkey – the first known Ebola survivor to have an apparently life-threatening relapse – has revived concerns about the health of some 17,000 survivors in Sierra Leone, neighboring Guinea and Liberia.

Doctors and health officials in Sierra Leone told Reuters that a handful of mystery deaths among discharged patients may also be types of Ebola relapses, stirring fear that the deadly virus may last far longer than previously thought in the body, causing other potentially lethal complications.

Diagnoses have not been made, partly because of a lack of relevant medical training and insufficient equipment for detecting a virus that can hide in inaccessible corners of the body - such as the spinal fluid or eyeball. In Cafferkey's case, the virus in her brain caused meningitis.

Dr. Dan Kelly, founder of non-profit organization Wellbody Alliance who has worked on Ebola in Sierra Leone, estimates that relapsing Ebola might affect 10 percent of all recovered patients.

He said this was based on two cases, including Cafferkey's, where the live virus was detected among the roughly 20 survivors treated in Europe and the United States. Other experts have declined to give an estimate, saying it is too early to tell.

"One case reminds me of Pauline but we were unable to find a laboratory willing to test the patient before the patient died," he said. "In West Africa it (relapsing Ebola) is mostly undiagnosed, hardly treated and people are certainly dying of it."

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Confirmation of such relapses would prolong for a third year the struggle to defeat a virus that has killed nearly 11,300 people and ravaged the economies of some of the world's poorest countries.

Guinea is the only nation in West Africa that still has new confirmed cases. Liberia has been declared Ebola-free while Sierra Leone has gone 25 days without a case. But Ebola survivors continue to die under mysterious circumstances, health officials say.

Doctors at Freetown's 34 Military Hospital said they had seen two Ebola survivors return for treatment weeks after being discharged complaining of respiratory problems, including one this month. Both later died.

Officials at King's Sierra Leone Partnership also confirmed one possible relapse case in a patient with a weakened immune system in Freetown a week after recovery. Sierra Leone's National Ebola Response Center said further research on such "anomalies" is underway.

The findings may deepen the suffering of survivors, who are already fighting against stigma.

"Until there is a conclusive study, we can never be sure about this. And to be safe we must isolate them," said Freetown resident Alagie Kamara.

SURVIVOR TRAUMA

Brima Amidu, a student who survived Ebola, said his landlord has doubled his rent, in a move he believes is intended to drive him out.

"They (Western medics) treated us and if this happens to them what does it mean for us?" he said, referring to Cafferkey's relapse ten months after recovery.

Survivor Philip Koroma said counseling with a Christian group had helped him cope with ostracization. But one fellow survivor, Fatmata Conteh, was detained by police after she stoned a neighbor for calling her names, he said.

"All this is trauma. If they don't find a way to solve the problem, people could die of it," said Koroma.

There are signs that stigmatization is increasing amid evidence survivors can harbor the virus in semen for at least nine months. Liberia's last known case in June is thought to have been via sexual transmission.

Oretha, a prostitute in the red light district of Liberia's capital Monrovia, said that reports of sexual transmission had left her and other girls afraid.

"Some of our friends died. That made us be careful and use condoms. Any man that talk 'flesh to flesh', I go from them," she said, in the local Creole dialect.

In Sierra Leone's northern districts of Kambia and Bombali, new cases in recent weeks were immediately blamed on survivors.

"I'm deeply concerned by this. It is important that we all put aside fear and ignorance, and understand the facts about Ebola," said President Ernest Bai Koroma.

PARIAH, LEPER AND OUTCAST

Derek Gatherer, a virus expert at Britain's Lancaster University who has closely tracked Ebola, noted that "many survivors will not recover their former lives anyway, because of the consequences of the disease - both medical and social."

As well as stigma, many survivors complain of fatigue, joint pain and anxiety attacks.

Some aid workers say that discussing findings on the persistence of the Ebola virus could put survivors in danger. Armand Sprecher, public health specialist at medical charity Medecins Sans Frontieres (MSF), said a survivor already risked being treated "like a pariah, leper and an outcast".

"We risk making their lives miserable if we miscommunicate the actual risk we are dealing with here," Sprecher said.

Both Sierra Leone and Liberia are introducing programs to help screen survivors to see if they harbor the virus. "Operation Shield" in Sierra Leone begins regularly testing the semen of willing survivors this month.

In Guinea, where there are three known cases, government support for survivors is very basic.

Unlike earlier in the epidemic, Ebola victims and their contacts now benefit from a trial vaccine.

The World Health Organization is working with governments of the three countries to develop a survivor care plan.

"The Ebola response has already had to adapt to the extraordinary nature of this outbreak," said Adam Kucharski, an expert on infectious disease epidemiology at the London School of Hygiene & Tropical Medicine.

"The possibility of transmission long after apparent recovery poses yet another challenge."

(Additional reporting by Kieran Guilbert for the Thomson Reuters Foundation, Saliou Samb in Conakry, James Harding Giahyue and Alphonso Toweh in Monrovia, Kate Kelland in London and Tom Miles in Geneva; Writing by Emma Farge; Editing by Daniel Flynn and Susan Thomas)