Doctors and scientists are amazed and appalled at the Scottish nurse’s relapse, which has worrying implications for the thousands of survivors in west Africa

Since 1976, when the Ebola virus was first identified, doctors racing to remote villages in African forests have thought they had a reasonable idea of what those infected were facing. The disease was grim – a hemorrhagic fever which caused copious bleeding and often death – but some people could and did fully recover. Now that is in question.

When nurse Pauline Cafferkey was admitted back into the infectious diseases unit of the Royal Free hospital in London on 9 October, nine months after recovering from Ebola, and then became critically ill, all the previous assumptions about the long-term effects of this virus had to be torn up.

Doctors and scientists are amazed and appalled. It is horrible for Cafferkey and her family, but the implications of her new illness are much more wide-reaching. The UK has a world-class health service. Cafferkey’s family were angry that the possibility that her symptoms were linked to Ebola was not immediately picked up, but even though she did not have the usual fever and vomiting, within days the virus had been identified once more and she had been flown to specialised care.

But a resurgence of illness that did not look like classic Ebola in survivors in countries with fragile or collapsed health systems, such as Sierra Leone, Liberia and Guinea or – for that matter – DRC or Uganda, which have had outbreaks in the past, would not have been recognised. It is entirely possible that people have died from Ebola complications unnoticed, months after their initial recovery, and more could still die.

Jonathan Ball, professor of molecular virology at Nottingham University, is one of those who admits to real surprise. There are a lot of unknowns about Ebola, he said, “but I don’t think anybody would for one minute have expected complications quite as serious as they certainly appear.

“What we do know is that survivors of past outbreaks do experience long-term health issues and they can be quite debilitating. They can prevent people from working but they wouldn’t have been deemed to be life-threatening.”

When somebody recovers from Ebola, it is their own immune system that does most of the work, even if they have been given – as Cafferkey had – one of the experimental drugs that are being researched. Rehydration, to combat the massive fluid loss the disease causes, and painkillers keep people going while their body’s own defences attack the virus.

Facebook Twitter Pinterest Medical personnel wheel a quarantine tent trolley containing Scottish healthcare worker Pauline Cafferkey after returning to Scotland from Sierra Leone, into a plane at Glasgow International Airport. Photograph: -/AFP/Getty Images

Those who manage to clear the virus from their system survive. But while their bloodstream, their saliva and organs such as the liver are free of the Ebola virus, there are immuno-privileged pockets where it can hide out – parts of the body that the immune system does not protect. It was recently found to linger in the fluid inside the eye. Ian Crozier, an American doctor who volunteered to work in Sierra Leone and contracted Ebola in September last year, was diagnosed with an inflammatory eye disease caused by the virus which temporarily turned his eye from blue to green. He was one of the authors of a paper published by the New England Journal of Medicine in March.

On the day that Cafferkey’s condition was said to be critical, the same journal published a paper on the length of time the virus lingers in semen. The genital tract is another immuno-privileged site. Men can carry the virus in their semen for at least nine months, revealed the paper by the World Health Organisation, the Sierra Leonean Ministry of Health and the US Centers for Disease Control. The work had been triggered by the first well-documented case of sexual transmission. Contact tracing teams in Liberia had been bemused by the death in March of a woman from Ebola who had not been near anybody with the disease. Genetic testing showed she had been infected by a recent sexual partner, who had recovered seven months earlier.

Sexual transmission is rare, the WHO hastened to say. There are around 20 suspected cases where it has occurred. If it was common, there would be thousands. WHO points to Keilahun and Kenema in Sierra Leone, which had very large outbreaks but where there have been no new cases for more than 300 days.

And yet, the discovery that the virus lingers on in semen and is capable of causing disease months later is sobering. This could have been the reason why Ebola flared up again in Liberia in June after it was thought to be over. The same thing has happened after other outbreaks in past years. With so many survivors this time, there is a new anxiety among the experts.

“It was known to some extent that the virus could persist in semen for a long time after it cleared from blood but we really didn’t know how long, and we didn’t know if it was a functional virus that could replicate and transmit infection,” said Susan McLellan, clinical associate professor of tropical medicine at Tulane University in the US.

“Cases like this, the already reported ophthalmic case, and that of the UK nurse Pauline Cafferkey ... are bringing up some really concerning possibilities about persistence of this virus that, in some situations, could lead to recurrence of outbreaks.”

Facebook Twitter Pinterest Dr Derek Gatherer of Lancaster University discusses the rarity of the Ebola virus being detected again in someone who has already overcome the disease

There are other places the virus is thought to lurk – in the prostate gland, amniotic fluid, the placenta, breast milk and the central nervous system. The latter will be the fear with Cafferkey.

Earlier this year there was another clue, this time from studies of macaque monkeys, that the virus might re-emerge from one of its hiding places and wreak more damage.

“On two occasions two of the animals appeared to have recovered from the virus and then they had a relapse which involved the brain. It was really debilitating for them,” said Ball. “It probably would have been a life-threatening illness but because it was an animal they put them to sleep – that’s what the protocol states.

“And when they looked at those animals, basically looking for any changes in the body, they didn’t see any changes in the organs that you’d associate with Ebola virus. The spleen and the liver and things like that were all fine, there were no traces of Ebola, but the brain was very heavily involved, as was the eye.”

When Cafferkey fell ill last week, it did not look like Ebola. “We’ve been reassured and there’s absolutely no reason to doubt it – that she wasn’t presenting with symptoms that would pose a risk to other people,” said Ball. “She wasn’t presenting with classic Ebola symptoms.”

NHS Scotland is taking every precaution by identifying 65 people who had physical contact recently with Cafferkey, including healthcare staff when she reported feeling ill, monitoring them for 21 days and and offering them a vaccination, as is the protocol for Ebola. Cafferkey’s illness is caused by the virus and therefore there is a theoretical risk that the virus could have been transferred to somebody else. But she was not vomiting or bleeding. “The risk to the public remains extremely low,” said NHS Scotland.

Both Cafferkey, 39, and Crozier, 44, had initially been very ill with Ebola, suffering from a higher viral load than other colleagues. That could play a part in the lingering of the virus. Nevertheless, doctors will now be on the alert for signs of long-term health problems in any of the western survivors. Unfortunately, the decimated health systems of west Africa are in no position to spot the danger signs among their many thousands of survivors.