Ebola virus has once again figured out how to surprise and confound humans. It attacked the eyes of a doctor weeks after he had been deemed cured and virus-free.

The doctor, 43-year-old Ian Crozier, had contracted Ebola while working in Sierra Leone and was flown back to Emory University Hospital in Atlanta last September, desperately ill.

Weeks of intensive treatment saved Crozier's life. But soon after leaving the hospital, he started to have problems with his eyes. There were a burning sensation, a feeling that there was something stuck in his eye and sensitivity to light.

One month later, Crozier suddenly suffered blurred vision, pain and inflammation in his left eye. Eye doctors call this uveitis, an inflammation inside the eye that can cause blindness.

When doctors tested the aqueous humor, the watery substance that sits atop the eye of the lens, it tested positive for Ebola.

They were able to save the eye, but it took months for the man's vision to recover.

"This case highlights an important complication of [Ebola] with major implications for both individual and public health," write the authors of the report, which was published Thursday in the New England Journal of Medicine.

The doctors don't know just how Ebola is able to hide and replicate in the eyes when the body has defeated it elsewhere. But the eyes are body parts that evolved to have adaptations in the immune system that discourage inflammation but might also make them more vulnerable.

"If you had a mosquito bite on your retina it would blind you," says Dr. Russell Van Gelder, chairman of ophthalmology at the University of Washington Medicine and president of the American Academy of Ophthalmology. So eyes are "immune privileged"; they don't respond to threats with inflammation like the skin and other body parts do.

"So it's not surprising that when a virus gets in the eye, it can hide from the surveillance of the immune system and bide its time," Van Gelder tells Shots. Cytomegalovirus and herpes viruses also can cause hard-to-fight eye infections.

Male testes are another immune-privileged organ, and it looks like semen can harbor Ebola virus for many months. Last week NPR's global health and development blog reported on a woman who was infected after having sex with an Ebola survivor.

Having an Ebola eye infection isn't likely to pose a similar risk, Van Gelder says. The doctor's tears and conjunctiva tested negative for the virus, even while it was replicating inside the eye.

it's not the first time that Ebola has turned up in people's eyes long after the fact. After an Ebola outbreak in the Democratic Republic of Congo in 1995, 15 percent of 71 people being studied came down with eye problems while convalescing.

Because tens of thousands of people survived the Ebola outbreak in Africa, there could be thousands of people who risk blindness from delayed eye infections, Van Gelder says.

"This could become a major health issue much in the way that in the height of the AIDS outbreak in the 1980s, cytomegalovirus retinitis was a big issue," he adds. "About one-third of people would go blind before they died of HIV."

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Transcript

ROBERT SIEGEL, HOST:

Dr. Ian Crozier was successfully cured from Ebola last year - or so he thought. He had fought for his life. Dr. Crozier became ill with the disease in Sierra Leone, where he'd been volunteering in an Ebola treatment unit - an ETU. After six weeks at Emory University Hospital in Atlanta last fall, his blood was declared Ebola free.

What he and his physicians did not know was that the virus was still lurking in his left eye. Yesterday, at a national ophthalmology conference, he and his doctors discussed his case, and their account was published in the New England Journal of Medicine. Dr. Crozier joins us now from Denver. Thanks for - thanks for joining us.

IAN CROZIER: Good afternoon, Robert. It's good to be with you.

SIEGEL: And tell us, when did you first realize after you'd been declared Ebola-free that there was something wrong with your eye?

CROZIER: I had very mild occasional burning and occasional light sensitivity in the eye, but really wasn't having very many symptoms. In fact, it was hearing that there were some early reports of survivors from Sierra Leone who were developing some eye symptoms that made me pay attention. And that's when I first met the team at Emory ophthalmology.

SIEGEL: How did they figure out that it was Ebola?

CROZIER: Well, initially when they first saw me, my examination was normal. I was having no symptoms, although I did have dark scars, I would say, on the back of my eye - on the retina. They were unusual, and it was a month later that I presented with eye symptoms and was diagnosed with an inflammatory process in the eye that we call uveitis.

SIEGEL: At the risk of making our listeners feel queasy right now, how does one go about the testing what's inside your eye?

CROZIER: Well, four days after the onset of my symptoms, my eye pain and redness was getting worse. So on a Sunday afternoon at the Emory Eye Clinic, the ophthalmologist, which is Steve Yeh, put a 30 gauge needle in through the white part of my eye and directed it towards the dark space right above the pupil. And he took a small amount of fluid from that eye.

I remember at the time turning to those in the room and saying surely this is not going to be Ebola. But just in case it is, remember what it feels like to be right in the middle of a paradigm shift. And a few hours later, the PCR came back positive.

SIEGEL: Wow.

CROZIER: And it came back positive at higher levels than it had been even in my blood.

SIEGEL: What did you think or fear at that moment when you had that diagnosis?

CROZIER: It was obviously odd to realize that this virus that I'd already sort of had an intimate dance with had been squatting in the eye ever since without paying rent for the past three months. It was a shock to realize it. And as the process evolved, it became very difficult to understand in what essentially was a new disease how best to care for the eye.

SIEGEL: What does one do at that point? I mean, you'd already gone through all of the hydration or whatever one does for having Ebola in your bloodstream. What's the treatment for Ebola in the eye?

CROZIER: We began to look at this as a standard uveitis. There are other infections that cause inflammation in the eye. And one of the cornerstones of those treatments is to give topical anti-inflammatory steroids. Despite that, the eye continued to evolve, and eventually we needed to make a decision about whether we could try and change the playing field given the fact that the eye was getting worse and I was going blind basically over the next weeks.

SIEGEL: Dr. Crozier, you're being admirably clinical about this right now with the benefit of it all being in the past. But what a relationship you had with this disease by that time - you had gone to Africa as a volunteer for the World Health Organization to treat people. You had contracted Ebola. You had been declared free of Ebola. You are now battling Ebola in the eye. Do you feel as though you have some personal relationship with this disease - some grudge match with this disease?

CROZIER: (Laughter) Yeah, I suppose - I suppose there's an element of that for sure. You know, I'll tell you, as the eye process evolved - of course, it's a shock to find it in the eye - but as - as it - the disease evolved, you know, some other things happened. My pressure went down, my eye was changing shape. And then I had a bizarre color change in the eye. And though, of course, you worry more about losing your sight, I found that actually quite a personal affront.

SIEGEL: Your blue eyes turned green at some point.

CROZIER: Yes, my left eye suddenly turned quite a bright green.

SIEGEL: This is rare, obviously, but is there any reason to believe that there aren't hundreds of people in West Africa who survived Ebola but who still have the virus in the eye?

CROZIER: Yes, I'm really glad you asked that question. You know, I suppose I struggle a bit with an unwarranted but still present survivor's guilt when I think about the access to care that I received. And in one sense, I'm extremely grateful to the WHO and the State Department for enabling that evacuation. I would have been dead in a week had that not happened. On the other sense, you know, I'm haunted by my patients. And so it's particularly important to me to make sure that the technical expertise and what we learned around my eye was able to very quickly and nimbly make its way back to African eyes.

SIEGEL: How does it feel as a doctor to moonlight as a famous case in this instance - be a famous patient for once?

CROZIER: You know, I've begun to talk about this space as a dual citizenship of sorts. And it's a very interesting space, Robert, I'm still learning about, but it is extremely gratifying if the care that I received can make a difference back on the ground in West Africa. I'd been there for years, and so it's really important to me that the northern sort of expertise that I've been offered and have benefited from is able to be quickly and in an agile way translated back on West African land.

SIEGEL: Dr. Crozier, thank you very much for talking with us.

CROZIER: You're very welcome. My pleasure.

SIEGEL: Dr. Ian Crozier spoke with us from Denver.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.

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