For the communities in
Guinea, Sierra Leone, and Liberia where Ebola took the greatest toll last year,
the worst is over. After claiming 11,000 lives, the fatal virus has finally
begun to retreat. Numbers of new Ebola cases are dwindling. But for some of the
survivors, the
50 percent or so of the infected who pull through—Ebola’s effects
still linger.
Thousands of Ebola survivors have resumed their regular lives, but
many of them are still traumatized, struggling to process the horrors they’ve
seen and rejoin societies that have shunned them. But the disease’s
aftereffects aren’t just psychological. Many survivors are now returning to
clinics complaining of mysterious symptoms: chronic headaches, debilitating
joint pain, even eye problems that can progress to blindness. Some doctors in
the region have begun calling the suite of problems “post-Ebola syndrome,” and
they’re developing clinics devoted to caring for Ebola survivors.
But it’s not easy to treat a
syndrome that has no definition.
While epidemiologists have long suspected that Ebola might cause
lingering health effects, it’s been nearly impossible to study them, because
Ebola survivors were uncommon. “Up until now, it really has been a very rare
disease,” says infectious disease researcher Danielle Clark. Earlier this year,
Clark published astudy in Lancet Infectious diseases based on an Ebola
outbreak before last year’s epidemic: a small resurgence in Uganda in 2007. She
was able to track down 49 survivors nearly three years after the outbreak, and
found that many of them experienced the same eye problems and joint pain
described by 2014 survivors.
But that data isn’t robust enough
to convince the medical community that every ailment described by an Ebola
survivor is a direct result of the infection. “Many of the symptoms being
reported by survivors are non-specific and could be due to consequences of Ebola
virus disease or other diseases,” says Michael Sneller, an infectious disease
researcher with the NIH. Plenty of other diseases common in west Africa, like
Lassa fever or malaria, could be causing the physical symptoms. And symptoms
like fatigue, anorexia, and insomnia could be caused by post-traumatic stress
disorder.
But this most recent outbreak was
unusual in the number of people who survived it—a new population to study. With
15,000 or so confirmed survivors in west Africa, epidemiologists ought to be
able to nail down which symptoms are caused by Ebola infection. But it won’t be
easy. In the wake of the epidemic, most outreach workers and researchers on the
ground were so focused on treating infections and preventing transmission
that it might be impossible to follow up with survivors.
So now researchers are trying to play catch up. And their best shot at
defining the causal relationship between Ebola and these symptoms is a
study being run by the NIH in collaboration with Liberia’s Ministry of Health. Launched in June, the
PREVAIL study will ask 1,500 survivors about their symptoms and perform
physical exams—eye tests, neurological evaluations, blood draws—to track
symptoms. (Another part of the study is testing an Ebola vaccine in Liberia,
and the study will also track survivors to see if they remain immune to future
Ebola infection or can transmit the virus to close contacts.)
Importantly, PREVAIL won’t just
follow survivors. It will also follow control subjects who were never infected.
If post-Ebola syndrome is real, that control group should report significantly
fewer symptoms. “This type of study of survivors, to my knowledge, has not and
is not being done for the current epidemic,” says Sneller, who is one of the
lead NIH researchers on the study.
Of course, all of this research does nothing for clinics for Ebola
survivors—like the one that just opened at Redemption Hospital in Monrovia,
Liberia. Right now, doctors can only treat the symptoms that they see, like
with anti-inflammatory drugs for headaches and joint pain. “We have to find out
why these people have long-term symptoms,” says neurologist Adnan Qureshi, who
recently published a survey of symptoms in Ebola survivors in Clinical
Infectious Diseases.
Right now, researchers have two
main theories. The first is perhaps the scarier one: That the virus itself
hasn’t completely cleared. Tests for Ebola look for antigens to the virus in an
infected person’s blood serum, so while a person may be declared Ebola-free and
sent home, the test could be missing reservoirs of the virus in other parts of
the body. “There may be virus persisting, and direct tissue damage could result
from the infection itself,” says Clark. Ebola virus definitely hides out in the
testes and eyes—that’s why male survivors are encouraged to refrain from sex or
use condoms for three months after their infections clear up. Hypothetically
reservoirs could exist elsewhere in the body, like in the synovial fluid in the
joints.
The second explanation is an
autoimmune response. After the infection has cleared, the immune system may
remain active, attacking anything in the body it perceives as foreign. That
idea jibes pretty well with the joint pain that is a common complaint
among survivors: “Joints have always been very vulnerable to overactive immune
systems,” explains Qureshi. In that case, immunomodulating drugs might be the
best treatment.
Unfortunately, until the PREVAIL
data comes in—nailing down which symptoms, if any, are linked directly to the
viral aftermath—clinicians can’t know which idea is right. For now, clinics
like those at Redemption Hospital have to make do with the treatments they
have—and wait.
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