(CNN) -- Two American missionaries infected
with the deadly Ebola virus were given an
experimental drug.
Shortly after, Dr. Kent Brantly and Nancy Writebol
were flown separately from Liberia to Atlanta's
Emory University Hospital -- the first human
patients with Ebola to ever come to the United
States.
Writebol was released from the hospital Tuesday.
On Thursday morning, Brantly walked out of that
same hospital with no signs of the virus in his
system, doctors say.
Their recoveries seem to offer hope for those
fighting the largest Ebola outbreak in known
history. More than 2,400 people have been
infected by the virus, according to the World
Health Organization, and it's killed more than
half.
But ZMapp is not an approved
treatment for Ebola; in fact, no
approved, proven treatment exists. So
governments, aid organizations and
scientists around the globe are racing
to find a way to stop the virus.
Here are answers to questions about
Ebola patients and treatments for the
disease.
1. Are Brantly and Writebol cured?
Mostly. For Ebola patients to leave
isolation, two blood tests had to come
back negative for the Ebola virus. So
their bodily fluids, like blood, sweat
and feces, are no longer infectious.
"Nancy is free of the virus, but the
lingering effects of the battle have left
her in a significantly weakened
condition," Writebol's husband, David
Writebol, said in a statement.
Some doctors believe the virus can
remain in vaginal fluid and semen for
up to several months, according to
WHO. Dr. Bruce Ribner, an infectious
disease specialist at Emory, said there
is no evidence Ebola has ever been
transmitted this way, but the risk was
discussed with both patients.
2. Are they now immune to Ebola?
Doctors believe surviving Ebola leaves you
immune to future infection. Scientists have found
that people who survive Ebola have antibodies in
their blood that would provide protection against
that strain of the virus in the future, and possibly
against other strains as well.
But, as you can imagine, they haven't tested this
theory by infecting survivors with the virus again.
There are four Ebola strains known to infect
humans; the Zaire ebolavirus causing the current
outbreak is the most common.
3. Who else has been given ZMapp?
The Ebola drug was flown to Spain to give to a
priest named Miguel Pajares, who had contracted
the virus in Liberia. Pajares died on August 12.
It's unclear if he was given the drug before he
died.
ZMapp appears to be helping three Liberian
health care workers who were given the
experimental drug. They have shown "very
positive signs of recovery," the Liberian Ministry
of Health said earlier this week . Medical
professionals treating the workers have called
their progress "remarkable."
4. Who makes the drug?
The drug was developed by the biotech firm Mapp
Biopharmaceutical Inc., which is based in San
Diego. The company was founded in 2003 "to
develop novel pharmaceuticals for the prevention
and treatment of infectious diseases, focusing on
unmet needs in global health and biodefense,"
according to its website .
Mapp Biopharmaceutical has been working with
the National Institutes of Health and the Defense
Threat Reduction Agency, an arm of the military
responsible for countering weapons of mass
destruction, to develop an Ebola treatment for
several years.
5. How does ZMapp work?
Antibodies are proteins used by the immune
system to mark and destroy foreign, or harmful,
cells. A monoclonal antibody is similar, except
it's engineered in a lab so it will attach to specific
parts of a dangerous cell, according to the Mayo
Clinic , mimicking your immune system's natural
response. Monoclonal antibodies are used to treat
many different types of conditions.
Sources told CNN the medicine given to Brantly
and Writebol abroad was a three-mouse
monoclonal antibody, meaning that mice were
exposed to fragments of the Ebola virus, and then
the antibodies generated within the mice's blood
were harvested to create the medicine.
However, the drug can also be produced with
proteins made from tobacco plants. ZMapp
manufacturer Kentucky BioProcessing in
Owensboro provided limited quantities of this kind
of the drug to Emory, according to company
spokesman David Howard.
6. Did doctors know it would work in humans?
No. The drug had shown promise in primates, but
even in those experiments, just eight monkeys
received the treatment. In any case, the human
immune system can react differently than
primates', which is why drugs are required to
undergo human clinical trials before being
approved by government agencies for widespread
use.
These cases will be studied further to determine
how the drug worked with their immune systems.
7. Are there other Ebola treatments out there?
Several experimental drugs are in development,
but none has been effective in humans.
The market for these drugs is small -- Ebola is a
rare disease, almost completely confined to poor
countries -- so funding for drug development has
come largely from government agencies.
In March, the NIH awarded a five-year, $28
million grant to establish a collaboration between
researchers from 15 institutions who were
working to fight Ebola. On Wednesday, Wellcome
Trust and the United Kingdom's Department for
International Development announced money for
Ebola research will be made available from a
$10.8 million initiative .
8. Will ZMapp or these other drugs be given to
more Ebola patients?
An ethics panel convened by the World Health
Organization concluded it is ethical to give
experimental drugs during an outbreak as large
as this one, but that doesn't mean it will happen.
Rolling out an untested drug during a massive
outbreak would be very difficult, Doctors Without
Borders says. Experimental drugs typically are not
mass-produced, and tracking the success of such
a drug, if used, would require extra medical staff
where resources are already scarce.
In an opinion article published in the journal
Nature this week, epidemiologist Oliver Brady
says up to 30,000 people in West Africa would
have so far required treatment in this outbreak if
it was available.
9. What about an Ebola vaccine?
For the record, "vaccine" and "treatment" are not
interchangeable terms. A vaccine is given to
prevent infection, whereas treatment generally
refers to a drug given to a patient who has
developed symptoms.
There are several Ebola vaccines in development.
The Canadian government has donated between
800 and 1,000 doses of an experimental Ebola
vaccine to WHO. The drug, called VSV-EBOV, is
Canadian-made and owned, having been
developed by the National Microbiology
Laboratory.
It's never been tested on humans "but has shown
promise in animal research," the agency says. We
don't know if the vaccine has been given to
anyone on the ground.
No comments:
Post a Comment