Editor note: Thankfully, a lot of the hype has already passed on this disease. This is the clinical pearl written a month ago, prior to the blog. Unfortunately, I don't think we've heard the last about Ebola, as it still comes up.
Before I start this Clinical Pearl, let me
say that Ebola is a scary disease, but, with any disease, we must put science and
fact above panic and rumor. People ask…
am I worried about Ebola for the general population? The answer is no… I am worried about diseases
that are likely to kill the general population, such as heart disease, stroke,
cancer, trauma, distracted driving, COPD, etc..
If we were to put Ebola into perspective and spend the amount of time
discussing it based on the likelihood it will kill any of us compared to the
previous diseases… Well, we would never
bring it up. Unfortunately, too much
confusion and too many myths surround this filovirus. People often say, “Ebola is a lot more likely
to kill someone than the diseases I just mentioned.” That is completely untrue. In fact, if you took patients with STEMIs or
cancer and put them in areas of Ebola outbreaks, which are remote areas of Liberia,
Sierra Leone, Nigeria, Senegal and Guinea, the mortality would probably be
higher than Ebola is now. Any disease
process in remote areas yields a high mortality rate because of unavailable
medical resources. The actual mortality
rate of Ebola in West Africa based on the first 4507 recent cases is 70
percent. The mortality rate in
hospitalized patients is 64.7 percent and 56 percent in health care workers. So, even without substantial medical care
(intravenous fluids), 30 percent of all patients survive and 44 percent of
healthcare workers survive. What is the
mortality rate of Ebola patients who contracted it in the United States? ZERO percent.
Although we have given plasma transfusions and monoclonal antibodies to
these patients, we have no evidence that we help any patient beyond supportive
care of IV fluids. Even the one patient
who was transferred to Germany, in septic shock with significant hypotension,
received 30 liters of fluids and survived.
In the first 9 months of the recent outbreak, we know a couple of things. The most common presenting symptoms are like
anything else: Fever (87%), fatigue
(76%), decreased appetite (65%), vomiting (67%), and diarrhea (65%). Less than five percent of patients had
unexplained bleeding. So, fever is not
present in 13 percent of patients, which makes it the most common yet an unreliable
finding to screen patients. These symptoms
could explain many diseases which are much more likely than Ebola.
The
transmissibility of diseases is explained by the R0 factor.
From the first 4507 patients during the recent outbreak with Ebola or
probable Ebola, this factor is 1.7-2.
The Sierra Leone type is the highest.
To put this into perspective, measles is 17-19. This represents the
number of patients who will contract the disease from one individual without
isolation. The incubation period is 11.4
days and the rate of conversion to a positive Ebola test is within 4 days. Of the twenty-seven outbreaks since 1967, none
have resulted in a pandemic.
So if
mortality is not as bad as we initially thought, many people are afraid of
Ebola because they never thought the disease would come to the United
States. This is not the first time we
have seen Ebola in the United States. In
fact it was predicted that this was going to happen. The book “The Hot Zone” by Richard Preston in
1992 predicted the reemergence of Ebola based on a monkey outbreak in Reston,
Virginia (about 10 miles from Washington, D.C.). On Oct 2, 1989, 100 monkeys were shipped via
Amsterdam through Tokyo, Tipai to New York City. They traveled down I-95 to Reston, Virgina. On November 1, 1989, the monkeys began dying
and were incorrectly diagnosed with Simian Hemorrhagic Fever, which turned out
to be Ebola Virus. The Level 4 Biosafety
Lab at Fort Dietrick correctly analyzed the tissues of the monkey. Interestingly, although no protection was
initially used in Reston, not one person contracted Ebola from the sick
monkeys. The monkeys were euthanized and
significant disinfection was performed over the next 11 days.
Another
fear is the amount of personal protective equipment (PPE) one must wear around
these patients. In fact, this is really
no different than any other potentially infectious disease when patients are
acutely ill with diarrhea or vomiting.
In many ways, it is less since Ebola is not naturally aerosolized. I would not come into contact with bodily
fluid of any acutely ill person without universal precautions. Ebola is no
different in terms of many diseases except it is less transmissible than many. We should be observing the same universal
precautions in all patients.
Quarantining
patients has been a source of great debate.
We have marked 21 days in patients as a “magical number.” Yet this is not true. Five percent of patients may show symptoms
past the 21 day mark. However we must
follow science and folks who have dealt with this process for a long time. Doctors without Borders is one of the amazing
agencies that have dealt with this disease for years and based recommendations
on science on fact. Quarantining is not
necessary unless patients are symptomatic.
Of note they also agree that, “Ebola is a hard disease to catch.” Unless you are in contact with diarrhea or
feces or vomiting, no real risk exists.
I would add that you should not come into contact with these bodily
fluids as a healthcare worker and simple gloves are not enough. I have heard of folks going into rooms with a
mask and gloves, but, like all patients, this is not universal precaution, and
the mask does nothing for Ebola, which is not aerosolized.
The host of
Ebola seems to be the fruit bat, and coming into contact with patients who have
the highest viral load or people who have recently died poses the greatest risk
of disease transmission. Additionally,
other species which are taking secretions of tissues from fruit bats seem to be
at risk as well, such as apes.
Finally, my
advice is to keep this virus in perspective.
Worry about diseases which result in bad outcomes every day. Continue to use the same precautions that
hopefully you have been using for years and do not believe rumors. Use science and the community of infectious
disease folks and evidence based articles to guide you.
Ebola Virus Disease in West Africa — The First 9 Months
of the Epidemic and Forward Projections NEJM Oct 16, 2014
Transmission dynamics and control of Ebola virus disease
(EVD): A Review
BMC Medicine 2014, 12:196 Oct 2014
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