Learn about the evolving Ebola epidemic and its various aspects including disease prevention, management and treatment, response to the epidemic, ethical considerations, and the post-Ebola global health landscape.
Convalescent Serum
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En provenance du cours de Emory University
Ebola Virus Disease: An Evolving Epidemic
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Prevention, Treatment, and Response
Upon completion of this module, learners will be able to: List the different types of therapeutics for Ebola Virus Disease. Recognize the factors critical to the creation of a successful Ebola vaccine. Define plasma and recognize its importance in the Ebola treatment process. Discuss the response of various international actors to the Ebola epidemic. Recognize the role of communications both in terms of community level in West Africa, as well as at Emory University.
Rencontrer les enseignants
Dabney P. Evans, PhD, MPHAssistant Professor
Hubert Department of Global Health. Rollins School of Public Health. Director, Center for Humanitarian Emergencies.
Carlos del Rio, MDChair
Department of Global Health at the Rollins School of Public Health
Hi, I'm Annie Winkler, an assistant professor in the Department of Pathology
and Laboratory Medicine at Emory University.
I specialize in transfusion medicine and blood banking, and today, I'm going
to speak with you about the collection and transfusion of Ebola convalescent plasma.
Without an approved vaccine or other proven treatment for Ebola virus disease,
patient management has been limited to supportive care measures,
such as intravenous fluid and electrolyte replacement and
medications to control nausea, vomiting and diarrhea, in
addition to personal protective equipment to prevent transmission of the virus.
Despite these interventions, the 2014 West Africa ep,
epidemic has become the deadliest occurrence of the disease,
killing five times more individuals than all other known Ebola outbreaks combined.
Since the first report, on March 23, 2014,
over 25,000 cases have been reported with an approximate 40% mortality rate,
according to estimates from the Centers for Disease Control and
the World Health Organization as of March 31st, 2015.
While devastating, this epidemic has allowed for the opportunity to
investigate experimental agents for the prevention and treatment of Ebola
virus disease in clinical trials both in and outside of West Africa.
One of the first experimental agents used to treat patients
with Ebola virus disease in the United States and in Europe was called ZMapp,
which is a drug cocktail comprised of monoclonal antibodies,
targeted against portions of the Ebola virus.
However, until the current outbreak, ZMapp had never been tested in humans,
and had only been proven effective in animal models, using guinea pigs and
rhesus macaque monkeys.
A limited supply of ZMapp was used to treat seven individuals
infected with Ebola virus disease, of which two unfortunately died.
And in August 2014, this limited supply of ZMapp that was initially available for
animal studies, was completely exhausted.
As a result of the successful treatment of the first two patients in the US
to ever be treated for Ebola virus disease, physicians at the University of
Nebraska and Emory University sought other potential immune therapies for
the treatment of two additional patients with Ebola that were evacuated from
West Africa for treatment in the United States in mid-September.
Plasma, which is the pale yellow liquid component of the blood,
which contains mostly water, proteins, including these antibodies,
clotting factors, electrolytes, and other components,
was collected from a US survivor and transfused to a patient with Ebola virus
disease who was being treated at the University of Nebraska Medical Center.
This plasma from survivors, or what we termed convalescent plasma,
was subsequently used to treat multiple patients in United States and Europe
with Ebola virus disease, and is currently in clinical trials in West Africa.
However, the efficacy has never been proven in humans.
Convalescent plasma has been cited as a potential therapy for
viral infection dating back to 1918 during the Spanish Influenza A pandemic.
Since that time, use of convalescent plasma as what we call passive immune
therapy has been used for the treatment of other viruses, such as Cytomegalovirus, or
CMV, Hepatitis B, rabies, varicella or chickenpox, in addition to others.
However, the use of convalescent plasma in patients with Ebola has not been
investigated, nor do we understand the immune response of survivors.
The only information we knew about antibodies from survivors
were from previous epidemics of a different strain of Ebola.
What was known about Ebola passive immune therapy was from a 1995 outbreak
of Ebola in Kikwit, in the Democratic Republic of Congo.
Nine patients received whole blood transfusions from survivors,
which includes a small amount of plasma which contains antibodies
in addition to other blood components such as red cells, white cells, and platelets.
Following transfusion, seven other recipients survived, which accounted for
a much lower case fatality rate of 12.5%, compared to the overall
rate of 70 to 80% for the 1995 and previous epidemics.
While Ebola antibodies may have played a role, the authors of the study could not
exclude that better supportive care could have accounted for
the survival benefit in these patients.
Despite this limited evidence, we proceeded with collection and
transfusion of Ebola convalescent plasma for
patients with Ebola virus disease treated in the United States.
The first step was always to ensure that a survivor was available and
willing to donate, as blood donation is entirely voluntary.
Following coordination of the donor and the procedure, an Emergence,
Emergency Investigational New Drug application was filed with the Food and
Drug Administration for each donor and recipient pair.
This was a necessary step because the survivors do not qualify for
a traditional blood donation criteria
by current requirements because of recent infection with Ebola virus and for
most survivors, recent travel to a malaria endemic area in Africa.
In addition, the product of interest,
Ebola convalescent plasma, is not an FDA-approved blood product.
In speaking with the FDA, we provided information regarding clinical history and
course of the recipient, treatment plan including plasma donor characteristics and
procedure, monitoring of the donor and
the recipient, how we were to consent both, and use of alternative therapies.
Following issuance of an EIND number, we were able to contact
our institutional review boards for emergency approval to proceed.
This is a map of collections of transfusions of six of ten
US patients who received Ebola convalescent plasma.
While it may not appear as complex, collecting and shipping plasma
was very challenging, especially when there were four patients admitted
simultaneously in the United States for treatment of Ebola virus disease.
However, despite these challenges,
we have been able to collect over 16 liters of Ebola convalescent plasma
from seven donors during 12 collections, six of which are US survivors.
Over the past few months, investigators at the University of Nebraska and Emory,
with support of the Cerus Corporation,
have developed the infrastructure to collect Ebola convalescent plasma.
Our protocol includes collection of plasma during a procedure called apheresis,
which separates the plasma from the remaining components of the blood,
such as red cells, and returns them to the donor.
In addition, because the donors do not meet eligibility criteria for
donation in the United States, we use a technology
called the INTERCEPT Blood System, which is manufactured by Cerus.
This device allows us to remove any residual pathogens in the plasma,
such as malaria.
This is a very important step to ensure that we are providing
the safest blood product possible to a patient with Ebola virus disease.
Like traditional blood donation,
laboratory tests are performed to determine the blood type of the donor, and
to assess for any infectious diseases, such as HIV, Hepatitis C, or Hepatitis B.
For research purposes,
we are also working with investigators at the US Army Medical Research Institute
of Infectious Diseases to characterize the donor antibody response and
the ability of the donor's antibodies to actually neutralize the Ebola virus.
The plasma is then stored in Emory in preparation for distribution as needed for
transfusion to a patient with Ebola virus disease.
Similar to what is being done in the United States,
a trial of convalescent plasma funded by the Bill and
Melinda Gates Foundation is ongoing in Liberia, where, following a short period
of time after discharge from the treatment facility, the survivor can become a donor.
Once the plasma is collected, it is pathogen inactivated,
similar to the procedure performed at Emory, stored, and used for treatment.
Given the decline in patients in Liberia, since the trial start,
only six subjects have been enrolled, and we are not likely to find the answers
we need regarding the efficacy of convalescent plasma from this study.
Simultaneously, a separate trial is ongoing in Guinea, and
given the unfortunate continued number of new cases,
we may have a better idea of the efficacy of Ebola convalescent plasma.
To date, they have enrolled over 50 patients.
In addition, similar efforts are ongoing in Sierra Leone.
Because of the few patients receiving treatment in the United States,
many people ask what will happen to the plasma
if it's not actually transfused to patients.
If the plasma is transfused, it can be used as a starting material for
many things, which includes a lyophilized or powder plasma that could be stored for
a longer period of time, maybe up to decades, and used for a future outbreak.
It may be also for manufacture of a purified antibody or
hyperimmune immunoglobulin.
However, this process may take many liters of plasma to begin.
The plasma can also be used as laboratory samples to standardize laboratory tests
used throughout the world for measurement of Ebola antibodies, in an effort
led by the World Health Organization Ebola Antibody as a working group.
And, lastly, the plasma can be used as material that can be used in animal models
to specifically evaluate the clinical efficacy of Ebola convalescent plasma.
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