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16. Ebola Virus Disease anja.boehme.pdf


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isolate patients, and observe strict barrier nursing procedures with the use of a medical-rated
disposable face mask, gloves, goggles, and a gown at all times, strictly enforced for all medical
personnel and visitors. The aim of all of these techniques is to avoid any person’s contact with the
blood or secretions of any patient, including those who are deceased.
Vaccines have successfully protected nonhuman primates; however, the six months needed to
complete immunization made it impractical in an epidemic. To resolve this, in 2003, a vaccine using
an adenoviral (ADV) vector carrying the Ebola spike protein was tested on crab-eating macaques.
The monkeys were challenged with the virus 28 days later, and remained resistant. In 2005, a vaccine
based on attenuated recombinant vesicular stomatitis virus (VSV) vector carrying either the Ebola
glycoprotein or Marburg glycoprotein successfully protected nonhuman primates, opening clinical
trials in humans. By October, the study completed the first human trial; giving three vaccinations over
three months showing capability of safely inducing an immune response. Individuals were followed for
a year, and in 2006, a study testing a faster-acting, single-shot vaccine began. This study was
completed in 2008.
Vaccines
There are currently no Food and Drug Administration-approved vaccines for the prevention of EVD.
Many candidate vaccines have been developed and tested in various animal models. Of those, the
most promising ones are DNA vaccines or are based on adenoviruses, vesicular stomatitis Indiana
virus (VSIV)[or filovirus-like particles (VLPs) as all of these candidates could protect nonhuman
primates from ebolavirus-induced disease. DNA vaccines, adenovirus-based vaccines, and VSIVbased vaccines have entered clinical trials.
Contrary to popular belief, ebolaviruses are not transmitted by aerosol during natural EVD outbreaks.
Due to the absence of an approved vaccine, prevention of EVD therefore relies predominantly on
behavior modification, proper personal protective equipment, and sterilization/disinfection.
In 6 December 2011 the development of a successful vaccine against Ebola for mice were reported.
Unlike the predecessors it can be freeze-dried and thus stored for long periods in wait for an
outbreak. The research will be presented in Proceedings of National Academy of Sciences.
In Endemic Zones
The natural maintenance hosts of ebolaviruses remain to be identified. This means that primary
infection cannot necessarily be prevented in nature. The avoidance of EVD risk factors, such as
contact with nonhuman primates or bats, is highly recommended, but may not be possible for
inhabitants of tropical forests or people dependent on nonhuman primates as a food source.
During outbreaks
Since ebolaviruses do not spread via aerosol, the most straightforward prevention method during
EVD outbreaks is to avoid direct (skin-to-skin) contact with patients, their excretions and body fluids,
or possibly contaminated materials and utensils. Patients ought to be isolated but still have the right to
be visited by family members. Medical staff should be trained and apply strict barrier nursing
techniques (disposable face mask, gloves, goggles, and a gown at all times). Traditional burial rituals,
especially those requiring embalming of bodies, ought to be discouraged or modified, ideally with the
help of local traditional healers.
In the Laboratory
Ebolaviruses are World Health Organization Risk Group 4 Pathogens, requiring Biosafety Level 4equivalent containment. Laboratory researchers have to be properly trained in BSL-4 practices and
wear proper personal protective equipment.
Treatment
There is currently no Food and Drug Administration-approved ebolavirus-specific therapy for EVD.
Treatment is primarily supportive in nature and includes minimizing invasive procedures, balancing
fluids and electrolytes to counter dehydration, administration of anticoagulants early in infection to
prevent or control disseminated intravascular coagulation, administration of procoagulants late in
infection to control hemorrhaging, maintaining oxygen levels, pain management, and administration
of antibiotics or antimycotics to treat secondary infections. Hyperimmune equine