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Ebola: A Veterinarian’s Perspective

By Kim Everson, DVM

Who needs made-up Halloween horrors when this year a real-life monster is stalking the world? I’m talking about Ebola. It’s a worldwide source of terror. You can’t attend a high school football game or turn on the evening news without overhearing speculation, worry and opinion about the nightmarish disease. This virus of epidemic proportions has even affected the veterinary healthcare field. In Spain, an infected nurse’s pet dog was destroyed by court order in an effort to control the potential outbreak; while in Texas, an infected nurse’s dog has been placed under quarantine in military custody for 21 days (ending November 3rd) to observe for signs of infection.

Ebola Hemorrhagic Fever is a terrifying disease, and a healthy dose of fear is essential to stop a potential pandemic in its tracks. However, ignorance of the facts makes fearful things more dangerous. If we lose focus on what we know about the disease and how to control it, if we begin flailing around blindly in our effort to combat it we risk doing more harm than good.

In my effort to understand Ebola and explain it to my circle of friends, family and clients, I have learned some important facts. Let’s start with the basics:

Ebola Hemorrhagic Fever (EHF) is a severe, contagious disease affecting humans and non-human primates

This cartoon character suffers from “the suds,”
a fictional virus withsymptoms not unlike influenza.

(i.e., monkeys, apes). Symptoms of EHF include fever, severe headache, muscle pain, diarrhea, weakness, abdominal pain, unexplained bleeding or bruising. These symptoms appear within 2-21 days after exposure (the average is 8-10 days). There is no cure for EHF, but with supportive care and good immune response patients can recover. Once recovered, the infected person is no longer contagious; however, Ebola virus has been detected in semen up to 3 months later making abstinence during this period important to controlling an outbreak situation.

EHF is caused by Ebola virus, first recorded in 1976 in Sudan and Zaire and named for the Ebola River in Zaire. There are five known strains of Ebola virus–ZEBOV, SEBOV, BEBOV, REBOV, TEBOV–each with different levels of infectiousness and deadliness. Of the various strains, ZEBOV (Zaire) and SEBOV (Sudan) appear to be the most dangerous to human health with fatality rates ranging from 53-90%.

There is much we don’t know about how an Ebola virus outbreak starts, but researchers have discovered that the virus can exist in animals. Fruit bats are suspected to be a natural reservoir for the Ebola virus, meaning bats could carry and shed the virus but not be made sick by it. Monkeys and primates can be infected and spread the virus; Ebola virus is highly fatal in these animals. Human exposure has been documented after eating or coming into close contact with infected monkeys and apes.

In experimental settings, horses, guinea pigs and goats have been infected with Ebola virus and may develop mild symptoms of the illness. Pigs have been shown to become mildly ill from ZEBOV and can transmit the virus to non-human primates; there is no good data on whether pigs (or other domestic animals) can transmit the Ebola virus to humans. Researchers have questioned whether Ebola virus could be transmitted by biting insect vectors (such as mosquitoes), but solid evidence is lacking. Once a human has become infected through a “spillover event”–exposure to an infected animal–spread from person-to-person can occur rapidly.

Close contact with dogs is not currently
believed to be a risk factor for Ebola virus exposure
but precautions with pets in contact with confirmed
Ebola victims is likely to continue.

Scientific study of Ebola virus in Africa reveals that dogs can develop an immune response to Ebola virus. Dogs are exposed to the virus in the same way people are–by direct contact with contaminated bodily fluids via the eyes, nose, mouth, mucus membranes or breaks in the skin. Once the canine immune system detects the virus, it begins making antibodies against it. This does not mean the dog has become infected, however. Dogs have not been observed to become ill, and scientists have not been able to isolate Ebola virus from dogs who have been exposed. There is no evidence at this time that dogs are a source of infection for humans.

As disparaged as vaccination is in certain (very loud) circles, I have heard many concerned citizens ask hopefully about the development of an Ebola virus vaccine. It seems a reasonable request, and a strong assumption, that with enough funding and talent a vaccine can be readily developed to protect ourselves from this fearsome illness. Yet with all our medical and scientific advances, we have not been able to develop vaccines for many other deadly and debilitating viruses (including, for example, HIV) and not for want of trying!

People who have recovered from Ebola virus have been shown to have antibodies for up to ten years later. Antibodies are part of our immune system’s natural defense against infection. Vaccination stimulates the production of antibodies without actually causing the disease to prepare our immune defenses against the possibility of exposure. In other words, through immunization, our immune system is given a “heads up” about a contagious disease so if it encounters it in the future the body’s defense system is ready to destroy it rapidly. Not all antibody production is protective, however. People and animals exposed to Lyme bacteria, for example, develop detectable antibodies to the bacteria, but these antibodies do not prevent future infection. (Lyme vaccination in dogs works in a different way from other vaccines and is highly effective.)

Still, the World Health Organization has announced the release of two experimental vaccines against Ebola virus by the end of 2015. These vaccines will be administered to those on the front lines handling EHF outbreaks. The safety and effectiveness of the vaccines has not yet been proven, so officials warn it is no “magic bullet”. Proper quarantining and protective gear will continue to be vital tools in the containment of this disease.

With public awareness and aggressive oversight by public health organizations, Ebola virus is unlikely to

Proper application of simple and proven contagion
control measures will reduce the spread of minor
and deadly viruses alike in the U.S.

become an epidemic in the United States. The attention this disease has aroused among researchers and financiers in recent weeks suggests we will be learning a lot about this deadly virus in a short period of time and “knowledge is power.” As a veterinarian trained in infectious disease control, I was encouraged to learn the Ebola virus is not very hardy in the environment, remaining viable for hours as opposed to days or weeks. Also, Ebola virus is readily inactivated with common disinfectants. I do not mean to say less emphasis should be placed on the use of personal protective equipment (PPE) among health care workers simply because Ebola virus is fragile in the environment. Also I believe strict quarantining should be enforced as needed to control an outbreak. However, for most of us common concerned citizens, the practice of good hygiene including thorough and frequent hand-washing as well as common sense measures like avoiding school, work and travel when feverish or showing signs of “the suds” is the best protection against picking up and/or spreading minor colds or serious influenza much less Ebola virus.

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