| EBOLA - A Global Public Health Emergency |
The outbreak of Viral Haemorrhagic Fever caused by the Ebola Virus in countries in West Africa has become a global concern in recent weeks. It is a zoonotic disease and so is of concern to the veterinary community which needs to be aware of the role animal transmission plays in its epidemiology.
The Ebola Virus, first identified in 1976 in Zaire (now the Democratic Republic of the Congo) in Central Africa, belongs to the family Filoviridae which also includes the Marburg Virus – the cause of another form of haemorrhagic fever first described in Europe in the 1960’s. Ebola infection in humans results in a severely debilitating illness which has a case fatality rate of 60-90%.
The natural reservoir of the virus is the fruit bat (multiple species) from which infection may from time to time “spill over” into non-human primates (various species of apes and monkeys). The animal-human interface occurs when these animals are handled or consumed by humans – the bats in a soup, and the primates as “bush meat- allowing further “spill over” to the human population after which human to human transmission occurs.
Previous Ebola outbreaks have been usually confined to small communities in which the high mortality rate combined with strict control measures have prevented spread to wider areas. The current outbreak has spread to large population centers where control measures have been hampered by what appears to be a lack of understanding by the public, with some infected individuals avoiding proper medical care and quarantine, thereby spreading the virus more widely. Certain cultural practices have also facilitated spread.
Ebola victims become contagious when they become clinically ill and this continues even after death. Transmission occurs by direct contact with an infected individual, or their body fluids, or indirectly through contaminated materials. Aerosol transmission is NOT an established mode of transmission. Because the early clinical signs and symptoms are shared with so many other diseases, health care personnel or any care-givers are at high risk. Those involved in the burial process of the deceased are also at high risk.
The clinical course of the disease begins following an incubation period of 2 to 21 days (average 8 to 10). Initial symptoms are fatigue, severe headache, fever, myalgia and anorexia which progress to nausea and vomiting, diarrhea, dysphagia, chest and abdominal pain, a skin rash, petechiation, overt haemorrhage (internal, via body orifices), hiccups, somnolence, coma and ultimately death. The blood profile includes leukopenia, thrombocytopenia and elevated liver enzymes.
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| The Ebola virus. Photo Frederick MurphyDPA - Click the photo for a detailed WHO/PAHO document on Ebola. |
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Treatment is virtually entirely supportive. The experimental treatment known as ZMapp2 has been used in some patients in the current outbreak with variable success thus far. It is a monoclonal antibody preparation and so attempts to introduce a form of passive immunity to prevent or reduce virus activity until the victim’s own immune system can recover and eliminate the virus. Males that survive the disease may shed virus in their semen for several weeks.
The Caribbean is considered a low risk area for the introduction of Ebola, but nevertheless, given the extent of international travel, the heath authorities must exercise vigilance in the education and monitoring of travelers, as well as establishing protocols to handle any introduced cases, based on international guidelines.
EBOLA VIRUS IN DOGS
A study, conducted in Gabon in during an outbreak in 2001-2002, found that dogs exposed to Ebola by eating infected animal carcasses or licking up body fluids from infected people became infected and seroconverted yet remained asymptomatic. The conclusion drawn from the research is that dogs could potentially be a risk factor for humans during outbreaks, although there is no direct evidence of dog to human transmission. Dogs could also be monitored as a sentinel species.3 Click here for a detailed article.
For a detailed look at Ebola Virus Disease, its epidemiology, clinical course, treatment and control measures please click on the photograph above for a WHO/PAHO/CARPHA presentation1.
References:
1 - WHO/PAHO/CARPHA – Virtual Session for National Authorities in the Caribbean Sub-region
2 - Zmapp - http://en.wikipedia.org/wiki/ZMapp
3 - Allela et al. - Ebola Virus antibody prevalence in dogs and human risk : http://wwwnc.cdc.gov/eid/article/11/3/pdfs/04-0981.pdf
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| Ebola and Dogs - Is there any risk to humans? |
| The recent cases in Spain and the United States involving dogs exposed to persons infected with the Ebola virus has caused much discussion in the veterinary community. In Spain, the dog in question was euthanized sparking much outrage in the animal welfare community. In the case of Dallas, Texas, the dog was isolated and cared for while samples were collected at intervals to investigate whether or not the animal contracted the virus.
The truth is that despite all the information we have so far that is strongly suggestive that dogs play no part in the epidemiology of Ebola in humans, there remains some uncertainty as to whether or not they can actually shed virus if it gets into their system. A study carried out in Gabon in 2001-2002 during an outbreak in humans, published in 2005, determined that dogs do get exposed to the Ebola virus by consuming dead wild animals or the discharges from infected people but they do not become ill. They develop antibodies against the virus which circulate in the blood and prevent its further entry. If they do not become sick, it is highly unlikely (though not impossible) that they shed the virus in their body fluids.
Appoximately 25% of the dogs sampled were positive for antibodies. None of the dogs samped tested positive for the virus itself, whether they had antibodies or not. With no virus being found, none of those dogs could, therefore, pose a health risk to humans. Also, in all the past Ebola outbreaks, from its emergence in 1976 to the present, dogs have not figured in the process of containing and stopping the spread of the disease.
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However, given that the stakes are so high with the severe threat to human health posed by the virus, all precautions must be taken with dogs that are exposed to infected humans, particularly if they have been in contact with blood, vomitus or faecal material.
The Texas case gave excellent opportunity to begin the process of investigating whether or not it is possible for dogs to shed the virus between exposure and antibody production (seroconversion). The good news is that "Bentley", the 2-year old King Charles spaniel who was held under quarantine since his owner Nurse Nina Pham came down with Ebola has been reuinited with her follwing her recovery. "Bentley" tested negative for the virus during his period in quarantine despite having been with her when she became ill - i.e. he did not contract the virus at all.
Nevertheless, until more information is available, all in-contact dogs must be humanely managed with due diligence and care. The veterinary authorities and community must be prepared for such an eventuality with this disease or any other involving humans and animals.
PLEASE CLICK HERE for more a more detailed look at Ebola.
For information of Ebola in wildlife in endemic areas of the world, plus a look at our own bat species, please visit the Windsor Research Centre website HERE.
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