Fear of Ebola Fever


Exotic diseases are “in” these days. In the past year we’ve had a flesh-eating bacterial disease, pneumonic plague and now Ebola fever of Zaire, which is not only making international headlines, but is also the subject of a best-selling novel, The Hot Zone, and a new Dustin Hoffman film, Outbreak. Within the last few decades, scientists have identified several viruses originating in Africa, perhaps in line with Pliny’s ancient Greek saying: “Out of Africa, always something new” (in reference to animals interbreeding at water holes). The prophesy might apply to Ebola virus, named for a river in northwestern Zaire, and one of the most recently identified of a class of viruses that cause hemorrhagic fevers. It is responsible for the recent outbreak in the city of Kikwit in Zaire, so far having caused 205 cases and 153 deaths.
Hemorrhagic fevers are zoonoses (diseases of animal origin) that spread to humans from various animals – from rodents (Bolivian and Argentinian fever), from sheep (Rift Valley fever) or from monkeys (Marburg disease).

Among the more recently uncovered causes of hemorrhagic fever, the Marburg virus, transmitted to humans from Ugandan monkeys, caused several deaths among German laboratory workers in 1969. Ebola virus of Zaire, one of the deadliest, with a fatality rate of about 75 per cent, is also thought to have been transmitted to humans from some animal (as yet unidentified). More familiar hemorrhagic fevers include dengue fever, Lassa fever and yellow fever – a known danger among ancient seafarers and visitors to West Africa. Despite an effective vaccine against it, yellow fever continues to smoulder on in tropical Africa.

Environmentalists believe the spread of disease from animals to humans, as with the hemorrhagic fevers, poses an emergent threat because deforestation and other drastic practices have disturbed the biological harmony of ancient ecosystems.

Like other hemorrhagic fevers, Ebola virus kills by attacking the lining of blood vessels, making them “leaky” and destroying blood-clotting power, which leads to severe internal bleeding. Symptoms, which surface about 10 days after infection, include flu-like malaise (headache, sore throat, joint pains) and abrupt onset of fever. Later, in about 5 days, there may be a rash, severe stomach pains and the hemorrhagic signs – bleeding from the orifices (ears, nose), gastrointestinal bleeding and vomiting black blood. Death can follow rapidly from shock and kidney or liver failure.

Although Ebola fever is a fearsome disease, the World Health Organization (WHO) officials who studied earlier outbreaks concluded that it’s not easily transmitted. The virus spreads from person to person by direct contact, mostly via face to face closeness and through blood and body fluids (saliva, urine) and is often passed from ill patients to those nursing them, especially if precautionary measures aren’t up to scratch. Ebola fever does not seem to be an airborne disease and simple infection control measures such as wearing gloves and masks, using disposable needles, and strict body-fluid precautions, often suffice to prevent transmission.

Experience from earlier Ebola fever outbreaks gives no cause for alarm in Canada. The first known outbreaks of Ebola virus disease occurred almost simultaneously in 1976 in northern Zaire and southern Sudan, in centres about 200 km apart. A second Sudanese outbreak three years later provided much of the information available about its symptoms and spread. In both the Zaire and Sudan outbreaks, action was remarkably swift. Patients were tracked, villages quarantined and the epidemic halted within eight weeks.

However, modern air travel could zip the Ebola virus from Africa to downtown Montreal, Toronto or Vancouver in 24 hours, hence public worries about it. In Canada, despite reassurances from public health officials, who have firmly stated that there’s no threat of an Ebola epidemic here, one traveller who arrived by air from Zaire was detained, and call-in TV shows have been abuzz with people worrying that Ebola virus might get a toehold in this country. Officials reiterate that this is highly unlikely as it’s not easily transmitted, and our stringent “universal precautions” practiced in hospital, with effective use of masks, gloves and gowns, can prevent spread.

Although Ebola virus was first discovered 20 years ago, there is still no vaccine or effective cure. Outbreaks have been confined to certain parts of Africa and the infection has never been detected in humans outside that continent. Although outbreaks tend to involve serious illness, milder infection might also exist and confer immunity. Public health officials repeat that, based on everything known about it, an Ebola virus epidemic in Canada is highly unlikely. Theoretically it is possible for an infected person from Africa to arrive here on a plane and spread it, but it’s improbable as people must be ill with the disease to be infectious and they would likely be picked up by immigration officials, or too sick to travel.

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Author: Piyawut Sutthiruk

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