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Ebola Outbreak in Guinea

By Amesh A. Adalja, MD, FACP, FACEP, April 4, 2014

The outbreak of the viral hemorrhagic fever Ebola in the nation of Guinea—the first documented appearance of this virus in western Africa—has caused much alarm, even prompting the closing of national borders to prevent the spread of disease.1 However, this outbreak thus far is demonstrating well-known characteristics of Ebola.

Ebola Zaire Strain Identified

Of the 5 known strains of Ebola, the one responsible for the outbreak in Guinea is the Zaire strain (ZEBOV), the first identified and the most deadly, with a 90% rate of fatal infection. ZEBOV was responsible for the 1976 Yambuku outbreak (the largest to date) that killed nearly 300 people and is the largest outbreak to date.1,2

Mechanism of Emergence

Although there are many questions regarding how Ebola first spills from animals to humans, once that transfer occurs, the mechanism of spread among humans has been similar in all outbreaks. Sick patients spread the virus to caregivers who are exposed to patients’ blood and bodily fluids. After death, traditional burial practices contribute to further spread of disease.2 In the case of the Guinean outbreak, it appears that an infected person brought the illness into a remote forest village.

Transport of sick people to city hospitals—in and outside of the original country—is expected to result in cases linked to the original outbreak site, but infection control is expected to limit further spread at hospitals. However, friends and family members who travel to the site of the outbreak to participate in funeral activities may contract disease and spread it to disparate locations when they return home.2

Low Tech Hygiene

Because there are no vaccines or antivirals for Ebola, the chief mechanism for halting an outbreak is containment. Because Ebola is spread exclusively via contact with blood and body fluids, limiting exposure is essential. Simple barrier protections such as gloves, gowns, surgical masks, and eye shields are sufficient for caregivers. Similarly, traditional burial practices should be modified to eliminate exposure to bodily fluids.2

Extinguishment Is Expected

As this outbreak progresses, it will not be surprising to see cases appear in neighboring nations such as Liberia and Sierra Leone. However, widespread disease with sustained human-to-human spread in the context of a documented Ebola outbreak would be unusual and not likely because, as the disease is identified, simple measures can bring it to a halt.

However, each new Ebola outbreak offers an opportunity to understand the pathophysiology of disease and the epidemiology of initial spread and provides more impetus for developing countermeasures.

References

  1. WHO. Global Alert and Response: Ebola. http://www.who.int/csr/don/archive/disease/
    ebola_haemorrhagic_fever/en/
    . Accessed March 31, 2014.
  2. Peters CJ. Marburg and Ebola viral hemorrhagic fevers. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Churchill Livingstone; 2010.