Tag Archives: ebola virus infection

Ebola virus the unwelcome traveler?

map of ebola virus outbreaks

Map of current (red) and prior (beige) Ebola virus outbreaks

Despite local and international efforts to halt the Ebola virus epidemic, an  outbreak that started in south-eastern Guinea in March, 2014 has since spread to other parts of Guinea, and to neighboring countries Sierra Leone and Liberia (2,3). Bats, a local food delicacy, are considered the primary culprit for the current Ebola virus outbreak. African fruit bats are a natural host of Ebola virus and transmit the virus directly to humans who handled an  infected animal or indirectly through  intermediary hosts, such as monkeys,  apes, or pigs. These animals were themselves infected after coming in contact with bat saliva or feces. Since Ebola virus is relatively stable, humans risk infection when slaughtering an infected animal, consuming infected foods (blood, milk, or undercooked meat) or coming in close contact with soiled bedding or personal items from a sickened individual (6).

Ebola virus infection (1,8)

adapted from Muyembe-Tamfum, J.J. et al 2012, ‘Ebola virus outbreaks in Africa: Past and present’, Onderstepoort Journal of Veterinary Research 79(2), Art. #451, 8 pages. http://dx.doi. org/10.4102/ojvr.v79i2.451

Late stage Ebola virus infection. Red rash from dermal bleeding (red box)

Depending on the strain of the virus, Sudan or Zaire, Ebola virus will kill between 25% and 90% of those infected. With a long asymptomatic incubation period (2 to 21 days) and initial presentation of flu-like symptoms (fever, headache, nausea, muscle ache, sore throat and malaise) that mimic more common diseases such as malaria or typhoid, Ebola virus often goes unrecognized until late into its disease spread.

Ebola virus infection begins with high fever, headache and fatigue that intensifies over an ensuing 1 to 6 days. These initial symptoms are soon followed by bouts of diarrhea, abdominal pain and vomiting. By day 8 a pseudo-remission stage is often seen, with patient health looking to improve and patients may feel well enough to eat solid food. It is also at this time that patients may recover and survive the disease.* If the infection is not stopped, patient will soon display increase respiratory distress (labored breathing and cough, throat and chest pain), evidence of internal bleeding (bloody diarrhea or vomit, bleeding gums or nosebleeds) and red or purple skin rash appear that most resembles rash seen during measles virus infection. Without intervention, the patient soon succumbs to cardiovascular collapse, multiple organ failure, coma and eventual death.

* Of note: Men who recover from the disease can still transmit the virus through their semen for up to 7 weeks post illness.

The Ebola virus (1,8)

Ebola virus picture

Diagram of Ebola virus particle

When viewed by electron microscopy, Ebola virus particles vary in both appearance and size. Virion lengths range from 130 nanometers (nm) to 14,000 nm and particles appear as U-shaped , circular or a long filaments. The virus is comprised of a single negative strand RNA genome that is encased in a helical shaped ribonucleoprotein (RNP) complex and composed of nucleocapsid protein (NP) and lesser amounts of virus protein (VP) 30. The RNP complex along with Ebola RNA polymerase complex ( protein L and VP35) is surrounded by matrix proteins VP 40 and VP 24, an outer lipid membrane derived from the host cell plasma membrane and a covering of virus glycoprotein.

Bush meat importation (4,5)

Kindu Congo Bushmeat market 2009 provided by Terese Hart

Sales of Bush meat in an African open market

The desire to bring back the “taste of home” or to illegally sell Bush meat has resulted the smuggling of thousands of pounds of Bush meat annually into the US and Canada. Bush meat , named for meat that is obtained from wild animals of the African ‘bush, is often smuggled on planes in passenger luggage, shipped in the mail, or at the commercial level, embedded with dried fish or meat shipments. From a number of studies and anecdotal evidence of Customs seizures, black market sales of Bush meat in 2007 was estimated to be on the order of 7-8 tons per month. Customs agents discover on average one passenger per week attempting to bring Bush meat back from Africa and into the United States. Bush meat seized is shown to come from butchered monkeys, apes or bats and is often packaged a  raw and uncooked. Bio-testing  of Bush meat has found DNA evidence of disease causing viruses and bacteria including monkeypox, the HIV-related simian immunodeficiency virus (SIV), herpesvirus B or tuberculosis.

Conclusion

The ease with which one can fly from West Africa to New York in less than 18 hours, the desire to bring Bush meat home to share with friends and family and a fatal disease which has both a long incubation time and initial symptoms that mimic commonly virus infections places a high probability that an Ebola virus epidemic will occur somewhere in a US city in the not too distant future. It will only be with increased border vigilance both here and in Africa to stop importation of Bush meat that we might avert such a crisis.

Citations

1. Brown, K. S., A. Silagh, and H. Feldmann. 2008. Ebolavirus, p. 56-65. In: B. W. J. Mahy and M. H. V. Van Regenmortel (eds.), Encyclopedia of Virology. 3rd ed. Elsvier.

2. Global Alert and Response, W. 2014. Ebola virus disease in Guinea. http://www.who.int/csr/don/2014_03_23_ebola/en/

3. Global Alert and Response, W. 2014. Ebola virus disease, West Africa – update. http://www.who.int/csr/don/2014_07_24_ebola/en/

4. Goldman, R. 2007. Bushmeat: Curse of the Monkey’s Paw. http://abcnews.go.com/Health/story?id=2952077&page=1

5. Harris, D. and A. Karamehmedovicd. 2009. Bushmeat Sold on Open Market in U.S. http://abcnews.go.com/Nightline/IntoTheWild/bushmeat-africa-sold-open-market-us/story?id=9312518.

6. Media centre, W. 2014. Ebola virus disease, fact sheet 103. WHO. http://www.who.int/mediacentre/factsheets/fs103/en/

7. Muyembe-Tamfum, J.J., Mulangu, S., Masumu, J., Kayembe, J.M., Kemp, A. and Paweska, J.T., 2012, ‘Ebola virus outbreaks in Africa: Past and present’, Onderstepoort Journal of Veterinary Research 79(2) Art#451

8. Olinger, G., T. W. eisbert, and L. E. Hensley. 2008. Filoviruses, p. 198-205. In: B. W. J. Mahy and M. H. V. Van Regenmortel (eds.), Encyclopedia of Virology. 3rd ed. Elsvier.

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