What is an Ebola Virus?

The Ebola virus causes a lethal disease called Ebola haemorrhagic fever, Ebola, or Ebola Virus Disease, that can occur in humans and primates. Ebola virus, when analyzed by electron microscopy, appears as a long, filamentous, enveloped and non-segmented virus. The virus particles look like tubular structures, similar to tiny curled bananas, and the tubular virions appear to be ~80 nm in diameter and ~800 nm in length. Ebola viruses belong to the family Filoviridae.

So far five distinct species are known:

  • Bundibugyo,

  • Ivory Coast,

  • Reston,

  • Sudan and Zaire.

The virus genome is approximately 19 kB long and contains seven (7) linearly arranged genes.

In the spring of 2014, the World Health Organization was notified that an outbreak of a contagious or infectious disease occurred in Guinea. Characteristics of the disease are fever, severe diarrhea, vomiting, and a high fatality rate. When virologist investigated the cause of the disease, they were able to identify the Zaire Ebola virus as the causative agent. Epidemiologic studies revealed the connection of the laboratory-confirmed cases with the first known fatalities of the outbreak in 2013. 
Sequencing of the virus genome showed that Zaire Ebola virus is related to the known Zaire Ebola virus strains from the Democratic Republic of Congo and Gabon, but it is a different strain. 

Depending on the which species causes the infection, the fatality rate of the disease varies between 30 to 90%. Living conditions found in Africa as well as specific conditions in hospitals and local communities appear to be the cause for the spread of the disease between humans. 

Three Ebola virus species are known to have caused outbreaks in sub-Saharan Africa: Zaire Ebola virus, Sudan Ebola virus, and the Bundibugyo Ebola virus.  Recently, epidemics have occurred in the Democratic Republic of Congo, Sudan, Gabon, Republic of Congo, and Uganda. A similar virus called Reston Ebola virus circulates in the Philippines. This virus has caused disease in nonhuman primates but not in humans.  In addition a fifth species, the Tai Forest ebolavirus, was documented to have caused a single human infection by contact with an infected chimpanzee from the Tai Forest in Ivory Coast.

Ebola first described in 1976 has caused several epidemics since then. Ebola infections killed hundreds of people, mainly in Zaire, Sudan, Congo and Uganda. The Ebola virus and the Marburg virus belong to the Filoviridae family. Both viruses cause severe hemorrhagic fever. The fatality rate is reported to be as high as 90%. The cells infected the most are the capillary endothelium and several types of immune cells.

Symptoms of this infection include a maculopapular rash which is characterized by a flat, red area on the skin and covered with small confluent bumps. Petechiae, small red or purple spots 1 - 2 mm in size, appear on the skin. The cause is a minor hemorrhage or broken capillary blood vessels. Purpura, discolorations on the skin noticed as red or purple spots, can occur. In addition, ecchymosis, a subcutaneous purpura, dehydration and hematomas, localized collections of blood outside blood vessels, appear as well.

Ebola in West Africa

As of 18:00 on 16 April, the Ministry of Health (MOH) of Guinea has reported a cumulative total of  197 clinical cases of Ebola Virus Disease (EVD), including  122 deaths. To date, 101 cases have been laboratory confirmed, including 56 deaths, 43 cases ( 33 deaths) meet the probable case definition for EVD and  53 cases (33 deaths) are classified as suspected cases. Twenty- four (24) health care workers have been affected with 13 deaths.  Clinical cases of EVD have been reported from Conakry (47 cases, including 16 deaths), Guekedou (117/80), Macenta (22/16), Kissidougou (6/5), Dabola (4/4) and Djingaraye (1/1).

Mali: The Ministry of Health (MOH) of Mali has today reported that the clinical samples on the 6 suspected cases have tested negative for ebolavirus.  

Liberia: As of 16 April the Ministry of Health and Social Welfare (MOHSW) of Liberia has reported a cumulative total of 27 clinical cases of EVD, including 13 deaths attributed to EVD. One new suspected case reported yesterday from Nimba County has been laboratory confirmed as a case of Lassa fever. Two patients remain hospitalised and 33 contacts remain under medical observation. The MOHSW commissioned a new ebolavirus laboratory today in collaboration with Metabiota.

Sierra Leone: On 15 April, the Ministry of Health and Sanitation (MOHS) provided a consolidated report of surveillance activities conducted in that country from 19 March onwards. A total of 12 suspected cases have been identified during that period. “

[Source: http://www.afro.who.int/en/clusters-a-programmes/dpc/epidemic-a-pandemic-alert-and-response/outbreak-news/4100-ebola-virus-disease-west-africa-16-april-2014.html]



Sylvain Baize, Delphine Pannetier, Lisa Oestereich, Toni Rieger, Lamine Koivogui, N’Faly Magassouba, Barrè Soropogui, Mamadou Saliou Sow, Sakoba Keïta, Hilde De Clerck, M.D., Amanda Tiffany, Gemma Dominguez, Mathieu Loua, Alexis Traoré, Moussa Kolié, Emmanuel Roland Malano, Emmanuel Heleze, Anne Bocquin, Stephane Mély, Hervé Raoul, Valérie Caro, Dániel Cadar, Martin Gabriel, Meike Pahlmann, Dennis Tappe, Jonas Schmidt-Chanasit, Benido Impouma, Abdoul Karim Diallo, Pierre Formenty, Michel Van Herp, and Stephan Günther; Emergence of Zaire Ebola Virus Disease in Guinea — Preliminary Report. This article was published on April 16, 2014, at NEJM.org. DOI: 10.1056/NEJMoa1404505. Copyright © 2014 Massachusetts Medical Society. http://www.nejm.org/doi/full/10.1056/NEJMoa1404505