West Africa Ebola Outbreak 2014

Ebola virus disease (EVD) is a sporadically occurring and high mortality disease caused by Ebola viruses (EBOV). There are five closely related strains of Ebola viruses. Four of them commonly cause disease in humans: Ebola virus (ZEBOV, formally known as Zaire); Sudan virus (SUDV); Tai Forest or Côte d’Ivoire virus (TAFV); and Bundibugyo virus (BDBV). The fifth, Reston virus (RESTV), has been caused disease only in nonhuman primates (monkeys, gorillas, and chimpanzees) [1, 2].

EBOV together with Marburg and Lloviu viruses make up the filoviruses family. All of the members of Filoviridae have similarities in the structure of virion, genome formation and most of them cause fatal haemorrhagic fevers in humans [3]. The illness included symptoms such as fever, headache, and malaise at onset, with profuse vomiting and diarrhea occurring 2-4 days later, haemorrhagic symptoms occur in severe cases. Ebola is one of the most lethal diseases. Mortality rate ranges from 53-88%. Ebola viruses are endemic to Africa and to the Philippines. Due to fact that Ebola is highly pathogenic disease with such as high mortality, must be conducted in a Biosafety Level 4 laboratory (together with Marburg virus, Lassa virus, Crimean-Congo haemorrhagic fever and various other haemorrhagic diseases).

EVD was firstly described in 1976 during two concurrent outbreaks [4, 5]. It was given the name ‘Ebola’ after the small river near the catholic mission of Yambuku, the epicentre of the 1976 Ebola haemorrhagic fever outbreak [13]. Between 1976 and 2014 twenty-four epidemics of EVD were verified, mostly caused by ZEBOV in Equatorial Africa [2]. These were typically occurs in Sub-Saharan Africa on limited area with number of cases from tenth to hundreds and number of victims not exceeding three hundred. West Africa Ebola outbreak 2014 (WAEO) is currently the largest one in human history [6, 7]. There are several differences between WAEO 2014 and previously occurred outbreaks.

The differences are in size of geographically spread, number of cases and duration. Previously occurred outbreaks are mostly limited on villages closely related with rainforests and do not widespread to the large area, but WAEO exceeded not only countries borders (four countries of Equatorial Africa: Guinea, Liberia, Sierra Leone and Nigeria), but also the continent borders (Spain and America) [6]. Number of laboratory confirmed human cases were lower (maximum 425, Sudan 2000-2001) and duration of previously described outbreaks were shorter than one year. WAEO 2014 crossed also these established rules. The number of reported cases is almost 20,000, and it is assumed that outbreak takes more than one year, because number of cases and deaths still increase.

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