Ebola virus belongs to the Filoviridae family can cause epidemics of haemorrhagic fever with high case-fatality rates. Ebola virus (EBOV) is a select agent, World Health Organization Risk Group 4 Pathogen. Ebola virus has five species, including Zaire Ebolavirus( ZEBOV / EBOV), Sudan eoblavirus (SUDV / SEBOV); Taï Forest ebolavirus (formerly Côte d'Ivoire ebolavirus, abbreviation:TAFV / CIEBOV), Bundibugyo ebolavirus (BDBV / BEBOV) and Reston ebolavirus (REBOV / RESTV).
The 2014 Ebola Outbreak is cause by Zaire Ebolavirus( ZEBOV / EBOV) and is currently ongoing in West Africa, including Guinea (the country of origin) and the east, the capital, Conakry, and the neighboring countries of Sierra Leone and Liberia. Four cases have occurred in Nigeria, in travelers from infected areas, and subsequently in health care workers. This outbreak is the most severe in recorded history in regards to both the number of human cases and fatalities. Till 6 August 2014, Ebola virus has caused 1711 people infected and 932 dead.
Ebola virus (EBOV) first emerged in the form of two nearly simulta-neous outbreaks, one due to Sudan ebolavirus and the other to Zaire ebolavirus. The first outbreak was due to Ebola Sudan. As its name implies, it occurred in Sudan, near the border with the Democratic Republic of the Congo (DRC) (formerly Zaire), mainly affecting the towns of Nzara and Maridi, between June and November 1976. The mortality rate was 53% (150 of 284 victims), which is characteristic of theSudan subtype. The second outbreak was due to E. Zaire. It occurred in DRC, near the borders with Sudan and the Cen-tral African Republic (CAR), between August and Novem-ber 1976. This previously unknown disease was named for the river Ebola, which flows past Yambuku. The mortality rate was 89% (284 deaths among 318 declared victims).
The third outbreak (the second due to Sudan ebolavirus) occurred between July and October 1979 in the same region as the first in Nzara, Sudan. This outbreak was less extensive than the first, affecting 34 people and killing 22 (mortality 65%).
After a 15-year period in which no further cases wer recorded, Ebola re-emerged in 1994 for a 3-year period. This new phase was marked by the identification of a new sub-type, E. Ivory Coast (Taï Forest ebolavirus), and by an escalation of outbreaks due to Zaire ebolavirus. Taï Forest ebolavirus was the first and only human case observed in West Africa, and the only case clearly attributed to E. Ivory Coast (Taï Forest ebolavirus). Finally, three further outbreaks, all due to Zaire ebolavirus, occurred in northeast Gabon, the first in Mekouka between 1994 and 1995, the second in Mayibout in early 1996, and the third in Booué between 1996 and 1997.
Between January and July 1995, the virus killed 256 of its 315 victims, a mortality rate (81%) characteristic of the Zaire subtype.
In February 1996, Zaire ebolavirus has affected 31 people and caused 21 deaths (mortality rate 67.7%).
The third outbreak, the Booué outbreak, occurred between October 1996 and March 1997. This outbreak, with 60 cases and 45 deaths occurring over a 6-month period, was noteworthy for its wide geographic range.
During the period of 2000–2004, there is an emerging geographic pattern of Zaire ebolavirus and resurgence of Sudan eoblavirus. The other outstanding feature of this period is the occurrence of Ebola outbreaks in large animal species (mainly gorillas and chimpanzees).
The first outbreak during this period was the Mekambo outbreak, which occurred between October 2001 and May 2002. During these eight months, there were several outbreaks. The source of the first outbreak has not been identified, while the second resulted from the handling of a chimpanzee carcass. The last clearly identified outbreak occurred on 27 March 2002 when hunters from Grand-Etoumbi village (on the northern axis) butchered and ate a gorilla carcass they had found in the forest.
Simultaneously, a second outbreak occurred.The origin of this outbreak is unknown. Sequencing of viral isolates confirmed the exist-ence of several concurrent outbreaks.
The third outbreak, confirmed by laboratory tests, again affected the region of Mbomo in RC, between December 2002 and May 2003. This outbreak involved 143 cases and 128 deaths.
Two outbreaks of E. Sudan occurred during this period. The site of the first was in Uganda between October2000 and January 2001, causing 173 deaths among its 425 victims (mortality rate 40.7%). This was numerically thelargest of all recorded outbreaks, and comprised three foci,one in the immediate area of Gulu, one in the town of Masindi, and another smaller outbreak in Mbarara, where a military patient carried the outbreak. In contrast, the second outbreak was the smallest ever recorded, with 17 cases and seven deaths during May and June 2004; this mortality rate (41%) is characteristic of Sudan ebolavirus.
On 30 November 2007, a new strain of Ebola virus broke up in the Uganda and finally was named Bundibugyo ebolavirus. The epidemic came to an official end on 20 February 2008. While it lasted, 149 cases of this new strain were reported, and 37 of those led to deaths.
During this period, there were some other outbreaks that caused people dead.
This outbreak caused by Sudan ebolavirus. The fist outbreak in July 2012 in the Kibaale District led to 13 people death (70% mortality rate).Then it spread to more villages. On 8 August, the Ugandan Ministry of Health recorded 23 probable and confirmed cases, including 16 deaths. By 21 August, the WHO reported a total of 15 cases and 10 fatalities. By 13 September 2012, the WHO revealed that the virus had claimed 32 lives and that the probable cause of the outbreak was tainted bush meat hunted by local villagers around the towns of Isiro and Viadana.