Ebola epidemiology and demographics

Epidemiology
Outbreaks of EVD have mainly been restricted to Africa. The virus often consumes the population. Governments and individuals quickly respond to quarantine the area while the lack of roads and transportation helps to contain the outbreak. EVD was first described after almost simultaneous viral hemorrhagic fever outbreaks occurred in Zaire and Sudan in 1976. . EVD is believed to occur after an ebolavirus is transmitted to a human index case via contact with an infected animal host. Human-to-human transmission occurs via direct contact with blood or bodily fluids from an infected person (including embalming of a deceased victim) or by contact with contaminated medical equipment such as needles. In the past, explosive nosocomial transmission has occurred in underequipped African hospitals due to the reuse of needles and/or absence of proper barrier nursing. Aerosol transmission has not been observed during natural EVD outbreaks. The potential for widespread EVD epidemics is considered low due to the high case-fatality rate, the rapidity of demise of patients, and the often remote areas where infections occur.

Distribution
This is a map of the distribution of ebola in Africa.




 * Distribution of Ebola and Marburg virus in Africa (note that integrated genes from filoviruses have been detected in mammals from the New World as well). (A) Known points of filovirus disease. Projected distribution of ecological niche of: (B) all filoviruses, (C) ebolaviruses, (D) marburgviruses.

Outbreaks
Ebola outbreaks have been restricted to Africa, with the exception of Reston ebolavirus. The International Committee on Taxonomy of Viruses currently recognizes four species of the Ebola: Zaire virus (ZEBOV), Sudan ebolavirus (SEBOV), Reston ebolavirus (REBOV), and Cote d'Ivoire ebolavirus (CIEBOV).