Review on Ebola Virus Disease: Its Outbreak and Current Status

Abstract

Background: Ebola virus disease (EVD) is caused by Ebola viruses (EBOV), members of the group of hemorrhagic fevers and it is one of the most dangerous infection diseases with mortality rates up to 90%. Ebola was firstly described in 1976 and since then occurred sporadically in Central Africa. Till 2014, twenty four outbreaks were described, but the number of deaths not exceeding 300 per outbreak. As of May 20, 2015 the cumulative number, suspected, and laboratory-confirmed cases attributed to Ebola virus was 26, 969, including 11,135 deaths.

Pathogenesis: Ebola Viruses do not replicate through cell division, but instead insert their own genetic sequencing into the deoxyribonucleic acid (DNA) of the host cell and subsequently hijack all cellular processes, including transcription and translation. In essence, the host cell becomes a factory of viral proteins. As new viral capsules are formed, they bud from the host cell, taking a part of the host cell’s outer membrane, thus cloaking themselves against detection by the host’s immune system. In some cases, the patient’s immune system can produce enough antibodies to defeat the infection. With EVD, the virus can often reproduce so rapidly that the immune system never catches up.

Transmission: The natural reservoir of EBOV is believed to be bats, particularly  fruit  bats,  and  it  is  primarily  transmitted  between  humans  and  from  animals  to humans  through  body  fluids.

Clinical presentation: Symptoms  of  EVD include  abrupt  onset  of  fever, myalgias,  and  headache  in  the  early  phase,  followed  by  vomiting,  diarrhea  and possible  progression  to  hemorrhagic  rash,  life-threatening  bleeding,  and  multi organ failure in the later phase.

Treatment: There are no approved treatments or vaccines available for EVD until today; the mainstay of therapy is supportive care.  However, there are a bunch of therapeutic approaches on the track which could have the real impact on control and prevention of this global threat.  High fatality, combined with the absence of treatment and vaccination options, makes Ebola virus an important public health pathogen and biothreat pathogen of category A.

Keywords: Ebola virus, Ebola virus disease, hemorrhagic fever, outbreak, epidemic, supportive care, reservoir, West Africa.