Ebola Viral Disease Outbreak — West Africa, 2014

Meredith G. Dixon, MD; Ilana J. Schafer, DVM


Morbidity and Mortality Weekly Report. 2014;63(25):548-551. 

In This Article

Characteristics of EVD

EVD is characterized by the sudden onset of fever and malaise, accompanied by other nonspecific signs and symptoms such as myalgia, headache, vomiting, and diarrhea. Among EVD patients, 30%–50% experience hemorrhagic symptoms.[4] In severe and fatal forms, multiorgan dysfunction, including hepatic damage, renal failure, and central nervous system involvement occur, leading to shock and death. The first two Ebolavirus species were initially recognized in 1976 during simultaneous outbreaks in Sudan (Sudan ebolavirus) and Zaïre (now Democratic Republic of the Congo) (Zaïre ebolavirus)[5] Since 1976, there have been more than 20 EVD outbreaks across Central Africa, with the majority caused by Ebola virus (species Zaïre ebolavirus), which historically has demonstrated the highest case-fatality rate (up to 90%).[3]

The wildlife reservoir has not been definitively ascertained; however, evidence supports fruit bats as one reservoir.[6] The virus initially is spread to the human population after contact with infected wildlife and is then spread person-to-person through direct contact with body fluids such as, but not limited to, blood, urine, sweat, semen, and breast milk. The incubation period is 2–21 days. Patients can transmit the virus while febrile and through later stages of disease, as well as postmortem, when persons contact the body during funeral preparations. Additionally, the virus has been isolated in semen for as many as 61 days after illness onset.

Diagnosis is made most commonly through detection of Ebola virus RNA or Ebola virus antibodies in blood.[5] Testing in this outbreak is being performed by Institut Pasteur, the European Mobile Laboratory, and CDC in Guinea; by the Kenema Government Hospital Viral Hemorrhagic Fever Laboratory in Sierra Leone; and by the Liberia Institute of Biomedical Research. Patient care is supportive; there is no approved treatment known to be effective against Ebola virus. Clinical support consists of aggressive volume and electrolyte management, oral and intravenous nutrition, and medications to control fever and gastrointestinal distress, as well as to treat pain, anxiety, and agitation.[4,5] Diagnosis and treatment of concomitant infections and superinfections, including malaria and typhoid, also are important aspects of patient care.[4]

Keys to controlling EVD outbreaks include 1) active case identification and isolation of patients from the community to prevent continued virus spread; 2) identifying contacts of ill or deceased persons and tracking the contacts daily for the entire incubation period of 21 days; 3) investigation of retrospective and current cases to document all historic and ongoing chains of virus transmission; 4) identifying deaths in the community and using safe burial practices; and 5) daily reporting of cases.[4,7,8] Education of health-care workers regarding safe infection-control practices, including appropriate use of personal protective equipment, is essential to protect them and their patients because health-care–associated transmission has played a part in transmission during previous outbreaks.[4,9]