Ebola Virus Disease: Understanding the Current Outbreak

Abstract and Introduction

Abstract

Ebola virus disease, caused by the filovirus Ebolavirus, leads to viral hemorrhagic fever and is fatal in many cases. Outbreaks of Ebola in sub-Saharan Africa have resulted in fatality rates of up to 90%. The 2014 outbreak in West Africa is the largest epidemic to date. The virus enters the human chain through close contact with infected primates and other animals and can be passed human to human through contact with the bodily fluids of infected persons. Currently, neither a vaccine nor an effective antiviral treatment is available for use in humans. Preventive strategies and supportive therapy are the only options available for high-risk individuals and infected patients.

Introduction

Ebola virus disease (formerly known as Ebola hemorrhagic fever) is caused by the Ebola virus.^[1] The genus Ebolavirus, along with Marburgvirus and Cuevavirus, is a member of the Filoviridae family (filoviruses or filamentous lipid-enveloped viruses).^[2] To date, five distinct species of Ebolavirus have been isolated: Sudan ebolavirus (SUDV), Zaire ebolavirus (EBOV), Tai Forest (Ivory Coast)ebolavirus (TAFV), Reston ebolavirus (RESTV), and Bundibugyo ebolavirus (BDBV).^[3]

SUDV and EBOV first appeared in two simultaneous outbreaks in 1976: one in Sudan (now South Sudan), the other in a village near the Ebola River in the Democratic Republic of the Congo (formerly Zaire).^[4] In 1994, TAFV was associated with one fatality in Cote d'Ivoire.^[4] BDBV was discovered in a 2004 outbreak in Uganda. While RESTV has been found in humans in the Philippines and the People's Republic of China, it has not been associated with any illness or deaths to date.^[1]

The 2014 outbreak is the largest epidemic to date, with the total number of cases exceeding those of all previous outbreaks combined.^[5] It has been attributed to EBOV and is the first outbreak of Ebola in West Africa (primarily Liberia, Sierra Leone, and Guinea).^[6] As of December 2014, there have been approximately 17,000 reported cases and 6,000 deaths (Table 1).^[7,8] A limited number of cases have occurred outside of West Africa. A nurse's assistant in Spain was the first person outside Africa known to have contracted Ebola in the current outbreak.^[9] In the United States, two imported cases, including one death, and two secondary cases in healthcare workers have been reported.^[7] These cases have caused widespread public and government concern about Ebola.

Table 1. The 2014 Ebola Outbreak ^a
Country	Cases	Deaths
Guinea	2,155	1,312
Liberia	7,635	3,145
Mali	8	6
Nigeria^b	20	8
Senegal^b	1	0
Sierra Leone	7,109	1,530
Spain^b	1	0
United States	4	1
TOTAL	16,933	6,002

^aCDC and World Health Organization data as of December 2, 2014. The number of patients is constantly evolving.
^bOutbreaks declared over (at least 42 days since the last negative case).
Source: References 7, 8.

Table 2. Ebola Prevention Tips
Individuals Traveling to an Affected Area
Practice careful hygiene (e.g., wash hands with soap and water or an alcohol-based hand sanitizer) Avoid contact with blood and other bodily fluids (e.g., feces, saliva, urine, vomit, semen) Do not handle an infected person's items (e.g., clothes, bedding, needles, medical equipment) Avoid funeral or burial rituals that require handling of the body Avoid contact with bats and bush meat Avoid facilities in West Africa where Ebola patients are being treated Upon return, monitor your health for 21 days and seek medical care immediately if you develop symptoms of Ebola (e.g., fever, headache, fatigue, diarrhea, vomiting, weakness, stomach pain, unexplained bleeding, joint and muscle aches)
Healthcare Professionals
Wear appropriate personal protective equipment (PPE) Isolate patients with Ebola from other patients Avoid direct, unprotected contact with the bodies of people who have died from Ebola Notify health officials if you have had direct contact with the blood or bodily fluids of an Ebola patient