Ebola Virus Infection Clinical Presentation
- Author: John W King, MD; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD more...
In patients who have Ebola virus infection, 2 types of exposure history are recognized: primary and secondary.
A history of primary exposure usually involves travel to or work in an Ebola-endemic area, such as the Democratic Republic of Congo (DRC; formerly Zaire), Sudan, Gabon, or Côte d’Ivoire. A history of exposure to tropical African forests is more common in patients with primary exposure to Ebola than is a history of working within cities in the same region.
Because no natural reservoir of Ebola has been identified, the relation between specific exposure to potential arthropod, animal, or plant vectors and disease remains unproven. Bats are now considered a likely candidate species for a natural reservoir.
Secondary exposure refers to human-to-human or primate-to-human exposures. In each major outbreak, medical personnel or family members who cared for patients or those who prepared deceased patients for burial were at very high risk. Also at risk for infection are animal care workers who provide care for primates. This group includes patients who experienced infection with Reston ebolavirus, as evidenced by antibody production, but did not develop Ebola virus disease.
An advisory from the CDC’s Health Alert Network on the evaluation of patients for Ebola by health-care personnel and health officials include the following :
Ebola should be considered as a possibility in patients who present with fever, myalgia, severe headache, abdominal pain, vomiting, diarrhea, or unexplained bleeding or bruising
For any patient presenting with fever or other symptoms consistent with Ebola, inquiries should be made as to whether the patient traveled to an Ebola-affected country in the 21 days before the onset of illness
Patients who report having travelled to an Ebola-affected country and who are exhibiting Ebola symptoms should be isolated in a private room with a private bathroom, and standard, contact, and droplet precautions should be implemented
Local and state health departments should be notified immediately
According to the advisory, individuals at the highest risk for Ebola infection include the following :
Anyone who has had direct contact with the blood and body fluids of an individual diagnosed with Ebola
Anyone who has had close physical contact with an individual diagnosed with Ebola
Anyone who lived with or visited an Ebola-diagnosed patient while the patient was ill
Physical findings depend on the stage of disease at the time of presentation. Early in the disease, patients may present with fever, pharyngitis, and severe constitutional signs and symptoms. A maculopapular rash, more easily seen on white skin than on dark skin, may be present around day 5 of infection and is most evident on the trunk. Bilateral conjunctival injection is also common.
Late in the disease, patients often develop an expressionless facies. At this point, bleeding from intravenous (IV) puncture sites and mucous membranes is common. It is worth noting that in the 1976 Ebola outbreak, bleeding was seen in most cases, whereas in the 1995 Ebola outbreak, bleeding occurred in only half of the patients. Myocarditis and pulmonary edema also are seen in the later stages of the disease. Terminally ill patients often die tachypneic, hypotensive, anuric, and in a coma.
Human infections with African-derived Ebolavirus species are characterized by an incubation period that is typically 3-8 days in primary cases and slightly longer in secondary cases. However, cases with incubation periods of 19 and 21 days have been observed.
The onset of clinical symptoms is sudden. Severe headache (50%-74%), arthralgias or myalgias (50%-79%), fever with or without chills (95%), anorexia (45%), and asthenia (85%-95%) occur early in the disease.
Gastrointestinal (GI) symptoms, including abdominal pain (65%), nausea and vomiting (68%-73%), and diarrhea (85%), soon follow. Evidence of mucous membrane involvement includes conjunctivitis (45%), odynophagia or dysphagia (57%), and bleeding from multiple sites in the GI tract. Bleeding from mucous membranes and puncture sites is reported in 40%-50% of patients.
A rash, which in survivors desquamates during convalescence, is seen in approximately 15% of patients. Terminally ill patients often are obtunded, anuric, tachypneic, normothermic, and in shock.
Although the mechanism is unclear, hiccups were noted in fatal cases of Ebola virus disease in both the 1976 and the 1995 outbreaks in the DRC. In the 1995 Ebola virus outbreak in Kikwit, DRC, tachypnea was the single most discriminating sign that separated survivors (none of whom had tachypnea) from patients who died (37% of whom had tachypnea).
Ocular complications were reported in 3 (15%) of 20 survivors of the 1995 Ebola outbreak in the DRC. Patients reported ocular pain, photophobia, increased lacrimation, and decreased visual acuity. All had documented uveitis, and all improved with topical application of 1% atropine and steroids.
Survivors of Ebola virus disease have developed the following late manifestations:
Asymmetric and migratory arthralgias
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- Table 1. History of Sudan Ebola Virus Outbreaks
- Table 2. History of Zaire Ebola Virus Outbreaks
- Table 3. History of Tai Forest (Ivory Coast, Côte-d’Ivoire) Ebola Virus Outbreaks (No Deaths Reported)
- Table 4. History of Reston Ebola Virus Outbreaks (No Deaths Reported)
- Table 5. History of Bundibugyo Ebola Virus Outbreak
|Year||Location||Reported Cases, No.||Deaths, No. (%)|
|Data from Centers for Disease Control and Prevention and World Health Organization.
* Occurred after laboratory accident.
|Year||Location||Reported Cases, No.||Deaths, No. (%)|
|Jan 1996 to Apr 1996||Gabon||37||21 (57)|
|Jul 1996 to Jan 1997||Gabon||60||45 (74)|
|1996||South Africa (acquired in Gabon)||1||1 (100)|
|Oct 2001 to Mar 2002||Gabon||65||53 (82)|
|Oct 2001 to Mar 2002||DRC||59||44 (75)|
|Dec 2002 to Apr 2003||DRC||143||128 (89)|
|Nov 2003 to Dec 2004||DRC||35||29 (83)|
|Dec 2008 to Feb 2009||DRC||32||15 (47)|
|July 2012||Uganda||24||17 (71)|
|Nov 2012||DRC||77||36 (46)|
|Dec 2012||Uganda||7||4 (57)|
|2014 (as of October 17, 2014)||Guinea, Liberia, Sierra Leone, Nigeria, United States, Senegal, Spain (as of October 17, 2014)||8997 (as of October 17, 2014)||4493 (50) (as of October 17, 2014)|
|Data from Centers for Disease Control and Prevention and World Health Organization.|
|Year||Location||Proven * Cases Reported, No.|
|1989||Virginia, Texas, Pennsylvania||0|
|1990||Virginia and Texas||4|
|Data from Centers for Disease Control and Prevention and World Health Organization.
* Humans with serologic evidence of infection but without clinical disease.
† Associated with pig farming.[15, 16]