Ebola Virus Disease (EVD) Information for Clinicians in U.S. Healthcare Settings

Key Points

  1. EVD can be confused with other more common infectious diseases such as malaria, typhoid fever, meningococcemia, and other bacterial infections. Follow CDC’s PPE guidance for confirmed Ebola patients.
  2. Gastrointestinal symptoms may develop after about 5 days to develop symptoms such as severe watery diarrhea, nausea, vomiting, and abdominal pain.
  3. Ebola virus enters the patient through mucous membranes, breaks in the skin, or parenterally. Healthcare personnel must prevent direct contact or splashes with blood and body fluids, contaminated equipment, and soiled environmental surfaces.
  4. Travelers with possible exposure to Ebola virus may need public health monitoring and movement controls depending on the risk of exposure and clinical presentation. Clinicians should contact local or state health departments for more information.

Clinical Presentation and Course

Patients with EVD generally have abrupt onset of fever and symptoms typically 8 to12 days after exposure (incubation period for current outbreak has a mean of approximately 9 to 11 days). Initial signs and symptoms are nonspecific and may include elevated body temperature or subjective fever, chills, myalgias, and malaise. Because of these nonspecific symptoms, particularly early in the course of the disease, EVD often can be confused with other more common infectious diseases such as malaria, typhoid fever, meningococcemia, and other bacterial infections (for example, pneumonia).

Patients can progress from the initial nonspecific symptoms after about 5 days to develop gastrointestinal symptoms such as severe watery diarrhea, nausea, vomiting, and abdominal pain. Other symptoms such as chest pain, shortness of breath, headache, or confusion also may develop. Patients often have conjunctival injection. Hiccups have been reported. Seizures may occur, and cerebral edema has been reported. Bleeding is not universally present but can manifest later in the course as petechiae, ecchymosis/bruising, or oozing from venipuncture sites and mucosal hemorrhage. Frank hemorrhage is less common. In the current outbreak unexplained bleeding has been reported in only 18% of patients, most often blood in the stool (about 6%). Patients may develop a diffuse erythematous maculopapular rash by day 5 to 7 (usually involving the neck, trunk, and arms) that can desquamate. Pregnant women may experience spontaneous miscarriages. The most common signs and symptoms reported from West Africa during the current outbreak from symptom-onset to the time the case was detected include: fever (87%), fatigue (76%), vomiting (68%), diarrhea (66%), and loss of appetite (65%).

Patients with fatal disease usually develop more severe clinical signs early during infection and die typically between days 6 and 16 of complications including multiorgan failure and septic shock (mean of 7.5 days from symptom onset to death during the 2014-2016 outbreak in West Africa). In nonfatal cases, patients may have fever for several days and improve, typically around day 6. Patients who survive can have a prolonged convalescence.

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Pathogenesis

Ebola virus enters the patient through mucous membranes, breaks in the skin, or parenterally and infects many cell types, including monocytes, macrophages, dendritic cells, endothelial cells, fibroblasts, hepatocytes, adrenal cortical cells, and epithelial cells. The incubation period may be related to the infection route (6 days for injection versus 10 days for contact). Ebola virus migrates from the initial infection site to regional lymph nodes and subsequently to the liver, spleen, and adrenal gland. Although not infected by Ebola virus, lymphocytes undergo apoptosis resulting in decreased lymphocyte counts. Hepatocellular necrosis occurs and is associated with dysregulation of clotting factors and subsequent coagulopathy. Adrenocortical necrosis also can be found and is associated with hypotension and impaired steroid synthesis. Ebola virus appears to trigger a release of pro-inflammatory cytokines with subsequent vascular leak and impairment of clotting ultimately resulting in multiorgan failure and shock.

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Laboratory Findings

Laboratory findings at admission may include leukopenia frequently with lymphopenia followed later by elevated neutrophils and a left shift. Platelet counts often are decreased in the 50,000 to 100,000 range. Amylase may be elevated, reflecting pancreatic involvement (inflammation/infection). Hepatic transaminases are elevated with aspartate aminotransferase (AST) exceeding alanine aminotransferase (ALT); these values may peak at more than 1,000 IU/L. Proteinuria may be present. Prothrombin (PT) and partial thromboplastin times (PTT) are prolonged and fibrin degradation products are elevated, consistent with disseminated intravascular coagulation (DIC).

For more information on laboratory testing, please see our Laboratory Testing website.

 

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Treatment

Clinical management of EVD should focus on supportive care of complications, such as hypovolemia, electrolyte abnormalities, hematologic abnormalities, refractory shock, hypoxia, hemorrhage, septic shock, multiorgan failure, and DIC.

Recommended care includes volume repletion, maintenance of blood pressure (with vasopressors if needed), and maintenance of oxygenation, pain control, nutritional support, and treatment of  secondary bacterial infections and pre-existing comorbidities. Large volumes of intravenous fluids are often required to correct dehydration due to diarrhea and vomiting. Some patients may develop profound third-spacing of fluids due to vascular leak. Some organizations suggest the addition of broad-spectrum antimicrobials, particularly in patients with evidence of septic shock. Infection prevention and control measures are a critical part of clinical management. Consider all bodily fluids and clinical specimens as potentially infectious.

Investigational Treatment

The US Food and Drug Administration (FDA) has not yet approved a specific treatment for Ebola virus infection. Several investigational treatments have been evaluated in clinical trials. These trials show patients receiving REGN-EB3 and mAb114 had a greater chance of survival compared to patients receiving other treatments under investigation. The overall survival for those receiving either mAb114 or REGN-EB3 was approximately 70% and for those presenting with a low viral load it was approximately 90%.

REGN-EB3 is a three monoclonal antibody combination/cocktail intended for use in all patients. mAb114 is a monoclonal antibody molecule that flags the Ebola virus (Zaire ebolavirus) for action by the immune system. mAb114 is intended for use in infected adults and children who are at early stages of infection symptoms.

For more information on Ebola Treatment, visit the WHO’s Ebola Treatment and Careexternal icon website.

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Vaccine

The U.S. Food and Drug Administration (FDA) approved the Ebola vaccine rVSV-ZEBOV (tradename “Ervebo”) on December 19, 2019. The rVSV-ZEBOV vaccine is a single dose vaccine regimen that has been found to be safe and protective against only the Zaire ebolavirus species of ebolavirus. This is the first FDA approval of a vaccine for Ebola.

Adverse effects following vaccination can occur. While typically mild, reported adverse effects include headache, fatigue, muscle pain, and mild fever. It is not possible to get Ebola from the rVSV-ZEBOV vaccine because it does not contain the whole Ebola virus. The vaccine contains only a small piece from the Ebola virus (species Zaire ebolavirus) that helps the body build defenses against Ebola infection. Only the whole Ebola virus can cause an infection.

After receiving the vaccine, it is important to continue infection prevention precautions against Ebola (for example, wear PPE that covers clothing and skin and prevents any exposure of the eyes, nose, and mouth; wash hands; avoid contact with blood and body fluids) because the vaccine may not be 100% effective for everyone.

 

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