THE EBOLA VIRUS CRAZE: The Facts
The disease caused by the Ebola virus in humans is similar in its clinical manifestations, differing only in severity and case-fatality rate. Of note, despite the traditional name of Ebola hemorrhagic fever, bleeding is not a common finding, and is typically seen only in the terminal phase of illness. In the West Africa epidemic the term Ebola virus disease has been used rather than the name Ebola hemorrhagic fever.
Incubation period — Patients with Ebola virus disease typically have an abrupt onset of symptoms 8 to 12 days after exposure. There is no evidence that asymptomatic persons still in the incubation period are infectious to others. However, all symptomatic individuals should be assumed to have high levels of virus in the blood and other body fluids and appropriate safety precautions should be taken.
Symptoms and signs — Patients with Ebola virus disease initially present with non-specific influenza-like symptoms and can progress to multi-organ failure and septic shock. The most common signs and symptoms reported from West Africa during the 2014 outbreak include: fever (87 percent), fatigue (76 percent), vomiting (68 percent), diarrhea (66 percent), and loss of appetite (65 percent).
Important clinical findings of patients with Ebola virus disease are as follows:
- Nonspecific flu-like symptoms — Ebola typically begins with the abrupt onset of fever, chills, and general malaise. Other signs and symptoms include weakness, anorexia, severe headache, and pain in the muscles of the trunk and lower back. A nonproductive cough and pharyngitis, with the sensation of a lump or “ball” in the throat, are also frequently present.
- Rash — Some patients develop a diffuse erythematous, nonpruritic maculopapular rash by day five to seven of illness. The rash usually involves the face, neck, trunk, and arms.
- Gastrointestinal — Gastrointestinal signs and symptoms usually develop several days after the initial presentation. These include watery diarrhea, nausea, vomiting, and abdominal pain.
- Hemorrhage — Bleeding is often not observed in the early phase of illness, but may manifest later in the course of disease as petechiae, ecchymosis/bruising, oozing from venipuncture sites, and/or mucosal hemorrhage. Frank hemorrhage is seen most commonly in the terminal phase of illness. During the outbreak in West Africa, approximately 20 percent of patients had unexplained bleeding, which is most commonly manifested as blood in the stool (about 6 percent).
- Other findings — Patients with Ebola virus disease can present with additional findings such as hiccups, chest pain, shortness of breath, headache, confusion, seizures, and/or cerebral edema. Conjunctival injection and dark red discoloration of the soft palate are common physical findings. Pregnant women may experience spontaneous miscarriages.
In non-fatal cases, patients typically improve approximately 6 days after the onset of symptoms. The formation of antigen-antibody complexes during recovery may cause acute arthralgias and other symptoms.
Fatal disease has been characterized by more severe clinical signs early during infection and progression to multiorgan failure and septic shock. Death typically occurs between days 6 and 16.
Prognostic factors — Certain clinical and laboratory findings may be able to inform prognosis.
Patients who have evidence of severe dehydration, metabolic abnormalities, and impaired oxygen delivery are most likely to have a poor outcome. Signs and symptoms that are manifestations of these abnormalities include fast breathing, minimal urine, delirium, coma, and irreversible shock. In addition, patients with persistently high or increasing Ebola virus RNA levels in the bloodstream are likely to die.
Patients who survive infection with Ebola virus typically show signs of clinical improvement during the second week of illness. In these patients, viremia also resolves during the second week, in association with the appearance of virus-specific antibodies.
SUMMARY AND RECOMMENDATIONS:
- The largest outbreak of Ebola virus disease is the West African outbreak caused by the Zaire species of the virus. This outbreak started in the West African nation of Guinea in late 2013 and was confirmed by the World Health Organization in March 2014. The countries with widespread transmission include Guinea, Liberia, and Sierra Leone. Cases of Ebola virus disease related to this outbreak have also been reported outside of West Africa (eg, Spain and United States). These cases have occurred in healthcare workers caring for patients with Ebola virus disease, as well as a returning traveler.
- Person-to-person transmission requires direct contact with blood or other virus-containing body fluids. It is not transmitted through the air, and therefore is not an airborne virus.
- The incubation period is typically 8 to 12 days, but can range from 2 to 21 days.
- Patients with the Ebola virus disease usually have an abrupt onset of non-specific symptoms, such as fever, malaise, and myalgias. As the illness progresses, patients develop worsening prostration, stupor, and hypotension.
- Ebola virus can persist for some time in certain bodily fluids, such as semen and breast milk. In one known instance, viral persistence in semen led to virus transmission through sexual contact.