Understanding the Ebola Virus
Previous Ebola outbreaks have seen fatality rates as high as 90%. The current epidemic, primarily across Guinea, Sierra Leone, and Liberia, has seen 729 deaths out of more than 1353 confirmed infections, which equals about a 53% mortality rate to date.
Ebola virus is a member of the Filoviridae family. First isolated in 1976, 5 subtypes of Ebola virus are now recognized, of which 4 are pathogenic to humans. The Reston subtype infects only primates. The most deadly form is the Zaire subtype, with the natural reservoir for the virus believed to be the fruit bat. The virus has also been found in porcupines, primates, and wild antelope.
Ebola virus incubates in infected humans for 2-21 days, with the majority of patients becoming symptomatic after 8-9 days. Once infected, patients can experience severe symptoms within 1-2 days.
Symptoms of Ebola include:
• Sudden fever, often as high as 103º-105º F;
• Intense weakness, sore throat, and headache; and
• Profuse vomiting and diarrhea (occurs 1-2 days after the aforementioned symptoms).
More severe symptoms, such as the development of coagulopathy with thrombocytopenia, can develop in as soon as 24-48 hours, leading to bleeding from the nasal or oral cavities, along with hemorrhagic skin blisters. The development of renal failure, leading to multisystem organ failure along with disseminated intravascular coagulation, can then rapidly ensue over 3-5 days, along with significant volume loss.
Patients who develop a fulminant course often die within 8-9 days. Those who survive beyond 2 weeks have a better prognosis for survival.
The Difficulties of Ebola Diagnoses
One of the difficulties encountered in identifying Ebola virus is that in the early days of the disease, the symptoms may be similar to those of other types of infectious diseases, such as malaria, Lassa fever, typhoid, cholera, and even meningitis. Only after 3-5 days (or even later in the course of the disease) might the hemorrhagic blisters -- along with internal hemorrhage, the hallmark of the illness -- become evident.
Ebola, because it is not airborne or spread by droplets, is not nearly as contagious as measles or influenza. Patients with measles or influenza can spread the virus before they are symptomatic, as opposed to those with Ebola, who are not infectious until symptoms have developed. Furthermore, direct contact with infected secretions, such as saliva, is essential to transmitting the Ebola virus. You cannot acquire Ebola virus if another person coughs or sneezes close to you, and it is not spread by casual contact. Rather, it is acquired by direct contact with infected secretions such as vomit, diarrhea, and blood primarily. It may also be spread by direct contact with saliva, sweat, and tears. Other means of transmission include contact of secretions with a skin opening or healing wound, or if a person contacts secretions and touches his or her eyes, nose, or mouth.
It is important to remember that only patients who are symptomatic are contagious and can then transmit the virus to others through their secretions. Those who have contracted the disease are primarily healthcare workers caring for patients, as well as family members who have had close contact with infected patients. Another method of infection has involved family members who handle corpses at the time of burial, along with those who eat fruit bats, antelope, or other animals potentially infected with the virus.
Studies indicate that the virus is in much higher concentration in vomit, blood, and diarrhea compared with saliva, sweat, and tears, making disinfection of public areas such as restrooms imperative in order to contain the virus.
The actual risk to citizens living and working in the United States is quite low, and the public should be well aware that emergency departments (EDs) and critical care units in the United States are well equipped and prepared in the event that a patient with a recent travel history from West Africa, along with flu-like and gastrointestinal symptoms, presents to the hospital.
As the ED is often the proverbial "front door" to the hospital, universal precautions, along with a protocol to quarantine and isolate such patients, is now a top priority for all EDs. Such a plan requires healthcare providers to wear personal protective equipment, including eyewear or goggles, facemask, gloves, and a gown.
Effective decontamination methods for the virus include steam sterilization, chemical sterilization, incineration, and gaseous methods.
Medscape Emergency Medicine © 2014
Cite this article: Robert D. Glatter. Ebola: What US Clinicians Need to Know - Medscape - Aug 04, 2014.