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Ebola Virus Disease


Ebola is one of several viruses that can cause Viral Hemorrhagic Fever.  The first Ebolavirus species was discovered in 1976 in what is now the Democratic Republic of the Congo, near the Ebola River. Since then, outbreaks have occurred sporadically, mainly in West and Central Africa.  Ebola Virus Disease (EVD) has a high mortality rate and there is no treatment proven to be effective, although experimental treatment for EVD is undergoing evaluation.  


2014 Ebola Virus Disease in West Africa and the USA 

The largest known outbreak of Ebola Virus Disease has been underway since early 2014 in multiple countries in West Africa.  An imported case from Liberia and healthcare-associated cases have occurred in the USA.  For comprehensive, updated information on Ebola disease, outbreak locations, case counts, and detailed guidance for healthcare professionals and the public, please see the CDC page on the 2014 Ebola West Africa Outbreak.



The natural reservoir host for Ebola virus is believed to be bats. The way in which outbreaks in humans begin is not certain, but researchers believe that the first patient becomes infected through contact with an infected animal.  Humans can then transmit the infection to other humans, by direct contact through broken skin or mucous membranes with a sick person's blood or body fluids (urine, saliva, feces, vomit, and semen) or with objects (such as needles) that have been contaminated with infected body fluids.  Humans with Ebola become infectious once they begin to have symptoms.  Healthcare workers and the family and friends in close contact with Ebola patients are at the highest risk of getting sick because they may come in contact with infected blood or body fluids.



Symptoms of Ebola Virus Disease (EVD) may appear anywhere from 2 to 21 days after exposure to Ebola virus, although 8-10 days is most common.  Symptoms of Ebola typically include:  fever (greater than 38.6°C or 101.5°F), severe headache, muscle pain, weakness, diarrhea, vomiting, abdominal (stomach) pain, lack of appetite. Patients may also experience:  rash, red eyes, hiccups, cough, sore throat, chest pain, difficulty breathing or swallowing, and unexplained bleeding inside and outside the body.



Diagnosing Ebola may be challenging because the early symptoms, such as fever, red eyes and a skin rash, are not specific to Ebola infection and are seen often in patients with more commonly occurring diseases. CDC has published EVD case definitions as well as guidance on Ebola specimen collection and testing. San Francisco clinicians should immediately contact SFDPH Communicable Disease Control regarding any suspected cases, and/or to arrange for testing.



There is as yet no vaccine available to prevent Ebola infection.  The aim of all prevention techniques is to avoid contact with the blood or body fluids of infected persons.  This includes avoiding travel to areas where Ebola outbreaks are occurring, and taking precautions when providing health care for potentially infectious persons.  Precautions may include wearing of protective clothing (such as masks, gloves, gowns, and goggles), using infection-control measures (such as complete equipment sterilization and routine use of disinfectant), and isolating patients with Ebola from contact with unprotected persons.  See CDC guidance on infection control in healthcare settings.  


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