Ebola fever

Ebola outbreak in Gulu Municipal Hospital

Ebola virus disease (EVD) is a deadly disease with occasional outbreaks that occur mostly on the African continent. EVD most commonly affects people and nonhuman primates (such as monkeys, gorillas, and chimpanzees). It is caused by an infection with a group of viruses within the genus Ebolavirus:

• Ebola virus (species Zaire ebolavirus)
• Sudan virus (species Sudan ebolavirus)
• Taï Forest virus (species Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus)
• Bundibugyo virus (species Bundibugyo ebolavirus)
• Reston virus (species Reston ebolavirus)
• Bombali virus (species Bombali ebolavirus)

Of these, only four (Ebola, Sudan, Taï Forest, and Bundibugyo viruses) have caused disease in people. Reston virus can cause disease in nonhuman primates and pigs, but there have not been cases in people. Bombali virus was first identified in bats in 2018, and experts do not know yet if it causes disease in either animals or people.

History of Ebola

Ebola virus disease (EVD), one of the deadliest viral diseases, was discovered in 1976 when two consecutive outbreaks of fatal hemorrhagic fever occurred in different parts of Central Africa. The first outbreak occurred in the Democratic Republic of Congo (formerly Zaire) in a village near the Ebola River, which gave the virus its name. The second outbreak occurred in what is now South Sudan, approximately 500 miles (850 km) away.

2014 ebola virus epidemic in West Africa CS

Initially, public health officials assumed these outbreaks were a single event associated with an infected person who traveled between the two locations. However, scientists later discovered that the two outbreaks were caused by two genetically distinct viruses: Zaire ebolavirus and Sudan ebolavirus. After this discovery, scientists concluded that the virus came from two different sources and spread independently to people in each of the affected areas.

Viral and epidemiologic data suggest that Ebola virus existed long before these recorded outbreaks occurred.  Factors like population growth, encroachment into forested areas, and direct interaction with wildlife (such as bushmeat consumption) may have contributed to the spread of the Ebola virus.

Since its discovery in 1976, the majority of cases and outbreaks of Ebola Virus Disease have occurred in Africa. The 2014-2016 Ebola outbreak in West Africa began in a rural setting of southeastern Guinea, spread to urban areas and across borders within weeks, and became a global epidemic within months.

Transmission

Scientists think people are initially infected with Ebola virus through contact with an infected animal, such as a fruit bat or nonhuman primate. This is called a spillover event. After that, the virus spreads from person to person, potentially affecting a large number of people.

The virus spreads through direct contact (such as through broken skin or mucous membranes in the eyes, nose, or mouth) with:

• Blood or body fluids (urine, saliva, sweat, feces, vomit, breast milk, amniotic fluid, and semen) of a person who is sick with or has died from Ebola virus disease (EVD).
• Objects (such as clothes, bedding, needles, and medical equipment) contaminated with body fluids from a person who is sick with or has died from EVD.
• Infected fruit bats or nonhuman primates (such as apes and monkeys).
• Semen from a man who recovered from EVD (through oral, vaginal, or anal sex). The virus can remain in certain body fluids (including semen) of a patient who has recovered from EVD, even if they no longer have symptoms of severe illness. There is no evidence that Ebola can be spread through sex or other contact with vaginal fluids from a woman who has had Ebola.

When people become infected with Ebola, they do not start developing signs or symptoms right away. This period between exposure to an illness and having symptoms is known as the incubation period. A person can only spread Ebola to other people after they develop signs and symptoms of Ebola.

Additionally, Ebola virus is not known to be transmitted through food. However, in certain parts of the world, Ebola virus may spread through the handling and consumption of wild animal meat or hunted wild animals infected with Ebola. There is no evidence that mosquitoes or other insects can transmit Ebola virus.

Risk factors

Health workers who do not use proper infection control while caring for Ebola patients, and family and friends in close contact with Ebola patients, are at the highest risk of getting sick. Ebola can spread when people come into contact with infected blood or body fluids. Ebola poses little risk to travelers or the general public who have not cared for or been in close contact (within 3 feet or 1 meter) with someone sick with Ebola.

Signs and Symptoms

Symptoms of ebola

Symptoms may appear anywhere from 2 to 21 days after contact with the virus, with an average of 8 to 10 days. The course of the illness typically progresses from “dry” symptoms initially (such as fever, aches and pains, and fatigue), and then progresses to “wet” symptoms (such as diarrhea and vomiting) as the person becomes sicker. Primary signs and symptoms of Ebola often include some or several of the following:

• Fever
• Aches and pains, such as severe headache and muscle and joint pain
• Weakness and fatigue
• Sore throat
• Loss of appetite
• Gastrointestinal symptoms including abdominal pain, diarrhea, and vomiting
• Unexplained hemorrhaging, bleeding or bruising
• Other symptoms may include red eyes, skin rash, and hiccups (late-stage).

Many common illnesses can have the same symptoms as EVD, including influenza (flu), malaria, or typhoid fever.

EVD is a rare but severe and often deadly disease. Recovery from EVD depends on good supportive clinical care and the patient’s immune response. Studies show that survivors of Ebola virus infection have antibodies (proteins made by the immune system that identify and neutralize invading viruses) that can be detected in the blood up to 10 years after recovery. Survivors are thought to have some protective immunity to the type of Ebola that sickened them.

Diagnosis

If a person shows signs of EVD and has had a possible exposure, he or she should be isolated (separated from other people) and public health authorities notified. Blood samples from the patient should be collected and tested to confirm infection. Ebola virus can be detected in blood after onset of symptoms. It may take up to three days after symptoms start for the virus to reach detectable levels.

Polymerase chain reaction (PCR) is one of the most commonly used diagnostic methods because of its ability to detect low levels of Ebola virus. PCR methods can detect the presence of a few virus particles in small amounts of blood, but the ability to detect the virus increases as the amount of virus increases during an active infection. When the virus is no longer present in great enough numbers in a patient’s blood, PCR methods will no longer be effective. Other methods, based on the detection of antibodies an EVD case produces to an infection, can then be used to confirm a patient’s exposure and infection by Ebola virus.

A positive laboratory test means that Ebola infection is confirmed. Public health authorities will conduct a public health investigation, including identifying and monitoring all possibly exposed contacts.

Treatment

Therapeutics

There are currently two treatments* approved by the U.S. Food and Drug Administration (FDA) to treat EVD caused by the Ebola virus, species Zaire ebolavirus, in adults and children. The first drug approved in October 2020, Inmazeb™external icon, is a combination of three monoclonal antibodies. The second drug, Ebanga™external icon, is a single monoclonal antibody and was approved in December 2020. Monoclonal antibodies (often abbreviated as mAbs) are proteins produced in a lab or other manufacturing facility that act like natural antibodies to stop a germ such as a virus from replicating after it has infected a person. These particular mAbs bind to a portion of the Ebola virus’s surface called the glycoprotein, which prevents the virus from entering a person’s cells.

Both of these treatments, along with two others, were evaluated in a randomized controlled trial during the 2018-2020 Ebola outbreak in the Democratic Republic of the Congo. Overall survival was much higher for patients receiving either of the two treatments that are now approved by the FDA. Neither Inmazeb™ nor Ebanga™ have been evaluated for efficacy against species other than Zaire ebolavirus.

Supportive Care

• Whether or not other treatments are available, basic interventions can significantly improve chances of survival when provided early. These are referred to as supportive care, and include:
• Providing fluids and electrolytes (body salts) orally or through infusion into the vein (intravenously).
• Using medication to support blood pressure, reduce vomiting and diarrhea, and to manage fever and pain.
• Treating other infections, if they occur.

Prevention

When living in or traveling to a region where Ebola virus is potentially present, there are a number of ways to protect yourself and prevent the spread of EVD.

• Avoid contact with blood and body fluids (such as urine, feces, saliva, sweat, vomit, breast milk, amniotic fluid, semen, and vaginal fluids) of people who are sick.
• Avoid contact with semen from a man who has recovered from EVD, until testing shows that the virus is gone from his semen.
• Avoid contact with items that may have come in contact with an infected person’s blood or body fluids (such as clothes, bedding, needles, and medical equipment).
• Avoid funeral or burial practices that involve touching the body of someone who died from EVD or suspect EVD.
• Avoid contact with bats, forest antelopes, and nonhuman primates (such as monkeys and chimpanzees) blood, fluids, or raw meat prepared from these or unknown animals (bushmeat).

Ebola Vaccine

The U.S. Food and Drug Administration (FDA) approved the Ebola vaccine rVSV-ZEBOV (called Ervebo®) on December 19, 2019. This is the first FDA-approved vaccine for Ebola.

This vaccine is given as a single dose vaccine and has been found to be safe and protective against Zaire ebolavirus, which has caused the largest and most deadly Ebola outbreaks to date.

On February 26, 2020, the Advisory Committee on Immunization Practices (ACIP) recommended pre-exposure prophylaxis vaccination with rVSV-ZEBOV for adults ≥ 18 years of age in the U.S. population who are at potential occupational risk of exposure to Zaire ebolavirus.

Ebola fever Resources
Latest articles Most recent articles Ongoing trials	Wikipedia

Classification	ICD-10: A98.4 MeSH: D019142 DiseasesDB: 18043
External resources	MedlinePlus: 001339 eMedicine: med/626

Ebola fever Resources
Latest articles Most recent articles Ongoing trials	Wikipedia