ebola virus disease (evd) جمع آوری توسط : دکتر احمد رضا مبیّن متخصص...

Ebola virus disease (EVD)

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دکتر احمد رضا مبّی�نمتخصص بّیماریهای عفونی

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Ebola was first discovered in 1976 near the Ebola River in what is now the Democratic Republic of the Congo. Since then,

outbreaks of Ebola among humans have appeared sporadically in Africa

Number of new cases of Ebola virus disease reported — Guinea, Liberia, and Sierra Leone, November 9–30, 2014

• Definition▫Ebola hemorrhagic fever are severe and often

fatal diseases characterized by: High fever, headache, malaise, myalgia, coagulation disorders, multiorgan failure sore throat, Vomiting in particular, the appearance of a maculopapular

rash Stomach pain Lack of appetite

As the virus spreads through the body, it damages the immune system and organs. Ultimately, it causes levels of blood-clotting cells to drop. This leads to severe, uncontrollable bleeding

As the disease gets worse, it causes bleeding inside the body, as well as from the eyes, ears, and nose. 

Some people will vomit or cough up blood, have bloody diarrhea, and get a rash

Signs and Symptoms• Fever (greater than 38.6°C or 101.5°F)• Severe headache• Muscle pain• Weakness• Diarrhea• Vomiting• Abdominal (stomach) pain• Unexplained hemorrhage (bleeding or bruising)

Symptoms may appear anywhere from 2 to 21 days after exposure to Ebola, but the average is 8 to 10 days.

Recovery from Ebola depends on the patient’s immune response. People who recover from Ebola infection develop antibodies that last for at least 10 years.

Epidemiology•Human outbreaks occur sporadically in regions of

Central Africa.•Recent evidence suggests that bats may play a role as

a reservoir host.•The manner in which filovirus outbreaks are initiated

is unknown; however, it is thought that the initial cases occur as a result of contact with an infected animal.

•Nosocomial transmission has occurred frequently during outbreaks of filovirus hemorrhagic fever in endemic areas.

Distribution of cases of EVD, by week of reporting: Guinea, Sierra Leone, Liberia, Nigeria, Senegal and Mali, weeks 48/2013 to 5/2015, as of 27 January 2015

Districts Affected by Ebola Virus Disease in Three Countries in AfricaGuinea, Liberia, and Sierra Leone

Medical evacuations and repatriations from EVD-affected and previously affected countries, as of 28 January 2015

Transmission• When an infection does occur in humans, the virus

can be spread in several ways to others. Ebola is spread through direct contact (through broken skin or mucous membranes) with▫ blood or body fluids (including but not limited to

urine, saliva, feces, vomit, and semen) of a person who is sick with Ebola

▫ objects (like needles and syringes) that have been contaminated with the virus

▫ infected animals ▫ Ebola is not spread through the air or by water, or

in general, food. However, in Africa, Ebola may be spread as a result of handling bush meat (wild animals hunted for food) and contact with infected bats.

Notice

• During outbreaks of Ebola, the disease can spread quickly within healthcare settings (such as a clinic or hospital).

• Exposure to Ebola can occur in healthcare settings where hospital staff are not wearing appropriate protective equipment, including masks, gowns, and gloves and eye protection

• If instruments are not disposable, they must be sterilized before being used again

Risk of Exposure

• All cases of human illness or death from Ebola have occurred in Africa (with the exception of several laboratory contamination cases)

• Healthcare providers caring for Ebola patients and the family and friends in close contact with Ebola patients are at the highest risk of getting sick

• People also can become sick with Ebola after coming in contact with infected wildlife

Outbreaks• Past Ebola outbreaks have occurred in the following

countries:▫ Democratic Republic of the Congo (DRC)▫ Gabon▫ South Sudan▫ Ivory Coast▫ Uganda▫ Republic of the Congo (ROC)▫ South Africa (imported)

• Current Ebola Outbreak in West Africa The 2014 Ebola outbreak is the largest Ebola outbreak in history and the first in West Africa. The current outbreak is affecting multiple countries in West Africa

Laboratory tests used in diagnosis

Timeline of Infection Diagnostic tests availableWithin a few days after symptoms begin

Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing

IgM ELISA

Polymerase chain reaction (PCR)

Virus isolation

Later in disease course or after recovery

IgM and IgG antibodies

Retrospectively in deceased patients

Immunohistochemistry testing

PCR

Virus isolation

Treatment• No specific vaccine or medicine (e.g., antiviral drug) has

been proven to be effective against Ebola.• Symptoms of Ebola are treated as they appear. The

following basic interventions, when used early, can significantly improve the chances of survival:▫ Providing intravenous fluids (IV) and balancing electrolytes (body

salts)▫ Maintaining oxygen status and blood pressure▫ Treating other infections if they occur

1. Some experimental treatments developed for Ebola have been tested and proven effective in animals but have not yet been tested in randomized trials in humans.

2. Recovery from Ebola depends on the patient’s immune response. People who recover from Ebola infection develop antibodies that last for at least 10 years, possibly longer

3. kills up to 50-90% of people who are infected

Ebola antiviral development• A number of candidate antiviral treatments have

shown promise in non-human primate models. Several potential drugs have been used in experimental treatments of individual EVD cases, e.g.

▫brincidofovir (Chimerix, USA), ▫favipiravir (Toyama Chemicals, Japan and

MediVector Inc., USA), ▫TKM-Ebola (Tekmira pharmaceutical

Corporation, Canada) ▫ZMapp (Mapp Biopharmaceutical Inc., USA)

Ebola vaccines development

Three vaccine candidates in advanced stages of development are being studied in clinical trials focusing on healthy adults:

Prevention

•There are no approved vaccines against Ebola viruses.

•Barrier nursing procedures include wearing protective clothing, masks, and eye shields.

•Isolation of infected patients and close contacts is essential.

•Avoid contact with bush meat and sick animals, particularly nonhuman primates, in endemic regions.

•Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a severe, often fatal illness in humans.

•The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission.

•The average EVD case fatality rate is around 50%. Case fatality rates have varied from 25% to 90% in past outbreaks.

•The first EVD outbreaks occurred in remote villages in Central Africa, near tropical rainforests, but the most recent outbreak in west Africa has involved major urban as well as rural areas.

•Community engagement is key to successfully controlling outbreaks. Good outbreak control relies on applying a package of interventions, namely:

case management, surveillance and contact tracing, a good laboratory service, safe burials social mobilisation.

•Three core interventions have stopped every previous Ebola outbreak and can stop this one as well: ▫exhaustive case and contact finding, ▫effective response to patients and the

community, ▫preventive interventions.

Nejm.org september 25, 2014 Thomas R. Frieden, M.D., M.P.H

Local time on August 2 , two American patients return home the day

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