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Introduction

The virus Ebola causes a serious illness, known as hemorrhagic fever, in man and in non-human primates (monkeys, gorillas and chimpanzees).

Hemorrhagic fever is often fatal if not treated quickly. The virus, identified in 1976 in the Democratic Republic of Congo and Sudan, is transmitted by direct contact with blood, body fluids and tissues of infected people or animals. The incubation time of the disease varies between 2 and 21 days. Mortality, if the disease is not treated immediately, is very high with a death rate between 50 and 90%.

The rapid progression of the infection further complicates the management of the disease as it offers little chance for the human body to develop an adequate immune defense. Currently there is no specific antiviral therapy although a series of treatments such as blood products (blood derivatives), immune therapies and pharmacological therapies are being evaluated. The main treatment therefore consists in supporting the body in a general sense and reducing ailments (symptoms), with positive effects on survival. In November 2019, the European Medicines Agency authorized the first vaccine for the Ebola virus that meets the requirements of the World Health Organization for quality, safety and efficacy.

Symptoms

There Ebola virus disease, formerly known as Ebola virus hemorrhagic fever, is a serious infectious disease.The symptoms (symptoms) begin two days to three weeks after contracting the virus.

The main disorders that identify the infection appear abruptly and initially include:

  • fever
  • severe headache
  • sore throat
  • muscle and joint pain
  • chills
  • weakness

Over time, the symptoms (symptoms) become more and more severe and can include:

  • exhaustion
  • nausea and vomit
  • diarrhea
  • Red eyes
  • rash
  • renal and hepatic insufficiency
  • severe weight loss
  • bruises
  • internal or external bleeding with bleeding from the eyes
  • bleeding from the ears, nose and rectum, before death

Causes

The Ebola virus is an RNA (Ribonucleic Acid) virus belonging to the Filovirus family. It mainly affects man and primates (monkeys, gorillas and chimpanzees) but other animals are also carriers, such as pigs, antelopes and fruit bats. The genus of Filovirus also belongs to the family Marburgvirus And Cuevavirus.

Within the genus Ebolavirus six species have been identified:

  • Zaire (ZEBOV), associated with the highest mortality rate; this is the virus that caused the recent epidemic in the Democratic Republic of Congo (2018-2019) and the great epidemic in West Africa (2014-2016)
  • Sudan (SEBOV), located in Africa
  • Taї Forest (TAFV), located in Africa
  • Bundibugyo (BDBV), located in Africa
  • Reston (RESTV), located in the Philippines, is the only subtype that does not cause disease in humans but infects pigs and non-human primates (such as monkeys, gorillas and chimpanzees)
  • Bombali (BOMV), located in Africa

Ebola virus can be contracted through direct contact with the body fluids of animals (fruit bats, chimpanzees, gorillas, monkeys, antelopes or porcupines) or infected people.

According to the World Health Organization, the virus is introduced into the human population through the handling of an infected, sick or dead wild animal. Slaughtering or eating infected carcasses and coming into close contact with blood, secretions, organs or other body fluids of sick animals can help spread the virus.

People infected with the Ebola virus, on the other hand, typically become contagious when disorders (symptoms) appear. One can contract Ebola through direct contact with the mucous membranes, wounds or body fluids (blood, saliva, urine, feces, semen) of someone who is sick. Even objects, needles or dirty clothing contaminated with body fluids ( such as blood, feces, vomit) from a sick person or from the body of a person who died of Ebola can transmit the virus.

Family members are often infected while caring for sick relatives or preparing the dead for burial.
Medical personnel can become infected due to close contact with patients and insufficient use of protective equipment (surgical masks, gowns, latex gloves and goggles).

For most people, the risk of contracting Ebola is extremely low. However, it increases if you visit regions of Africa where the virus is present or epidemics have occurred in the past. Confirmed cases of the disease have been reported in the Democratic Republic of Congo, Sudan, Gabon, Uganda and Ivory Coast.

Diagnosis

The diagnosis (assessment) of the Ebola virus disease it is difficult in the initial stages of infection because the first ailments (symptoms) are similar to those of other infectious diseases, such as typhus and malaria. involved exposure to wild animals, are important to hypothesize the presence of the disease.

If suspected, doctors can use some laboratory tests to confirm the presence of the virus within a few days. Blood samples from infected people present an extreme biological risk and tests must be conducted on inactivated samples or only in conditions of maximum biological containment, i.e. maximum safety.

Diagnosis (ascertainment) of Ebola virus infection is made using several laboratory methods that detect:

  • antibodies directed against the virus (ELISA, Enzyme-Linked ImmunoSorbent Assay)
  • viral antigens
  • viral genome, by means of the RT-PCR technique (polymerase chain reaction with reverse transcription)
  • presence of the virus, by inoculating a small amount of blood into cell cultures

New tests have been developed to detect Ebola virus in saliva or urine samples and thus allow for a faster diagnosis (ascertainment) of the disease.

Therapy

There is no specific cure for Ebola virus disease. For this, the therapy consists of hospital treatment to relieve the ailments (symptoms):

  • oxygen
  • intravenous or oral fluids
  • blood transfusions
  • maintaining blood pressure within normal values
  • treatment of possible other infections
  • pain medications

New drug, immune or blood derivative (blood derivative) therapies are currently being evaluated. So far, however, no antiviral drug has been shown to be effective in treating Ebola infection. In November 2019, the European Medicines Agency authorized the first Ebola virus vaccine that meets the World Health Organization's requirements for quality. , safety and efficacy The vaccine has been shown to be effective in protecting people from the Ebola Zaire virus, the viral species associated with the highest mortality rate.

Prevention

For most people the risk of contracting the Ebola haemorrhagic fever it is extremely low. Even for the traveler who visits or works in areas where Ebola virus cases have occurred, the risk remains low. However, depending on the possibility of being exposed to the virus, the risk increases by doing the following activities:

  • management of sick people, in a family or health setting
  • preparation for the burial of deceased patients, with direct contact with their body
  • handling of infected animals, dead or alive. For example, monkeys, gorillas, chimpanzees (primates), forest antelopes, pigs, porcupines, or fruit bats

In order to avoid Ebola virus infection, it is useful to reduce or avoid contact with wild animals, not to touch raw meat of animals that may be infected (mainly fruit bats and primates) and to cook it before eating. To reduce the risk of human-to-human transmission close physical contact or close contact with infected persons should be avoided Gloves and adequate personal protective equipment should be worn when visiting patients in hospital.

Complications

Ebola virus disease can cause serious consequences which include:

  • multiple organ failure (liver damage, kidney failure etc.)
  • gastrointestinal bleeding
  • blood clotting within blood vessels (intravascular)
  • yellow coloring of the eyes and mucous membranes (jaundice)
  • loss of consciousness
  • coma
  • shock from decrease in the amount of blood circulating (hypovolemic shock), a condition that occurs when the amount of blood in the blood vessels is one-fifth of normal

In people who survive, recovery is slow and can be accompanied by various medical problems, even after passing the acute phase. Complications of the disease that can appear in convalescence include:

  • hair loss
  • hepatitis
  • weakness
  • headache
  • eye inflammation
  • central nervous system disorders

Living with

The Ebola virus is one of the most aggressive viruses known to science, fatal in about 50-90% of cases. Survival appears to depend on the viral strain and the initial response to infection by the body's defense system (immune response). However, it is not yet known why some people survive while others do not, nor the specific mechanisms. which make the Ebola virus capable of causing such an aggressive disease.

Bibliography

World Health Organization (WHO). Ebola Virus Disease. Fact sheet 103 (Translation by the Ministry of Health - Directorate General for Prevention)

In-depth link

EpiCentro (ISS). Ebola virus disease

World Health Organization (WHO). Ebola virus disease (English)

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