Ebola Virus Disease (EVD) Symptoms and Causes

Ebola virus disease (EVD, formerly known as Ebola virus hemorrhagic fever ) is an acute viral infection caused by the Ebola virus (EBOV) of filoviridae . The Ebola virus is one of the most ferocious diseases in the world with a mortality rate of 90%. It has caused many outbreaks of scale . It is mainly transmitted by contact with blood , body fluids and tissues of infected animals or humans . Patients with severe illness require critical supportive care. During the epidemic, health workers, family members, and others who have close contact with patients or the deceased face a higher risk of infection. The main pathological changes in the disease are involvement of the mononuclear phagocytic system, thrombosis and hemorrhage. Extensive necrosis of the whole body, especially in the liver, spleen, kidney, and lymphoid tissues.

Ebola virus

Ebola virus (EBOV) is also translated as Ebola virus , a very rare virus, in 1976 in southern Sudan and Zaire, now Congo (Golden) Ebo After discovering its existence in the Lahe area, it attracted widespread attention and attention from the medical community. Ebola was named after it.

The shape of the “Ebola” virus is like the “Ruyi” of ancient China . The study of members of the Ebola virus using electron microscopy shows that it exhibits a linear structure of general fibrosis. Ebola virus is a single strand of negative strand RNA.

The Ebola virus genus is one of the three members of the filamentous virus family ( linear virus ), and the other two are the Marburg virus genus and the Cuevavirus genus. The Ebola virus genus consists of five different genera:

  1. Benedictine Ebola Virus (BDBV)
  2. Zaire Ebola Virus (EBOV)
  3. Reston Ebola Virus (RESTV)
  4. Sultan Ebola Virus (SUDV)
  5. Tay Forest Ebola virus]] (TAFV).

The Benedictine Ebola virus, the Zaire Ebola virus and the Sudan Ebola virus are associated with a large outbreak of Ebola virus disease in Africa, while the Reston Ebola virus and the Tay forest Ebola virus Nothing to do with it. The Reston Ebola virus species are found in the Philippines and the People’s Republic of China and can infect humans, but so far the incidence or death of this species has not been reported in humans.


Ebola is transmitted to humans by intimate contact with the blood , secretions, organs or other body fluids of infected animals . In Africa, it has been documented that it is afflicted by dealing with infected diseases found in tropical rainforests or by killing chimpanzees, gorillas, fruit bats, monkeys, forest antelopes and porcupines.

Ebola is then spread in human society through interpersonal transmission, which is in direct contact with the blood, secretions, organs or other body fluids of infected people (through damaged skin or mucous membranes ), and indirect contact with such body fluids. Caused by the environment. In the burial ceremony, the mourners have direct contact with the bodies of the deceased, which may also have an effect on the spread of Ebola. Men who have recovered their condition may still transmit the virus through their semen up to seven weeks after recovery . Human blood and secretions are contagious when they contain a virus. A laboratory-infected male case isolated Ebola from its semen up to day 61 after onset.

It is often the case that health care workers get infected when treating suspected or confirmed patients with Ebola virus disease. This is caused by close contact with the patient without strict adherence to infection control precautions.

In the presence of contacts with monkeys or pigs infected with Reston Ebola, several human infections have been recorded and there are no clinical symptoms. Therefore, the Reston Ebola virus seems to be less virulence in humans than other Ebola populations.

However, the only evidence available is from healthy adult males. It is still too early to make an inference about the health effects of the virus on all populations, such as those with impaired immunology, those with basic medical conditions, pregnant women and children. More research is needed on the Reston Ebola virus before a clear conclusion can be made about the pathogenicity and virulence of the virus in humans.

Popular situation

  • The Ebola virus was first discovered in 1976 near the western provinces of the equatorial Sudan and around Zaire (now the Democratic Republic of the Congo). Between June and September 1976, Sudan found 284 Ebola-infected people and 117 died. In Zaire, there were 318 cases between September and October of the same year, and 280 people died of the disease. In 1977, there was a case in Zaire, and in 1979, the Sudan broke out again.
  • In 1995, Kikwit in Zaire showed a major epidemic, with 315 infections and 244 deaths.
  • In 1994-95, one case of human Ebola hemorrhagic fever and several cases of chimpanzee infection were confirmed in Côte d’Ivoire.
  • In Gabon, Ebola hemorrhagic fever was first discovered in 1994 and two outbreaks occurred in February and July of 1996.
  • An outbreak occurred in northern Uganda in the fall of 2000.
  • Since March 2014, the three West African health ministries in Guinea, Liberia and Sierra Leone have continued to report new cases and deaths caused by Ebola virus disease.

Symptoms and signs

The incubation period for Ebola virus disease ranges from 2 days to 21 days. The disease can mainly cause damage to various organs such as liver, spleen and kidney. The main symptoms are fever , extreme weakness, muscle pain , headacheand sore throat . Then there will be vomiting , diarrhea , rash , impaired kidney and liver function and in some cases there will be internal bleeding and external bleeding . Test results comprising white blood cell counts and platelet counts , and the liver enzymes will be increased.

The disease has different performances at different times after the onset of the disease:

  • Two to three days after the onset of vomiting , nausea , diarrhea, mucus or bloody stools , and there may be diarrhea that lasts for several days.
  • Duration of 4 to 5 days at this time has entered the very period , the very period bleeding is a common thing, in general there is vomiting blood , black stools , injection site bleeding, epistaxis , hemoptysis , etc., in particular, noted that pregnant women appear miscarriage and postpartum hemorrhage ; In addition, there will be persistent fever, there will be changes in consciousness; may be complicated determined myositis , pneumonia and so on.
  • The course of the disease may occur in 6 to 7 days . The measles -like rash is mainly composed of the shoulders, palms , and soles of the feet. The whole body organs may be spread and desquamation after a few days .
  • Patients with severe illness or severe complications from 8 to 9 days may die during this period, mainly due to liver and kidney failure .

If the virus persists in semen , it can cause orchitis , testicular atrophy, and the like.

Diagnosis of Ebola virus disease

In other diseases may be made before the diagnosis of Ebola virus disease should be excluded include: malaria , typhoid fever , shigellosis , cholera , leptospirosis , plague , rickettsial disease , relapsing fever , meningitis , hepatitis and Other viral hemorrhagic fever .

Ebola virus infection can be clearly diagnosed in the laboratory through several types of tests:

  • Antibody capture enzyme-linked immunosorbent assay (ELISA)
  • Antigen detection test
  • Serum neutralization test
  • Reverse transcription polymerase chain reaction (RT-PCR)
  • Electron microscope
  • Virus isolation was performed by cell culture .

Patient samples are at risk of extreme biohazard; testing is only possible at the highest level of bioprotective conditions.

Prevention of Ebola virus disease

There is no specific vaccine for Ebola virus disease . Several vaccines are being tested, but no vaccine is available for clinical use. The popularity of the Ebola virus is mostly due to the hospital environment, poor public health, needles that are discarded everywhere, and lack of negative pressure wards pose a great threat to health care workers. Because of better equipment and hygiene, in modern hospitals, the Ebola virus is almost impossible to explode.

Control infection in health care institutions

The interpersonal transmission of Ebola virus is mainly related to direct or indirect contact with blood and body fluids. Health care workers have been reported to have been infected when appropriate infection control measures have not been taken.

Because the initial symptoms may not be specific, it is not always possible to detect Ebola patients early. Therefore, it is important that medical staff ensure that standard precautions are consistently applied to all patients and all care operations, regardless of their diagnosis. These include basic hand hygiene, respiratory hygiene, the use of personal protective equipment (according to other risks of spillage with infectious materials), safe injection practices and safe landfill practices.

Health care workers who care for suspected or confirmed patients with Ebola should take infection control measures in addition to standard protective measures to avoid any contact with the patient’s blood and body fluids, and in the absence of protection and possible Direct contact with the infected environment. When in close contact with Ebola patients (within one meter), health care workers should wear facial protection (masks or medical masks and safety glasses), clean but non-sterile long-sleeved gowns and gloves (some operations) The procedure requires sterile gloves).

Laboratory staff are also at risk. Diagnostic specimens collected from suspected human and animal cases in Ebola should be handled by trained personnel and processed in appropriately equipped laboratories.

Reduce the risk of human infection with Ebola

In Africa, when Ebola virus disease outbreaks occur, the risk reduction public health education content should focus on the following aspects.

  • Reduce the risk of wildlife and human transmission from exposure to infected fruit bats or monkeys/gorillas and the consumption of raw meat from such animals. Gloves should be worn and other appropriate protective clothing should be worn when handling animals. Such animal products (blood and meat) should be thoroughly cooked before consumption.
  • Reduce the risk of interpersonal transmission in society due to direct or close contact with infected people, especially with their body fluids. Close physical contact with Ebola patients should be avoided. Gloves and appropriate personal protective equipment should be worn when caring for patients at home. After visiting the inpatient and caring for the patient at home, wash your hands regularly.
  • Communities affected by Ebola should educate the public about the nature of the disease and the control measures of the epidemic, including the burial of the deceased. Patients who die in Ebola should be buried immediately and safely.

Gloves and other appropriate protective clothing should be worn when handling infected animals or their tissues and slaughtering animals. In areas where the Reston Ebola virus has been reported in the herd, all animal products (blood, meat and milk) should be thoroughly cooked before consumption.

Treatment of Ebola virus disease

Critically ill patients need to receive critical support. Patients often experience dehydration and require oral rehydration or intravenous infusion with fluids containing electrolytes.

Treatment is first aided, including minimizing viral invasion, balancing electrolytes, repairing lost platelets to prevent bleeding , maintaining oxygen levels in the blood , and treating complications .

Exclude individual cases of Ebola rehabilitation ‘s serum in the treatment of disease and no effect.

Interferon is also ineffective against Ebola. In the monkey test, coagulation interferon appeared to play a role in surviving 33% of the original 100% dying infected monkeys. Scientists at USAMRIID claim that three of the four macaques infected with Ebola recovered.

Currently on the Ebola virus disease there is no effective method of treatment that some antiviral drugs such as interferon and ribavirin invalid, mainly to support and symptomatic treatment, including attention to water and electrolyte balance, control bleeding; renal failure were when dialysis treatment Wait.

The treatment of patients with Ebola virus disease with plasma from convalescent patients is still controversial.

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