Ebola virus: What happens in the infected system?


Ebola virus-
one of the deadliest viruses in the world- causes Ebola virus disease or Ebola Hemorrhagic fever. It is a rare but fatal disease. Hemorrhage and internal bleeding is the characteristic symptom of the disease. Utmost care is taken when a person is diagnosed with Ebola Virus Disease. PPE kits are an essential requirement for handling Ebola-infected patients.

Ways of transmission of the Ebola virus

The transmission of the Ebola virus from the infected individual can be via

  • Body fluids like sweat and tears
  • Used needles and equipment
  • Physical and sexual contact

People who hunt or wild butcher game, called bush-meat, are more likely to be prone to the disease. This susceptibility is because bush-meat consists of primates, which are the primary carriers of the virus.

What is the action of the Ebola virus in Fruit bats?

A person can come in contact with the Ebola virus either by previously infected individuals or by a mosquito bite. The potential carrier of the Ebola Virus is Fruit bats. Ebola virus consists of glycoprotein receptors, which help it attach to the cells of the host. The virus on entering the system of fruit bats, using the favorable environment within, begins to reproduce rapidly using the Polymerase of Bat cells.

The genetic material of the virus replicates and undergoes various processes involving transcription and translation, resulting in the production of virus particles, which then aggregate in an arranged fashion to form a whole new virus organism. These particles move out of the cell by lysing the cell membrane of the infected cell.

What is the action of the Ebola virus in the Human host system?

Once the virus enters the system, it starts by attacking the primary immune cells, which are like alarms for triggering an immune action in case of infection. The target cells usually include dendritic cells, which are responsible for activating the T-cells, which in turn activates the whole immune system, including antibodies that fight the pathogen. Dendritic cells usually take in foreign materials and degrade them. The degraded particles are exposed on its surface using the Major Histocompatibility Complex (MHC).

T-cells can induce action in response to antigens expressed with MHC complexes. The glycoprotein receptors present on the exterior help the virus attach to the cell. The cell engulfs foreign material. Somehow, the virus starts replicating within the cell before the cell can induce an immune response, infecting the cell.

This damaged cell then starts producing other inflammatory products, which induce an inflammatory response. These molecules can also cause damage to molecular integrity resulting in hemorrhagic fever. However, when the cell lyses, cytokines are released which wake up the immune system, but, in the case of Ebola-infected patients, the overwhelming release of cytokines causes Hemorrhage.

Similarly, When the virus particle attacks the next cell, it starts replicating, resulting in an increased viral population in the host system.

What is Hemorrhagic fever?

The virus activity in infected individuals results in severe inflammation. As a result, the clotting proteins go into overdrive and form small blood clots that clog blood vessels. These clots interfere with blood flow to vital organs like the liver, brain, or kidneys, leading to organ dysfunction.

Eventually, the body uses all the available clotting factors, and the infected liver can’t make more. Meanwhile, the infected immune cells are going out of control, triggering a chaotic inflammatory response. In turn, the cells that line the body’s blood vessels also become inflamed and start to leak, which leads to the hemorrhagic syndrome.

Signs and symptoms

The early signs and symptoms of the fever show up within 4-21 days of the infection, with an average of 8-12 days. Initial symptoms are ‘Dry symptoms’ like fever, aches, fatigue. It progresses to ‘Wet symptoms’ like Diarrhea and vomiting.

For Ebola, the incubation period is 2-21 days. Besides, the latent period is longer than the incubation period. So, Ebola-infected individuals are not infectious until after the symptoms have started.

What happens after the individual dies?

When the individual passes away, the handling of the deceased body is crucial. PPE kits are an essential requirement while performing ritual practices. A viable virus can persist for at least seven days on surfaces, confirming that transmission from deceased persons is possible for an extended period after death.

Ebola needs a host cell to survive hence called obligatory parasite; it dies when the host cells die. Therefore, unlike common viruses, Ebola cannot survive in the air and need direct contact with body fluid.

How can we survive this deadly disease?

The best chance of survival is a perfectly well functioning immune system and proper treatment. However, training the human immune system for a future attack by using the attenuated virus (vaccine) is a better solution. There are no vaccines discovered yet (at least not legally patented vaccines available in the market).

Related: Zika virus: reason behind microcephalic fetuses

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