Ebola

The Deadly

African Virus

Dr. vibha bhargava

•What is ebola &how does it spread

• Ebola virus disease (EVD) or Ebola hemorrhagic fever (EHF) is a disease of humans and other primates caused by an ebolavirus.

• Symptoms start two days to three weeks after contracting the virus, with a fever, sore throat, muscle pain and headaches.

Ebola Virus Introduction

• First appeared in Africa 1976

• “African Hemorrhagic Fever” – acute,mostly fatal disease– causes blood vessel “bursting”– systemic (all organs/tissues) – humans and nonhuman primates

• Ebola: WHO declares the epidemic as global emergency

• US health authorities had admitted that Ebola's spread beyond west Africa was inevitable. Even medical charity Doctors Without Borders had warned that the deadly virus was now "out of control" with more than 60 outbreak hotspots

In india

•  Health Minister Harsh Vardhan said there is no reported case of the virus in the country and the government is taking all precautions. He said, “As of today, this moment, there is no Ebola case reported in India. There is no need to panic.”

Ebola Taxonomy

Scientific Classification

Order: Mononegavirales

Family: Filoviridae

Genus: Ebola like viruses

Species: Ebola Subtypes -5 types

– Ebola-Zaire, Ebola-Sudan,Ebola-Ivory Coast• disease in humans

– Ebola-Reston • disease in nonhuman primates

Copyrighted Dr. Fre:derick A. Murphy, D.V.M., Ph.D. 1976.

Filoviridae or “Filoviruses”

• Most mysterious virus group

• Pathogenesis poorly understood

• Ebola

– natural history/reservoirs unknown ,

researchers believe the most likely natural

hosts are fruit bats.

– exist throughout the world

– endemic to Africa

– filamentous ssRNA- (antisense) viruses

Image courtesy of the Centers for Disease Control

Ebola Pathogenesis

• Enters Bloodstream– skin, membranes,open wounds

• Cell Level– docks with cell membrane

• Viral RNA – released into cytoplasm – production new viral proteins/ genetic material

• New viral genomes– rapidly coated in protein – create cores

Copyright: Russell Kightley Media, Australia

Ebola Pathogenesis, cont

• Viral cores – stack up in cell– migrate to the cell surface– produce trans-membrane proteins – push through cell surface– become enveloped by cell membrane

• ssRNA- Genome Mutations – capable of rapid mutation– very adaptable to evade host defenses and environmental change

• Ebola is extremely infectious but not extremely contagious. It is infectious, because an very small amount can cause illness. Laboratory experiments on nonhuman primates suggest that even a single virus may be enough to trigger a fatal infection.

• Instead, Ebola could be considered moderately contagious, because the virus is not transmitted through the air. The most contagious diseases, such as measles or influenza, virus particles are airborne.

•  How do people become infected with the virus?• Ebola is introduced into the human population through close contact with the

blood, secretions, organs or other bodily fluids of infected animals. In Africa, infection has occurred through the handling of infected chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found ill or dead or in the rainforest. 

It is important to reduce contact with high-risk animals (i.e. fruit bats, monkeys or apes) including not picking up dead animals found lying in the forest or handling their raw meat.

• Once a person comes into contact with an animal that has Ebola, it can spread within the community from human to human. Infection occurs from direct contact (through broken skin or mucous membranes) with the blood, or other bodily fluids or secretions (stool, urine, saliva, semen) of infected people. Infection can also occur if broken skin or mucous membranes of a healthy person come into contact with environments that have become contaminated with an Ebola patient’s infectious fluids such as soiled clothing, bed linen, or used needles.

tranmission• Health workers have frequently been exposed to the virus when caring for

Ebola patients. This happens because they are not wearing personal protection equipment, such as gloves, when caring for the patients. Health care providers at all levels of the health system -- hospitals, clinics and health posts -- should be briefed on the nature of the disease and how it is transmitted, and strictly follow recommended infection control precautions.

• Burial ceremonies in which mourners have direct contact with the body of the deceased person can also play a role in the transmission of Ebola. Persons who have died of Ebola must be handled using strong protective clothing and gloves, and be buried immediately.

• People are infectious as long as their blood and secretions contain the virus. For this reason, infected patients receive close monitoring from medical professionals and receive laboratory tests to ensure the virus is no longer circulating in their systems before they return home.

Who is most at risk?

• During an outbreak, those at higher risk of infection are:

• * health workers;

* family members or others in close contact with infected people;

* mourners who have direct contact with the bodies of the deceased as part of burial ceremonies; and

* hunters in the rain forest who come into contact with dead animals found lying in the forest.

More research is needed to understand if some groups, such as immuno-compromisaed people are more susceptiblea than others to contracting the virus.

Why it is so deadly• Various infectious diseases like tuberculosis, AIDS and dengue have

killed millions of people all over the world but what distinguishes Ebola from others, is that is highly mysterious..

• It can kill within seven days: Ebola violently multiplies until the viral particles are amplified to about 100 million viral particles in a droplet of blood. Further, without resting in a dormant stage the virus kills the host to find a new one. The fatality rate of the disease is 60 percent.

• There is no vaccine or treatment available: What makes this virus deadly is the fact that researchers have not been able to find an effective treatment or preventive technique to combat the virus and the spread of the disease. The experimental drug Zmapp has shown promising results but the safety and efficacy of the drug are to be evaluated. So, as of now, neither do we have an effective form of therapy nor do we have a vaccine to prevent the disease. 

• Attacks every part of the human body: Ebola only needs a host cell that can help it produce multiple copies of itself. What worsens the condition is the fact that the virus does not need a specific type of cell to multiply (unlike other deadly diseases). According to studies, except for skeletal muscles and bones, the virus is known to infect every part of the human body. Connective tissues, the ones that hold your internal organs in place, are primary targets of the virus.

• Disrupts your immune system: Viral proteins present on the outer surface of the Ebola virus are what destroy the immune system. VP35, one of those proteins, interferes with the production of some important components of the human immune system, like interferons. Another protein traps the white blood cells inside the circulatory system by limiting their movement. As a response to the virus, whatever molecules the immune cells release are used by the virus to devastate the vascular system and activate blood clot formation

• We don’t know where it came from: First of all, scientists have not been able to identify the original reservoir of the virus yet. Bats have been the suspected source but the results are inconclusive. Since a major part of its life cycle remains a mystery, the threat of its recurring outbreak will persist.

• We don’t know all the different ways it can spread: The Ebola virus certainly spreads through direct contact with infectious body fluids and secretions including blood, semen, stool, mucus, saliva and sweat. But there is a possibility that it could spread through other modes, increasing the chances of the disease spreading.

• The virus manipulates your immune system: Once the virus enters the body, it attacks your immune cells, namely macrophages and monocytes. The immune cells get fooled and release large amounts cytokines that instead facilitate the entry of the virus into endothelial cells easily. These cytokines alarm other immune cells to reach the site of infection, exposing them to the virus. While the immune system is still being attacked by the virus, some viral particles that reach the liver start destroying the liver cells to ensures that cell signals are not cleared from the bloodstream.

• Multiplies rapidly: Once inside the body, the virus’s genetic material (single-stranded RNA) begins to multiply rapidly into the host cell. The genetic material is translated to produce viral proteins that form an outer covering of the viral particles protecting its genetic material.

• Releases hundreds of viruses at a time: Within no time, the infected cells becomes packed with blocks or crystals of viral particles. They move towards the cell wall of the infected cell and finally burst the cell releasing hundreds of new viral particles that travel through the blood, attacking healthy cells.

• Destabilises the vascular system: When the new virions are on their way outside the infected host cell, the host cell detaches from its neighbouring cell and loses it contact with the membrane it is rested upon. The viral particles ultimately leave the cell destabilised, causing massive blood loss or hemorrhage.

Prevention

After Death-Virus contagious in fluids for days

• •          Burial use extreme caution

• –        Handling and transport

• –        Cultural practices/ religious belief

• –        Incinerate all waste!!!!

• –        Protective clothing

• –        Body sealed in body bag and coffin

• –        Sanitation of all equipment before and after

• –        Risk for exposure special steps need to be taken to protect the family and community from illness.

Prevention

• No vaccines!

• Patients are isolated

• Medical Staff Training – western sanitation practices

• intake• care during stay• after patient dies

• Infection-control Measures– complete equipment and area sterilization

Treatment

• No Standard Treatment available

• Patients receive supportive therapy• treating complicating infections

• balancing patient’s fluids and electrolytes

• maintaining oxygen status and blood pressure

•Thank you