ebola, pathogenesis, symptoms, transmission, diagnosis, treatment

1. EBOLA
SAAJIDA SULTAANA MAHUSOOK

2. EBOLA VIRUS DISEASE
Strains
Zaire strain
Fatality- 90%
Sudan strain
Fatality- 50%
Mild Reston strain
Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a
rare but 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.

3. TRANSMISSION
• It is thought that fruit bats of the Pteropodidae family are
natural Ebola virus hosts.
• Through close contact with the blood, secretions, organs or
other bodily fluids of infected animals such as fruit bats,
chimpanzees, gorillas, monkeys, forest antelope or
porcupines found ill or dead or in the rainforest.
• human-to-human transmission via direct contact (through
broken skin or mucous membranes) with:
• Blood or body fluids of a person who is sick with or has died
from Ebola
• Objects that have been contaminated with body fluids (like
blood, feces, vomit) from a person sick with Ebola or the
body of a person who died from Ebola

4. PATHOGENESIS
• Ebola virus enters the patient through mucous membranes, breaks in the
skin, or parenterally and infects many cell types, including monocytes,
macrophages, dendritic cells, endothelial cells, fibroblasts, hepatocytes,
adrenal cortical cells, and epithelial cells.
• The incubation period may be related to the infection route (6 days for
injection versus 10 days for contact).
• Ebola virus migrates from the initial infection site to regional lymph
nodes and subsequently to the liver, spleen, and adrenal gland.
• Although not infected by Ebola virus, lymphocytes undergo apoptosis
resulting in decreased lymphocyte counts.
• Hepatocellular necrosis occurs and is associated with dysregulation of
clotting factors and subsequent coagulopathy.
• Adrenocortical necrosis also can be found and is associated with
hypotension and impaired steroid synthesis.
• Ebola virus appears to trigger a release of pro-inflammatory cytokines
with subsequent vascular leak and impairment of clotting ultimately
resulting in multiorgan failure and shock.

5. SYMPTOMS
• Symptoms may appear anywhere from 2 to 21 days after contact with the virus, with an
average of 8 to 10 days.
• The course of the illness typically progresses from
• “dry” symptoms -such as fever, aches and pains, and fatigue)
• “wet” symptoms (such as diarrhea and vomiting) as the person becomes sicker.
• Primary signs and symptoms
• Fever
• Aches and pains, such as severe headache, muscle and joint pain, and abdominal
(stomach) pain
• Weakness and fatigue
• Gastrointestinal symptoms including diarrhea and vomiting
• Abdominal (stomach) pain
• Unexplained hemorrhaging, bleeding or bruising
• red eyes, skin rash, and hiccups (late stage).
• Many common illnesses can have the same symptoms as EVD, including influenza (flu),
malaria, or typhoid fever.
• Recovery from EVD depends on good supportive clinical care and the patient’s immune
response.
• Studies show that survivors of Ebola virus infection have antibodies (proteins made by the
immune system that identify and neutralize invading viruses) that can be detected in the
blood up to 10 years after recovery. Survivors are thought to have some protective
immunity to the type of Ebola that sickened them.

6. DIAGNOSIS
• It can be difficult to clinically distinguish EVD from other infectious diseases such
as malaria, typhoid fever and meningitis. Confirmation that symptoms are caused
by Ebola virus infection are made using the following diagnostic methods:
• antibody-capture enzyme-linked immunosorbent assay (ELISA)
• antigen-capture detection tests
• serum neutralization test
• reverse transcriptase polymerase chain reaction (RT-PCR) assay
• electron microscopy
• ·virus isolation by cell culture.
• nucleic acid tests (NAT)
• Rapid antigen detection tests.
preferred specimens for diagnosis:
• Whole blood collected in ethylenediaminetetraacetic acid (EDTA) from live patients
exhibiting symptoms.
• Oral fluid specimen store

7. TREATMENT
Supportive care - rehydration with oral or intravenous fluids -
and treatment of specific symptoms.
a range of potential treatments including blood products,
immune therapies and drug therapies are currently being
evaluated.
The rVSV-ZEBOV vaccine is being used in the ongoing 2018-
2019 Ebola outbreak in DRC.

8. https://www.cdc.gov/vhf/ebola/symptoms/index.html
https://www.who.int/news-room/fact-sheets/detail/ebola-
virus-disease
https://www.cdc.gov/vhf/ebola/clinicians/evd/clinicians.html