Ebola virus disease

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Ebola is a viral disease that rapidly presents symptoms after a subject has been come in contact with the virus. These symptoms are common among tropical diseases thus rendering diagnosis particularly difficult. Ebola is transmitted through the passage of body fluids from an infected individual; this refers to direct contact or contact with an object that has previously been contaminated by someone who is host to the virus.

The Ebola virus is part of the family Filoviridae. The Ebola virus genome is single stranded negative sense RNA. It is 19 kb in size. The genome has 7 open reading frames coding for the 7 or 8 known structural proteins. The first case of the Ebola disease was recorded in Sudan and Zaire in 1976. Since then the number of outbreaks of the diease has continued to increase.

Contents

Epidemiology

It has been suggested that Fruit bats are the resevoir for the Ebola virus. The bats can only transmit Ebola to humans by direct contact with the bat excretions or saliva. Futhermore, it is known that non-human primates can be infected with Ebola, they can then transmit the virus to humans. Again this is only through contact witht the animal's bodily fluids. These outbreaks seem to happen at the end of the rainy season in Sub-Saharan Africa. 

Pathogenisis and Pathology

Once individual is infected with Ebola dessimation and necrosis of the organs occurs. This generally tends to occur in the Liver, Spleen and Kidneys where there are high levels of the virus. In all these organs there is an increase in vascular permeability due to damage of the Endothelial Cells. TNFα and other various interleukins which are pro-inflammatory cytokines are all involved in the pathogensis of Ebola. Filoviruses are also thought to surpress the hosts adaptive immune response. DIC is a secreted virus glycoprotien, it is thought to stop IFN and also antiviral RNA interference. 

Symptoms

As stated, the symptoms of EVD (Ebola virus disease) are similar to other tropical diseases such as Dengue fever and Malaria. The National Health Service (NHS) of the UK report that “A person infected with Ebola virus will typically develop a fever, a headache, joint and muscle pain, a sore throat and intense muscle weakness”.[1]
These symptoms are also presented in many non-fatal diseases however the mortality rate of EVD is particularly high. The World Health Organisation (WHO) states “the average EVA case fatality rate is around 50%”[2] whereas the NHS claim a figure of 50-90% of cases.[3] Given the high mortality rate and ease of transmission to those in a close proximity a swift EVD diagnosis is often not only critical for the patient but also others.

Diagnosis

The process in which someone is diagnosed with EVD is difficult because of the generic nature of the symptoms and the severity of the disease. Without many distinguishable symptoms EVD is open to be misdiagnosed as another disease and an inappropriate treatment and care plan could be administered. The severity of the disease also increases the complexity of diagnosis as those who are presenting symptoms but go undiagnosed are encouraged to ring forward rather than visit a physician so they can remain in isolation until the proper arrangements for treatment and care can be made. Diseases that are transmitted through bodily fluids are notorious for rapid outbreaks within close-knit clinical settings. This can be observed by the rapid outbreak in West African countries whom may not have the facilities or infrastructure in place to pre-emptively isolate patients appropriately.

The Centre for Disease Control (CDC) is a public health institution based in America devoted to the prevention and control of disease; they present a concise table on their website stating the diagnostic tests available to ebola sufferers based upon the length of time a patient has been infected with the virus.

Ebola.png[4]

The diagnostic tests presented by the CDC involve handling the body fluids and tissues of those who have been infected with the disease and thusly amplify risk of transmission if not carried out safely.

Preventions and Precautions

Resevoir control is important; this means avoiding contact with bats. It is advised to not enter caves and mines in endemic areas. Also humans working with infected non-human primates should wear protective clothing similar to those which healthcare staff wear when treating an infected individual. 

Currently, Ebola has no licensed treatment available so precautionary measures are emphasised to contain outbreaks and prevent the spread of disease. This includes patient isolation which forms the backbone of many plans put into place by governments around the world. Hospitals will implement the technique of strict barrier nursing. Even after all these strict precautions healthcare staff are still most at risk. In light of the outbreak in March 2014 the UK Prime Minister, David Cameron, has allegedly “urged other European countries to start Ebola screenings at airports” [5]. This approach is formulated on the understanding that the 2014 outbreak originated in West Africa and that European countries are at minimal risk due to being a great distance from the site of origin [6][7].

References

  1. http://www.nhs.uk/Conditions/ebola-virus/Pages/Symptoms.aspx
  2. http://www.who.int/mediacentre/factsheets/fs103/en/
  3. http://www.nhs.uk/Conditions/ebola-virus/Pages/Symptoms.aspx
  4. http://www.cdc.gov/vhf/ebola/diagnosis/
  5. http://www.bbc.co.uk/news/uk-29654823
  6. Farrar J et al. 2014. Manson's Tropical Diseases. United States. 23rd ed. Elsevier Saunders.
  7. Collier L et al. 2011. Human Virology. 4th Ed. Oxford. Oxford University Press.




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