Ebola and other tropical viruses are related viruses that cause hemorrhagic fevers — illnesses marked by severe bleeding (hemorrhage), organ failure and, in many cases, death.
There are five types of Ebola and while infection with some (such as Ebola Reston, found in the Western Pacific) are so mild that people rarely get symptoms, other types such as Ebola Zaire (found in Africa) may be rapidly deadly.
Ebola and Marburg viruses live in one or more animal hosts, and humans can contract the viruses from infected animals. After the initial transmission, the viruses can spread from person-to-person through contact with body fluids or contaminated needles.
Ebola was identified for the first time in 1976 in the Democratic Republic of Congo, and in Southern Sudan. It is one of about 30 new diseases to affect humans over the past few decades.
Theories on the origins of these diseases are widespread but many of the most frightening appear to have emerged from sub-Saharan Africa. HIV, which leads to Aids, has been linked to a similar virus common in West African monkeys, and the first ever recorded HIV sample was taken from a man in what is now the Democratic Republic of Congo in 1959.
Ebola and a few other haemorrhagic fevers have been responsible for a tiny number of deaths compared to Aids, and the number of symptomatic cases reported outside Africa has been miniscule. But the devastating speed at which they strike and the far higher possibility of transmission from human to human have made the thought of a major outbreak a terrifying prospect.
However, Ebola is not the only viral haemorrhagic fever which claims lives in Africa, and beyond. Marburg fever gets its name from the town in Germany in which it broke out in 1967 and shares its symptoms with Ebola. It claimed seven lives from the 25 people infected in Marburg and Frankfurt. Those initially infected were laboratory workers exposed to African green monkeys which had been imported for research. But the majority of cases occur in Africa.
Other well-known haemorrhagic fevers are:
*Lassa fever – first noticed in the 1960s after an outbreak in Nigeria
*Rift Valley fever – mainly found in sub-Saharan Africa
*Congo-Crimean haemorrhagic fever – found in many parts of Africa, the Middle East and even warmer parts of the former Soviet Union, in which an outbreak is ongoing.
No effective therapy exists for the hemorrhagic fevers caused by Ebola virus and Marburg virus. People diagnosed with Ebola virus or Marburg virus receive supportive care and treatment for complications.
Signs and symptoms of hemorrhagic fevers caused by Ebola virus and Marburg virus start abruptly within a few days to a week or more after infection. Early signs and symptoms include:
*Joint and muscle aches
Over time, symptoms become increasingly severe and may include:
*Nausea and vomiting
*Diarrhea (may be bloody)
*Chest pain and cough
*Severe weight loss
*Confusion, irritability or aggression
*Massive hemorrhaging from many sites, including nose, mouth, rectum, eyes and ears
Scientists first became aware of the potential of Ebola to destroy whole communities in the mid 1970s, when severe outbreaks in Sudan and the former Zaire killed a total of approximately 440 people. The Zaire strain of the virus is the most deadly to date, proving fatal in just under 90 per cent of those who contract it.
The virus is passed on through contact with blood, secretion or bodily fluids of an infected person – those with the disease start to haemorrhage and cough up or vomit blood, so in outbreaks the disease often spreads from patients to the health care workers looking after them.
Symptoms start to appear anytime from two to 21 days later.
However, how and why each outbreak starts is completely unknown. One theory is that there is a reservoir of the virus in bats, which are unaffected by it, and the virus passes from here to non-human primates such as chimpanzees who in turn pass it on to humans who come into contact with them.
By the time symptoms appear, the virus will have reproduced itself many times and spread through the blood to many organs. The major organs it affects are the liver, kidneys, spleen and reproductive organs.
Of the other haemorrhagic fevers, Lassa fever is spread from rodents which are the natural host. Rift Valley fever is spread by mosquitoes, whilst Congo-Crimean haemorrhagic fever is spread by ticks
For most people — including international travelers — the risk of getting Ebola or Marburg hemorrhagic fever is low. The risk increases if you:
*Travel to or work in areas where Ebola virus or Marburg virus outbreaks have occurred, such as Democratic Republic of Congo (DRC), Sudan, Gabon, Cote d’Ivoire and Angola
*Conduct animal research, especially in tropical African forests, or handle primates infected with Ebola virus or Marburg virus
*Provide medical or personal care for people with Ebola hemorrhagic fever or Marburg hemorrhagic fever
*Prepare people who have died of Ebola hemorrhagic fever or Marburg hemorrhagic fever for burial
Ebola and other tropical viruses are hemorrhagic fevers lead to death for a high percentage of people who are affected. As the illness progresses, it can cause:
*Multiple organ failure
Death often occurs less than 10 days from the start of signs and symptoms.
One reason the viruses are so deadly is that they interfere with the immune system’s ability to mount a defense. But scientists don’t understand why some people recover from Ebola and Marburg and others don’t.
For people who survive, recovery is slow. It may take months to regain weight and strength, and the viruses remain in the body for many weeks. People may experience:
*Liver inflammation (hepatitis)
Ebola and other tropical viruses fevers are difficult to diagnose because many of the early signs and symptoms resemble those of other infectious diseases, such as typhoid and malaria. But if doctors suspect that you have been exposed to Ebola virus or Marburg virus, they use laboratory tests that can identify the viruses within a few days.
Most people with Ebola or Marburg hemorrhagic fever have high concentrations of the virus in their blood. Blood tests known as enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (PCR) can detect specific genes or the virus or antibodies to them.
There is still no specific treatment for Ebola – no standard anti-viral therapies such as interferon have any effect. A vaccine has been produced that was 100 per cent effective in protecting a group of monkeys from the disease, but attempts to replicate the success in humans have so far proved unsuccessful. At present if someone beats Ebola, they do it by themselves, albeit with intensive medical support with intravenous fluids, and/or blood transfusions, or oral rehydration with electrolyte solutions. Survivors can be expected to make a full recovery, although occasionally reversible personality changes have been noted in such lucky patients.
Careful barrier nursing and avoidance of contamination with infected body fluids is still the best way to limit an outbreak.
Treatments in development
Scientists have developed vaccinations against both Ebola and Marburg which work on laboratory animals, and there are promising signs of some therapies that can be used on people affected. Some experiments use antibodies from the marrow of Ebola survivors. Much of the scientific work underway is focused on finding the original source of the disease – the reservoir. One project examined thousands of animals in the rainforests of West Africa in a bid to isolate those hosting the virus.
Some scientists say that the growing numbers of so-called emerging diseases are due to increasing forays by humans into the tropical forests. This brings them into contact with new creatures – and new infections – making it possible there could be even more powerful viruses waiting to play havoc in the human body.
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.
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