The 2014 outbreak of Ebola has caused a global scare, but this viral disease is not new. It was first identified in 1976, and it most likely has existed for far longer. Since 2000, there has been an outbreak almost every year. However, the current outbreak seems to be a worldwide concern as it is far more widespread than initially thought and may be crossing borders due to global travel patterns. The fact is that Ebola has a 90% mortality rate, meaning that 9 out of 10 people who contract the infection will die. But new drugs have carried the promise of a cure, although none have as yet been approved for treating Ebola.
What is Ebola?
Ebola is a virus which causes a viral hemorrhagic fever. It is also referred to as Ebola hemorrhagic fever (EHF) or Ebola virus disease (EVD). Ebola is just one of about 30 viruses that can cause viral hemorrhagic fever. It is native to Africa, and is mainly seen in remote villages near the tropical rain forests of Central and West Africa. Another virus that is closely related to Ebola is the Marburg virus which also causes a viral hemorrhagic fever.
The virus can affect several organs in the body. It blocks the immune cells thereby preventing an effective immune response from eliminating the virus, and it targets the endothelial cells of blood vessels. Eventually the infection damages blood vessels which leads to bleeding. This is a characteristic feature of Ebola and other hemorrhagic fevers. However, bleeding from the eyes and orifices is a late sign of the disease and often arises when the chance of recovery is very slim.
Picture of the Ebola virus with an electron microscope
Facts About Ebola
The are 5 species of the Ebola virus:
- Sudan ebolavirus
- Zaire ebolavirus
- Tai Forest ebolavirus (also known as Ivory Coast ebolavirus or Côte d’Ivoire ebolavirus)
- Reston ebolavirus
- Bundibugyo ebolavirus
The current 2014 outbreak is believed to be due to the Zaire ebolavirus species, which is the most deadly type.
Origin of Ebola
The origin of Ebola is unclear. It was identified in 1976 when advances in medical technology made it possible to do so. The Marburg virus was identified about 10 years earlier. However, most Ebola infections occur in Africa, particularly Central and West Africa. Infection with a less serious species of Ebola virus has also been identified in Asian nations like the Philippines but this does not cause human disease.
The natural reservoir for the Ebola virus remains unknown. A natural reservoir is that organism which carries the virus in the long term but usually does not get the disease itself. Monkeys are not the natural reservoir of Ebola as is sometimes incorrectly thought. Currently there are theories about bats, plants and insects being the natural reservoirs. Bats appear to be favored among the medical community as the natural host but this has not been conclusively ascertained as yet.
There is currently no vaccine to prevent Ebola infections. There is extensive work being done in the field and a variety of vaccines are under development. Some early results are promising but as yet an effective and safe vaccine that can be used in immunization programs does not exist. Using blood products from a survivor of Ebola infection to treat others is not a vaccine.
Death from Ebola
The mortality rate of Ebolavirus disease (EVD) is as high as 90%. This means that up to 9 out of 10 people infected with the Ebola virus will die. However, this statement can be misleading because some species of the Ebola virus are not as deadly. The Bundibugyo ebolavirus has a mortality rate of 25% and the Reston ebolavirus is not known to cause human disease. Most Ebola deaths are a result of infection with the Sudan ebolarvirus and Zaire ebolavirus.
Spread of Ebola
The routes of transmission is very important to understand in order to effectively combat the continuing spread of the disease. It is difficult to conclusively identify the starting point of the spread of the Ebola virus as the natural host for this virus is as yet unidentified. The popular theory at this stage points to bats being the natural reservoir of the Ebola virus.
Human and non-human primates contract the infection from contact with blood, saliva, infected tissues, feces or urine of an infected animal, and possibly the host. It can then be spread from one infected person to another. However, Ebola cannot be spread by insects in a way that it may carried from one person to another. It also cannot spread through the air.
People who travel to endemic areas in Africa, make contact with animals (especially primates) from endemic areas, or work with people from these areas are at the greatest risk of contracting the infection. Family members are therefore among the highest risk group if they care for a relative who has the disease.
Medical professionals are also at risk, especially if they do not work with the necessary protective gear when attending to patients with Ebola. This also includes medical scientists who work with the corpses of dead animals that were infected with Ebola, as part of their research on the disease. Contaminated needles and syringes may also be a risk.
Signs and Symptoms
The first signs and symptoms of Ebola virus disease arises about 8 to 10 days after infection. This delay is known as the incubation period. It can be slightly shorter (like 3 days) in primary exposure, which occurs when people travel to an endemic area. It may be slightly longer in secondary exposure (up to 21 days) is secondary exposure, which is when it is transmitted from one person to another, or from an animal to a human or through contact with infected tissues.
- Severe headaches
- Sore throat
- Skin rash
- Joint and muscle pains
- Eye redness
These symptoms are non-specific and similar to many other viral infections. People who show these symptoms after traveling to endemic areas or coming into contact with people who have Ebola should seek immediate medical attention for what may seem like the flu.
- Nausea and vomiting
- Cough, usually with chest pain
- Abdominal pain
- Diarrhea, sometimes bloody stool
- Bleeding from the eyes and later from the body orifices (ears, nose, rectum)
- Internal bleeding, including bleeding in the organs like the brain
- Severe weight loss
Sometimes early symptoms may only appear later in the disease.
As yet there is no effective drug to treat Ebola. The antivirals that are currently available for human use have not proven to be effective against the virus. Instead the focus of treatment is on supportive care. This requires adequate bed rest, plenty of fluids with electrolytes, controlling symptoms like changes in blood pressure and administering oxygen where necessary. Blood transfusions may also be necessary.
Ebola virus seems to interfere with the immune system thereby preventing it from attacking the virus. However, some people are able to still survive the infection for reasons that are not as yet understood. It is important to note that no herbal remedy or nutritional supplement has been shown to be able to treat Ebola.
Depending on the species of the Ebola virus involved in the infection, the prognosis may be very poor. Zaire ebolavirus is the most deadly. Most people die within 2 weeks but those few patients who do survive generally make a slow recovery. There are a number of complications that can arise among survivors, like ongoing muscle pain and joint aches, fatigue, headaches, hearing disturbances, cessation of menses (amenorrhea) and gland infections such as orchitis and parotitis.