This lesson will delve into some exotic, but utterly deadly diseases attributed to viruses of the Filoviridae family. Find out what terrible things they cause, as we explore the Ebola virus, the Marburg virus, petechiae, and ecchymoses.
The Filoviridae Virus Family
Fever? Check. Rash? Check. Bleeding out of every orifice of your body until you die? Absolutely. Welcome to the Filoviridae virus family. The viruses in this family are so amazingly deadly, with such a high mortality rate, that the Center for Disease Control classifies them as Biosafety Level Four. This means these viruses pose the highest health, safety and security risk to scientists who work with them, and without a doubt, to any poor chap who may be exposed to them. Let's find out which members of this family are so dangerous and why.
Filoviridae Structure and Transmission
The viruses in this family have a negative sense single-stranded RNA genome encased in a helical capsid that is surrounded by an envelope. The viruses in this family are quite long, like a string. Hence, the name Filoviridae derives its prefix from the term 'filo-,' which means 'thread,' or 'string,' in Latin.
These viruses are spread when humans come into contact with infected animals or other humans. While monkeys are considered as suspects in the spread of this virus to humans, the definitive animal host has not been established in most cases. Regardless, once one human gets a virus from an animal, coming into direct contact with that human, or their bodily fluids and tissues, can cause an infection in a healthy person.
This would be really bad. That's because the reason the viruses in this family are classified as Biosafety Level Four is because viruses in this family are not only considered to be quite exotic in nature, but also because they carry a very high fatality rate, and have no specific treatment. In fact, the fatality rate for this viral family is upwards of 90% in many outbreaks around the world.
Ebola Hemorrhagic Fever
The most famous member of this family is the Ebola virus. This is a virus that causes Ebola hemorrhagic fever. This condition is characterized by the symptoms I mentioned in the introduction, such as fever, joint aches, stomach pain and a rash. Eventually, external and internal bleeding may occur. Internal bleeding may occur in the organs we cannot see, or manifest itself in something called petechiae, which are small, purplish-red spots on the skin that occurs as a result of blood vessel rupture, or ecchymoses, which are large, purplish-red spots on the skin that occurs as a result of blood vessel rupture.
The Ebola virus is mainly located in Africa, although it has the potential to spread to other areas of the world. After a patient is diagnosed with Ebola hemorrhagic fever, there isn't much doctors can do besides what's called supportive care. This is where doctors try to maintain appropriate hydration and electrolyte balance, as well as perform any necessary treatments for secondary infections.
Marburg Hemorrhagic Fever
Unfortunately, Ebola virus isn't alone in causing mayhem in Africa. It has a nasty friend. Although the first cases of this friend, the Marburg virus, were actually recognized in Yugoslavia and Germany, it's a disease that causes outbreaks mainly throughout Africa.
Marburg virus is a virus that causes Marburg hemorrhagic fever. The symptoms of this viral infection, and its consequent disease, are very similar to that of Ebola virus, and start with a fever and abdominal pain, and progress to jaundice, delirium and massive multi-organ failure. It is suggested, although not confirmed, that a fruit bat is the animal reservoir of this virus and that bats spread this virus to monkeys and humans. However, the fruit bat doesn't seem to be affected by the deadly pathogen it spreads.
As with Ebola virus, there is really no known treatment for this disease, and patients are treated symptomatically. Unfortunately, the Marburg virus continues to wreak havoc in Africa. As recently as 2005, an outbreak killed over 200 people in Angola, in what was eventually a 90% case fatality rate.
Although the viruses we covered in this lesson are rare and are usually localized to Africa, whenever and wherever they pop up, they cause near certain death. Hence, these viruses are not to be taken lightly. Let's go over them one more time just to be safe.
The most famous member of this family is the Ebola virus. This is a virus that causes Ebola hemorrhagic fever. This virus may cause external and internal bleeding. Internal bleeding may manifest itself as something called petechiae, which are small, purplish-red spots on the skin that occurs as a result of the rupture of blood vessels, or ecchymoses, which are larger, purplish-red spots on the skin that occurs as a result of the rupture of blood vessels. Unfortunately, the Ebola virus isn't alone in causing mayhem in Africa, as Marburg virus, which is a virus that causes Marburg hemorrhagic fever, causes some of the same terrible problems as the Ebola virus.
After the lesson, students should be able to:
- Describe the structure of Filoviridae viruses
- Understand how Filoviridae viruses are transmitted
- Identify the two main Filoviridae viruses and their symptoms