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The Dope on Dormant Viruses
Dormant viruses can lie within a human host until the proper conditions for their activity are provided. You might think of viruses' as robots that need to take over a factory to make more of themselves. Without that, the viruses are dormant.
Viruses: What are they?
One million PLUS: number of years that viruses have existed since the beginning of life on Earth.
A virus is a very small infectious agent (20-300 nanometers in diameter) with a genome consisting of a single kind of nucleic acid (RNA or DNA) contained within a protein shell.
Size: 20 nanometers: length of the smallest virus. The largest is the size of the smallest bacteria.
Shape: viruses look like rods, filaments, crystals, helixes, polyhedrons and spheres, with added extensions. Almost all human viruses are close to being spherical.
FACT: The discovery of viruses is credited to the St. Petersburg Academy of Science in 1892 by Dmitri Iwanowsk (1864-1920), a Russian botanist. While studying a tobacco disease, he found that the agent causing the disease was small enough to pass through a ceramic filter that was small enough to trap all bacteria. This was beginning of Virology.
1930: the first time a virus is seen by the human eye --- thanks to the introduction of the electron microscope.
Dead or Alive: viruses are not classifiably alive or dead. They seem to be in limbo between each state.
Persistent viruses can enter and exit host cells without killing them.
There are normally very few viruses found within a human being. Unlike bacteria, there are no known viruses whose presence is either essential or particularly beneficial to humans.
- Bornavirus -- BDV or Borna disease virus have been infecting the human genomes for millions of years. In humans, the virus has been linked (albeit inconclusively) to various psychiatric disorders, including schizophrenia.
- Herpes simplex 1 and herpes simplex 2: genital herpes, can lie dormant in the body for a prolonged period of time. The disease has been known to stay dormant for over 10 years in some patients.
- Human herpesvirus-6, or HHV-6: Guess what? You probably have it now.
- HIV: the virus that causes AIDS. Human Immunodeficiency Virus has claimed the lives of more than 25 million people since 1981.
- Epstein-Barr virus (EBV): Belongs to the family of herpes viruses including those that cause cold sores, genital herpes, chickenpox and shingles. Infection with EBV is virtually inescapable; in the US, 95% of all adults will be infected by age 40, and 50% of all children by age 5. Many people don't realize they have been infected because they never feel sick. Once infected however, you harbor the virus for good.
- Chickenpox (the varicella-zoster virus) has been around for thousands of years. It is a highly infectious virus that causes chickenpox and, later in life, can cause shingles. Pre-vaccine, just about everyone born and raised in the United States was infected during childhood and developed the chickenpox rash.
- The hit and hide virus: Respiratory syncytial virus (RSV), a common cold virus causing bronchiolitis in children, can act as a 'hit and hide' virus. The virus can survive for many months or years, perhaps causing long-term effects on health, such as damage to the lungs.
- The Human Papilloma virus: Over eighty different types of HPV have been identified. Different types of the human papilloma virus are known to infect different parts of the body. The most visible forms of the virus produce warts (papilloma's) on the hands, arms, legs, and other areas of the skin. Most HPV's are very common, harmless, non cancerous, and easily treatable.
Lots of questions; No answers.
The connection between viruses and disease is one of the most active areas of medical research. These are among the questions yet to be answered:
- Why are some people susceptible to certain viruses and others are not?
- Why do viruses affect people in varying degrees of severity?
- Why do some viruses disappear and others lie dormant in the body then flare up years later?
Deadliest [Not-So Dormant] Viruses
- HIV is the virus that causes AIDS. Many people who contract HIV live for years with it, but many do eventually die. HIV is usually contracted through contact with blood, semen or vaginal fluid of an infected person. Although many steps can be taken to prevent disease transmission there is still no cure for HIV/AIDS.
- Ebola Virus: Discovered in 1976, this killer virus has killed millions across the world. The virus is transmitted from the host (usually an animal) to the first case-patient. Only a mere 10% of those who contract the disease survive.
- Marburg virus like the Ebola virus is a type of hemorrhagic fever. The two diseases share the same symptoms are almost indistinguishable from each other. This deadly virus has a 50-90% mortality rate
- SARS is a severe respiratory illness caused by the Coronavirus. It became a world issue in 2003 during a major worldwide outbreak, especially concentrated in Asia. An estimated 15% die from the virus.
- The Spanish Flu makes this list of deadly viruses because in 1918 it caused the deaths of 20-50 million people worldwide. The reason it was so deadly is because of its ability to spread easily. The Spanish Flu killed regardless of age or health. There was no cure for the Spanish Flu. Victims were treated for their symptoms. It is roughly estimated that the Spanish Flu had a mortality rate of 2.5%.
- Yellow fever was a devastating plague that was the first virus to be identified by humans. Yellow fever had killed over tens of millions of deaths in past centuries. It was thought to be as a mosquito-borne infection. It was not until 1901 that Walter Reed (1893-1902) discovered yellow fever was caused by a virus.
5 Great Movies about Viruses
- "28 Days Later" (2002) -- Zombies result from a virus.
- "I Am Legend" (2007) -- Will Smith stars in the last of three films based on the Richard Matheson novel of the same name. Smith is a scientist trying to live through each day while trying to find an antidote for the virus that wiped out the planet.
- "Twelve Monkeys" (1995) -- Terry Gilliam directed Bruce Willis as a prisoner sent back in time to deal with, you guessed it, a deadly virus.
- "Outbreak" (1995) --Dustin Hoffman, helps in this fight against an African virus spread by monkeys.
- "The Andromeda Strain" (1971) -- One of the original deadly virus movies. At least monkeys weren't to blame.