How Long Does a Virus "Live" Outside a Host?

Some viruses can "live" undisturbed for years. Others are so fragile that they can only withstand "external" conditions for mere minutes if not seconds. This hub will name a number of viruses and define their "life expectancy" outside a host cell.

Imagine that this "outside a host cell" is a doorknob, telephone receiver, computer keyboard, or play-yard.

Note that scientists are somewhat divided on whether or not a virus is actually a living thing. Some claim that the fact that it contains RNA means it is living. Others claim that since it lacks mitochondria (the powerhouse of living cells) it is a non-living particle similar to a crystal.

In describing a surface on which a virus can "live" the assumption is that it is not in direct sunlight, is not exposed to cleaning chemicals, and is in a temperature controlled environment or one that is neither too hot or too cold.

Another way to put this is an environment that most humans would find comfortable.

This virus has the Latin name Variola major with a secondary version called Variola minor. Variola is Latin for "spotted." It is believed that this virus is 12,000 years old.

Smallpox is estimated to have been responsible for three hundred (300) to five hundred (500) million deaths worldwide in the last century.

A smallpox virus at room temperature in an undisturbed environment could remain viable for years if not decades. Fortunately, smallpox has been eradicated.

Hepatitis A & B are viruses that typically attack the liver. Roughly ten million people a year are infected with this virus. Symptoms become apparent in from two to six weeks. Almost all who contract one of these two viruses overcome the infection and retain lifelong immunity against them.

Hepatitis C is a more serious version of the virus with approximately three hundred million infected worldwide. Hepatitus C can spontaneously "clear" meaning a person's immune system can get rid of it, but for most who have contracted it the virus will go on to cause liver problems including cirrhosis and cancer.

Hepatitis A&B viruses can live, undisturbed on surfaces outside a host cell for up to a week.

Hepatitus C requires "blood-to-blood" contact and therefore cannot survive outside a host cell.

This is what is called a "retrovirus." Such a virus can incorporate it's RNA into the host cell's DNA and thereby "hide" from detection. Also, such viruses replicate along with cells as they divide. This way the virus can hide indefinitely within a collection of host cells. Worse, these cells are often the very cells used in immune response.

HIV can typically survive outside a host cell undisturbed for no more than a few hours.

The rhino-virus (rhino meaning "nose" in Latin) is one of the smallest of all viruses. it is responsible for over half of cold symptoms.

Rhino-viruses typically attacks the sinus tract with symptoms typically lasting a week.

These viruses are often transferred from human to human via contact with the skin such as kissing, handshakes, and other forms of non-intimate contact.

A rhino-virus can live undisturbed outside a host cell for up to a day.

This is the virus responsible for Spanish Flu, Avian Flu, and Swine Flu. An infection is often mild lasting no more than a week, but for some it can be quite deadly. The Spanish Flu killed upwards of five hundred million people. To date, Swine Flu has killed six hundred people in the United States.

Influenza typically invades the lungs.

It is thought that influenza viruses can last outside a host cell undisturbed for up to two days.

Viruses are susceptible to a wide variety of conditions and chemicals. In this example I will assume the virus to be eradicated from a surface is the influenza virus.

The flu virus is killed by heat (167-212°F [75-100°C]). It can also be killed with chlorine (household bleach), hydrogen peroxide, soap (dishwashing and hand), iodine based cleaners, and alcohols.

Examples include;

• Hand wipes or gels with alcohol in them
• Rubbing alcohol
• Household hydrogen peroxide (2% concentration)
• Diluted chlorine bleach (4 Tablespoons per gallon of water)
• Bar soap or pump liquid soap
  
• Dishwashing liquids
• Dishwasher soaps
• Direct sunlight (or ultraviolet light source)
• Automatic Dishwasher (with heating element)
• Oven temperatures (baking)
• Boiling water
  

The idea of this particular article is provide the reader with information on just how viruses manage to infect people. If a virus can lie undisturbed on any surface, "alive" and active, it is very easy to touch that surface, then your face or mouth, and acquire an infection that way.

Direct human contact is not the only way to pick up a viral infection.