Definition:
A microscopic organism that can only grow inside of a living cell. Viruses can cause infection, illness, and disease in all living organisms and can be found in any environment where life is present.
Facts:
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Antibiotics do not help in the treatment of viruses.
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Viruses cannot be seen with a standard light microscope, but can be viewed with an electron microscope
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A process called Negative Staining is used to provide greater contrast between the virus and the background, as shown above, which allows for easier viewing and identification of the particles
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some viruses will only infect a specific organism such as plant or animal
Particle Size:
The largest virus particle is about the size of the smallest bacteria. Most viruses fall in the range of .01 - .3 microns. Since "unattached" viruses can be so small, in the range of 100 times smaller than the average bacteria particle, they can be very difficult to filter outside of a true HEPA environment like that of a lab, hospital, or cleanroom.
"Attached" viruses can be carried in dust, pet hair, allergens, and most commonly in coughs and sneezes. These larger attached particles, fortunately, can be captured by a higher-rated pleated filter in standard residential applications.
Airborne Virus Transmission:
Viruses may be transmitted in a variety of methods. When considering air filtration and filterable particles, the focus is on airborne and respirable virus particles. These are dispersed and spread by coughing and sneezing and can be introduced to another host through the mouth, nose, or eyes. The following are a list of illnesses that can be spread through respiratory contact:
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common cold
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influenza
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strep throat
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chicken pox
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bacterial meningitis
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whooping cough
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tuberculosis