Viruses are very small particles that may cause disease in man, animals, and plants. That word “particles” seems a strange way to describe them, so let’s see why it is used Viruses are so small they will pass through the finest filters. They cannot be grown in sugar solutions but will grow and multiply in the presence of living tissue. They are parasites and depend completely upon their host.
Viruses are too small to be seen by ordinary microscopes—they to be photographed through electron microscopes.
Because they are so small and need so many things to make them grow, many scientists think viruses are not living matter at all, but something between living and non-living matter.
Viruses cause many diseases with which we are all familiar. In attacking organs of the body, each group of viruses causes a different group of diseases. Some of the diseases caused by viruses that attack the skin are chickenpox, smallpox, measles, German measles, and fever blisters.
Other viruses cause diseases of nerve tissue, such as rabies, brain fever, and infantile paralysis. The third group of viruses causes diseases in the internal organs. Yellow fever, influenza, the common cold, and viral liver inflammation are of this group.
Is COVID-19 Caused By A Virus Or A Bacteria?
The coronavirus disease (COVID-19) is caused by a virus, NOT by bacteria.