Viruses are infectious agents found in almost all life forms. The viruses are made up either of DNA or RNA, surrounded by a capsid, a protein coat. Viruses are between 20 and 100 times smaller than bacteria, or about 450 nanometers(.000014), being the largest, to 30 nanometers(0.000001 in.) being the smallest which make them virtually impossible to be seen by light microscopes. Viruses often damage or even kill the cells they infect. They reproduce by releasing their nucleocapsid, or a copy of their DNA, into the cell. In the cell, the virus replicates itself through a series of events, which afterward produce the new viruses which either kill or damage the cell they need to reproduce.

Bacteria are microorganisms that lack the internal cell membranes that other cells do. Bacteria are connected to the lives of all organisms, they either help or harm the organism they are in. Bacteria are made up of DNA which have a circular arrangement. They can move around by flagella, which are hairlike extensions, and can attach themselves to small objects known as pili. Bacteria are usually about 1 micron(.00004 in.) in length. Single bacterium can not be seen with the naked eye, but can be seen with a microscope, while a whole colony of bacteria can be seen with the naked eye. The bacteria are usually rod shaped, and they reproduce asexually, in which a copy of the DNA is made, and then the outer membrane of the bacterium begins to grow inward and divides the bacterium into two identical cells.

Three of the many bacterial viruses consist of diseases such as anthrax, syphilis, and gonorrhea. Anthrax is caused by bacterium bacillus anthracis, which is a type of bacteria. It causes rise of body temperature, trembling, or even death. The disease has a vaccine made of culture filtrte. Syphilis is caused by spiral-shaped bacteria that penetrates the mucus membranes in the body. It causes a painless, red sore. Syphilis can be treated by the antibiotic, penicillin. Another diseases is gonorrhea, which is caused by the gonococcus bacterium. It causes discharges from the penis, vagina, or rectum. It also causes a sore throat. It can be treated by penicillin.

Three of many viral diseases consist of ebola, dengue fever, and polio. Ebola is a very dangerous virus that is caused by the ebola virus. The main symptoms consist of fever, weakness, muscle pain, headache and a sore throat. Dengue fever is caused by aedes albopoctus. It's symptoms are fever, headaches, eye-aches, pain in the muscles and the joints, runny nose, and skin rashes. There is no cure for this disease. Finally, polio is caused by the poliomyelitis virus. It's symptoms are fatigue, headache, fever, constipation, diarrhea, and pain. You can prevent this virus by vaccination.

I think that viruses cause a greater risk to humans because the viruses reproduce very rapidly, and there are not many things to prevent it. Another thing is that it's symptoms are much more life threatening, like dengue fever, and there is not a very good way to stop reproduction, while on the other hand, in bacterial infections, you can take antibiotics which destroy the bacteria's membrane, which help your immune system to kill it of. Another thing is that viruses evolve very quick at evolving, for example, the HIV virus was thought to have been evolved by a monkey disease. So I think that viruses pose more of a threat because they are very fast evolvers, and very hard to find vaccinations for them.