Viruses are pieces of genetic material that can enter the body and destroy cells. Some viruses can pass from person to person through the air, while others are exchanged through bodily fluids. Learn about some of the more well-known viruses here.
A mask can help protect against airborne viruses.
Hepatitis
Hepatitis viruses infect the liver and come in a variety of types with differing levels of severity. For example, hepatitis A sometimes requires no treatment, while hepatitis B can cause liver cancer or liver failure.
HIV/AIDS
HIV is a virus that affects the immune system and makes it harder for infected people to fight off other diseases. The advanced stage of infection is called AIDS.
Influenza
Commonly known as "the flu," influenza symptoms are rarely severe and can include fatigue, aches, nausea and respiratory problems. Annual vaccines are available, and the Mayo Clinic recommends them for children, the elderly and people who regularly work around either group.
Herpes
Herpes can cause itching and blisters, although many people won't experience these symptoms. According to the Mayo Clinic, up to 90 percent of people with herpes are not aware that they have it.
Smallpox
The variola virus causes smallpox, which has been wiped out worldwide thanks to vaccines. Throughout much of the world's history, smallpox was a devastating disease that caused lesions and often led to death.
Tags: Mayo Clinic