Infections are the result of the body’s inability to fight off foreign microorganisms that may cause damage or disease if left untreated. Infections can be viral or bacterial in nature and might be caused by a fungus or parasite. There are many common infections and some very rare ones, all with varying causes and treatments.

Some common bacterial infections include strep throat, tuberculosis, urinary tract infections, and E. coli. The different types of bacterial infections are caused by many different types of bacteria. Bacterial infections are generally treated with an antibiotic specifically chosen to destroy the infectious bacteria. Some bacterial infections, like strep throat, are internal, while others are external, such as impetigo, a common bacterial skin infection. Oral antibiotics are generally effective at treating both types of infections, and skin infections can often be treated with topical antibiotics.

Viral infections are different than bacterial infections in that they are caused by viruses, which are smaller than a bacterium or fungus. When a virus infects healthy cells, it prevents the cells from doing their job and causes sickness. Viruses usually infect a specific type of cell, which causes viral infections to affect certain parts of the body. A cold is the most common viral infection and generally affects the upper respiratory tract. Influenza is another common viral infection, but symptoms can affect the entire body.

Antibiotics are not effective against viral infections, but in some cases, an antiviral drug may be used to stop the virus from reproducing. Most viral infections must run a natural course and be fought off by the body, but in some cases, bacterial infections occur secondary to viral infections, and so an antibiotic is used.

Fungus is also a common cause of infections, including ringworm, Athlete’s foot, fungal nail infections, and vaginal yeast infections. Fungal infections are caused by fungus that has either been transmitted through contact or has grown as a result of certain conditions of the body. Fungal infections are treated with anti-fungal medication that may be applied as a cream or taken orally.

There are many different causes of infections and different ways of spreading them. It is not possible to prevent all infections, even with a healthy immune system, but the risk for viral infections can be drastically reduced. Frequent hand washing and basic hygienic practices, such as not drinking or eating after someone, covering your mouth when you cough, and using tissues when you sneeze, are all ways to reduce the spread of viral infections.

Signs and symptoms of infections include fever, localized redness or swelling, painful swallowing, and pain in a specific part of the body, such as the throat, ear, or kidney area. If you have an unexplained fever that persists for more than 48 hours, cannot be relieved by common over the counter medications, or rises above 104°F (40°C), you should see a doctor as soon as possible. Only your physician can determine whether you have an infection and how it should be treated.