Infection is the body’s response to harmful organisms, such as viruses, bacteria, fungi or parasites. Infections can occur when microorganisms, like germs, enter the body through skin-to-skin contact, the transfer of bodily fluids, inhaling droplets or saliva or contaminated food or water. Viruses, bacteria and fungi can cause many different infections including the common cold, flu, stomach flu, pneumonia, viral hepatitis, STIs, foot fungus, and more. Some infections are chronic while others are acute or life threatening.
Most infections are caused by viruses which are tiny single-celled organisms that use the host to complete their life cycle and reproduce. Viruses can cause many common illnesses including the common cold, flu, measles, chicken pox, herpes simplex and HIV. Some viral infections may be chronic while others are acute and often have clear symptoms and a quick course of illness.
Bacterial infections are usually more serious than viral infections and can be caused by bacteria that enter the body through skin-to-skin, blood flow, urination or the mouth. Bacteria are small, single-celled microorganisms that can be seen with a low-powered microscope and come in three shapes: spherical (coccus), rodlike (bacillus) and curved (vibrio, spirillum or spirochete).
Antibiotics can treat most bacterial infections. However, antibiotic resistance is a growing problem and so it is important to use antibiotics only when they are needed. Some infections can lead to a dangerous inflammation in the whole body called sepsis, which happens when a lot of bacteria enter the bloodstream.
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