Infection occurs when germs, which are tiny single-cell organisms such as bacteria or viruses, enter the body and multiply. Symptoms, such as fever, fatigue or a rash, result from the immune system’s response to rid the body of the invaders. Infections can affect any part of the body, but the most serious infections occur in the blood or heart and can be life-threatening.
Germs can be spread by direct contact, such as touching infected skin or mucous membranes (like the eyes or nose). They can also be transmitted through indirect contact, such as sharing a toothbrush or cutlery with someone who has an infectious disease or through sexual transmission of diseases like herpes or genital warts. Some infections are spread by airborne droplets, such as when people who have an infection cough or sneeze. Some germs are carried in food (especially if it’s unwashed or uncooked), water or animals. They can also be spread by mosquitoes, fleas or ticks.
Microorganisms can be very successful in the environment because they reproduce far more quickly than humans and adapt to their surroundings through a process called natural selection. As a result, they have many more genetic variations than humans do. However, these differences can also make it easier for some microorganisms to cause disease in humans. This is why it’s important to follow guidelines and recommendations that healthcare professionals can use to prevent infection. These include transmission-based precautions and germ-specific guidelines that providers can follow to reduce the risk of healthcare-associated infections (HAIs) in the hospital.
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