Final answer:
Infections are caused by microbes such as bacteria, viruses, fungi, and parasites that enter and grow in the body, which can be spread through touch and enter the body via the mouth, nose, or eyes. Hand washing is essential in preventing infections, and physical barriers like skin protect against microbial entry.
Step-by-step explanation:
What causes infections? Infections are most commonly caused by microbes entering and growing in the body. These microbes, which include bacteria, viruses, fungi, and parasites, can invade your body and multiply, leading to an illness that can trigger symptoms. These organisms can often be spread by touch, especially if someone sneezes and touches a surface that another person then touches. Frequent hand washing is essential to prevent these microbes from entering the body through the mouth, nose, or eyes. Additionally, pathogenic bacteria may sometimes spread disease-causing genes to non-pathogenic bacteria, and bacteria can also develop antibiotic resistance, making it harder to treat infections with antibiotic drugs. It is also essential to consider that physical barriers such as skin and mucous membranes act as primary defenses against pathogens, preventing them from entering the body. However, damage to these barriers, such as cuts or punctures, can allow microbes to access more vulnerable tissue and cause infection.