infections
Development of Infection
Introduction
Infectious diseases are usually caused by microorganisms that invade the body and multiply. There are many Types of Infectious Organisms (see also The following are some examples of how microorganisms can invade the body: Through the mouth, eyes, or nose Through sexual contact Through wounds or bites Through contaminated medical devices People can ingest microorganisms by swallowing contaminated water or eating contaminated food. They may inhale spores or dust or inhale contaminated droplets coughed or sneezed out by another person. People may handle contaminated objects (such as a doorknob) or come into direct contact with a contaminated person and then touch their eyes, nose, or mouth. Some microorganisms are spread through body fluids such as blood, semen, and stool. Thus, they can invade the body through sexual contact with an infected partner. They also can enter through nonsexual contact with body fluids, such as while providing personal care or medical services. Human and animal bites and other wounds that break the skin can allow microorganisms to invade the body. Infected insects and ticks can spread diseases when they bite. Microorganisms can also adhere to medical devices (such as catheters, Artificial Joint Infectious Arthritis , and After invading the body, microorganisms must multiply to cause infection. After multiplication begins, one of three things can happen: Microorganisms continue to multiply and overwhelm the body’s defenses. A state of balance is achieved, causing chronic infection. The body—with or without medical treatment—destroys and eliminates the invading microorganism. Invasion by most microorganisms begins when they adhere to cells in a person’s body. Adherence is a very specific process, involving "lock-and-key" connections between the microorganism and cells in the body. Being able to adhere to the surface of a cell enables microorganisms to establish a base from which to invade tissues. Whether the microorganism remains near the invasion site or spreads to other sites and how severe the infection is depend on such factors as the following: Whether the microorganism Production of toxins and enzymes None Whether it develops Antibiotic Resistance None Whether it can block the Defenses Against Infection None How well the person's Overview of the Immune System is functioning Many disease-causing microorganisms have properties that increase the severity of the diseases they cause (virulence) and that help them resist the body’s defense mechanisms. These properties include the following: Toxins Enzymes Ways to block the body's defenses 