 Contagious diseases are spread every day. Oftentimes, they are transmitted unknowingly, leaving healthcare staff unprepared for outbreaks. This module provides basic information on the transmission of diseases, as well as how you can use precautions to prevent the spread of infection. Infection is the result of a complex interrelationship between a potential host and an infectious agent. Infections can be caused by bacteria, viruses, fungi, or parasites. The methods of transmission vary by type of organism. Some infectious agents may be transmitted by more than one route. Some are transmitted primarily by direct or indirect contact. An HAI is an infection that develops as a result of medical care. This may occur in a hospital, outpatient surgery center, nursing home, rehabilitation facility, or while receiving wound care services. In order to develop an infection while receiving these services, bacteria must enter your body. Transmission of infectious agents requires three elements. A source of infectious agents. A susceptible host or receiver. A method of transmission for the agent. This is known as the chain of infection. Contact transmission is the most common method of transmission. It is divided into two subgroups. Direct contact and indirect contact. Direct transmission occurs when germs are transferred from one infected person to another person without a contaminated intermediate object or person. Examples of direct transmission of infectious agents between patients and healthcare personnel include blood or other blood containing body fluids from an infected patient directly enter a caregiver's body through contact with a mucus membrane or breaks in the skin. Mites from a scabies-infested patient are transferred to the skin of a caregiver through direct, ungloved contact with the patient's skin. A healthcare provider develops a sore on a finger after contact with herpes simplyx virus when providing oral care to a patient without using gloves. Indirect transmission involves the transfer of an infection through a contaminated intermediate object or person. Respiratory droplets are generated when an infected person coughs, sneezes, or talks. Airborne transmission occurs by distribution of either airborne droplets or small particles which can be breathed in by another person. A person's skin prevents germs from entering into the body but if the skin is broken because of even a tiny cut it is possible for infected blood from another individual to enter.