Infection Control and How Infections Spread

Infection Control

The term "Infection Control" refers to protection against hospital-acquired infections or, in other words, controlling infections within healthcare services. It is one of the most critical topics for healthcare workers because of the negative impact it leaves on those exposed to it. Infection can be transmitted from a patient to any hospital staff member or to other patients. Therefore, the term "Infection Control" is constantly repeated to protect against infectious diseases. It is essential to implement infection control to limit its spread among patients, visitors, hospital staff, or the external environment. A hospital is a place where all segments of society interact; it is the "house of disease" that can spread infection outside its walls. Thus, great attention must be paid to applying infection control methods to curb the spread of infection"".

Modes of Infection Transmission

Infection does not occur without the presence of the essential elements leading to it. These elements are an infectious agent, a source for this agent, and a susceptible host. Most importantly, there must be a method by which the agent is transmitted from the source to the host. The interaction between all these elements is known as the "Chain of Infection" or the "Disease Transmission Cycle," and this interaction focuses on the links and relationships between all these elements"".

Components of the Disease Transmission Cycle

1- Infectious Agents: These are the microbes that can cause infection or disease, including bacteria, germs, viruses, fungi, and parasites.

2- Infectious Reservoir: This is the place where disease-causing microbes live, grow, and multiply. It could be in humans, animals, plants, soil, air, water, or other solutions, tools, and equipment used in hospitals that may act as a reservoir for disease-causing microbes.

3- Exit Portals: This refers to the path through which the infectious agents exit. The infectious organism can leave the reservoir through the bloodstream or openings in the skin, such as superficial or deep wounds, surgical sites, and skin rashes. It also includes mucous membranes like the eyes, nose, and mouth; the respiratory system like the lungs; the urinary and reproductive tracts; the digestive system like the mouth and anus; or the placenta, via blood, secretions, or droplets coming from these parts of the body.

4- Modes of Transmission: This refers to the method by which microbes travel from the reservoir to the susceptible host. There are several ways infectious agents are transmitted, such as:

- Contact: The infectious organism may be transmitted directly from the reservoir to the susceptible host through touch. Examples include Staphylococci bacteria and sexual relations such as Gonorrhea or HIV. Contact is considered the most important and common mode of infection transmission and can be divided into two types:

(1) Direct Contact: Refers to the transmission of microbes resulting from the touch of an infected person's body surface with the body surface of another person susceptible to the disease.

(2) Indirect Contact: Refers to the susceptible person's contact with a contaminated material such as medical equipment, needles, bandages, the contaminated hands of healthcare providers, or contaminated gloves that were not replaced when dealing with patients.

- Droplet Transmission: Refers to the transmission of disease-causing microbes through droplets containing microbes produced by the source of infection while speaking, sneezing, or coughing, or resulting from certain medical procedures like bronchoscopy or respiratory suctioning devices. These droplets enter the host's body through the mouth, nasal mucosa, or the eyes (conjunctiva). Droplets are characterized by a density that does not allow them to remain suspended in the air, meaning that microbes transmitted via droplets are different from those in the air; therefore, there is no need for special ventilation techniques to prevent transmission through this path.

- Airborne Transmission: Infectious agents may be transmitted via very small droplet nuclei, less than or equal to 5 microns, containing microorganisms that remain suspended in the air, carrying them over long distances unlike large droplets. The susceptible host then inhales these small nuclei, such as Measles and Tuberculosis. These small nuclei remain suspended in the air for varying periods, and here, the use of good ventilation methods is beneficial in preventing microbe transmission.

- Vehicle Transmission: Infectious microbes may be transmitted indirectly to the host through a substance contaminated with the infectious agent. These vehicles include food, such as Salmonella; blood, such as Hepatitis B, Hepatitis C, and HIV; water, such as Cholera; and contaminated tools, for example, with Hepatitis B, Hepatitis C, or HIV/AIDS.

5- Portals of Entry:

Portals of entry represent the path that disease-causing microbes take to enter the susceptible host's body. These microbes may enter through:

• - The bloodstream (through device entry sites such as intravenous catheters and syringes)
• - Skin openings (e.g., superficial and deep wounds, skin rashes, and surgical sites)
• - Mucous membranes (e.g., eyes, nose, and mouth)
• - The respiratory system (e.g., lungs)
• - Urinary and reproductive tracts (e.g., vagina and penis)
• - The digestive system (e.g., mouth and anus)
• - The placenta

6- Susceptible Host: This is the person who can be infected by disease-causing microbes. This host could be the patient, a healthcare worker, hospital assistants, visitors, or other members of society. The host varies depending on the infectious agent, and vaccination against certain types of infectious microbes helps reduce infections caused by these microbes.

See also: Infection Control and Prevention of Infection in Hospitals