Skip to main content
Medicine LibreTexts

12.2.1: Chain of Infection

  1. Last updated
  2. Save as PDF
  • Page ID
    67704

    • Erin O'Hara-Leslie, Amdra C. Wade, Kimberly B. McLain, SUNY Broome
    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    The chain of infection is how infection is transmitted (passed). The chain of infection consists of five parts: reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host.

    1. Reservoir: A reservoir is the same thing as a host. Reservoirs include humans, animals, and the environment, such as water or soil. This is the person, animal, or place where the infectious agent lives and grows (CDC, 2012).

    2. Portal of exit: This is how the infectious agent leaves its host (CDC, 2012). Portals of exit can include the respiratory system, urine, feces, and even the skin. For example, if a person has influenza (the flu), they can transmit the virus to another person when they sneeze. If a person has hepatitis B or HIV, they can transmit the virus through their blood or body secretions.

    3. Mode of transmission: This is how an infectious agent is transmitted (or given) to a person. There are several modes of transmission: direct contact, droplets, airborne, vehicles, and vectors (CDC, 2012).

    • Direct Transmission: Infectious agents are transmitted either through direct contact with a reservoir (host) or by droplet transmission.
      • Direct Contact: Transmission this way occurs through direct skin to skin contact, sexual intercourse, and exchange of body fluids such as while kissing. Mononucleosis, Hepatitis B, and HIV are spread via direct contact (CDC, 2012).
      • Droplets: Transmission this way occurs when droplets from sneezing, coughing, or talking are spread a few feet onto another person. Pertussis and meningococcal infections are spread via droplets (CDC, 2012).
    • Indirect Transmission: Infectious agents are transmitted from a reservoir to a host through airborne droplets, inanimate objects (vehicles), or animate intermediaries (vectors) (CDC, 2012).
      • Airborne: Transmission this way occurs when droplets remain suspended in air and eventually contaminate a susceptible host. Measles is an example of an infection that is spread by airborne transmission (CDC, 2012).
      • Vehicles: Transmission by vehicles occurs through blood, water, food, and fomites (objects such as surgical instruments, used tissues, and dirty bedding). Hepatitis A is transmitted through a vehicle as it is carried through food or water that has been contaminated; botulism is spread via a vehicle as the bacteria are found in contaminated canned food (CDC, 2012).
      • Vectors: Transmission via vectors occurs through ticks, mosquitoes, and fleas. Malaria is transmitted through mosquitoes (a vector); Lyme’s Disease is transmitted through ticks (a vector) (CDC, 2012).

    4. Portal of entry: This is how the infectious agent enters the host or person (CDC, 2012). The portal of entry is often the same as the portal of exit. For example, influenza exits an infected person’s respiratory tract and enters another person’s respiratory tract (CDC, 2012).

    5. Susceptible host: The susceptible host is the person or animal who contracts the infectious disease. The very young and the elderly are most at risk for contracting an infection. The immune system is not fully developed in a young child. As we age, our immune system is no longer as effective as it was when we are young. People who are already sick or immunocompromised (who have an immune system that is unable to fight infection) are at high risk for becoming a susceptible host.

    Home Health Aides/Personal Care Aides have an important role in breaking the chain of infection. By properly washing hands, wearing gloves when coming into contact with body fluids and blood, and properly cleaning and sanitizing equipment and the home, HHAs/PCAs can help stop the chain of infection. Other ways that HHAs/PCAs can help break the chain of infection include teaching patients to sneeze or cough into a tissue and then immediately wash their hands. Teaching patients to practice proper hand hygiene before meals, after using the bathroom, and anytime hands become soiled is another important way HHAs/PCAs can help stop the chain of infection.

    HHAs/PCAs should also teach patients to place used sharps from needles in designated sharps containers. Used needles should never be disposed of in the garbage or left out. This puts others at risk for contracting an infectious disease. Disposal of sharps containers will vary depending on where the HHA/PCA lives. This is an important issue that should be discussed with a supervisor.

    Handwashing is the number one way to prevent the spread of infection. Hands should be washed when they are visibly dirty or soiled with blood, body fluids, and secretions. Hands should be washed before and after eating and using the restroom. Hands should be washed when arriving at and before leaving the patient’s home. Wash your hands before putting on gloves and after removing them. Wash your hands before and after all patient contact, including contact with the patient’s belongings.

    When Home Health Aides/Personal Care Aides care for patients, they should always practice proper hand hygiene and use personal protective equipment (PPE). This includes the use of gloves. Gloves should be worn anytime the HHA/PCA will come into contact with blood or body fluids, such as urine, feces, or vomit. Gloves should always be changed when they are visibly soiled or ripped.

    The following procedures will discuss proper handwashing, Donning and doffing of gloves.

    This page titled 12.2.1: Chain of Infection is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Erin O'Hara-Leslie, Amdra C. Wade, Kimberly B. McLain, SUNY Broome (OpenSUNY) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.