The Spread of Infections
The spread of a communicable disease or infection involves the following components:
- A susceptible host
- A biological agent sufficient to cause disease
- A mode of transmission
All three must be present for an infection to spread from one person to another. This is called the “chain of infection”. An organism may have a single route of transmission, or it may be transmissible by two or more routes. If the chain is broken, the potential for infection is eliminated.
Modes of Transmission
Knowing the way by which disease or infection is transmitted is important in infection control.
The most common modes of transmission are through the following:
- Contact: In contact spread, the susceptible person has contact with the infected source and the contact is either direct, indirect, or by droplets.
- Direct Contact: This is where there is actual physical contact between the source and the susceptible person. The exposure is a result of close contact to skin and body secretions/fluids. Organisms can be transmitted from one part of the person’s body (such as their skin), to another part of their own body or another person (touching an open wound).
- Indirect Contact: This occurs when organisms from an infected host are transmitted to a susceptible host via an inanimate object. These sources can include medical equipment, clothing, toys, dressings, sinks, and so on.
- Droplet Transmission: Infectious agents in droplets are expelled from respiratory secretions by coughing, sneezing, or talking. Droplets are large particles that rapidly settle on horizontal surfaces or are deposited on a susceptible person’s nasal membranes or mouth. They cannot be transmitted beyond a radius of several feet from the source and require close contact with another person for transmission.
- Airborne Spread: Airborne describes organisms that have a true airborne phase in their route of dissemination. This usually results in a distance of more than several feet between the source and the receiver. Pathogens such as chickenpox and tuberculosis are transmitted in this way. This method of transmission may not require close contact with the infectious person.
- Host: Whether or not the microorganism infects a person depends on the ability of the organism to cause disease and the ability of the body to resist it. Previous exposure and immune response will also play a role. Disease does not always follow the transmission of infectious agents to the host.
Preventing the Spread of Infection
To prevent the spread of infection it is necessary to eliminate at least one of the three “chains of infection”. When working in a human service environment, taking the necessary precautions is the first step in preventing the spread of infection. Let’s look at an overview of common prevention strategies.
- Hand Washing: Hand washing is the number one method of infection control. Hands should be washed before and after all tasks involving occupational exposure to skin, and body fluids/secretions. If you work in an environment where you are shaking hands with multiple persons throughout the day, antiseptic towelettes or gel can be an infection control tool for staff members who do not have hand-washing facilities immediately available.
- Facility Cleanliness: Special care should be given to facility cleanliness. Bathrooms, lavatories, examination areas, work areas, and eating areas should be disinfected regularly with a fresh solution of one part household bleach to ten (10) parts water, or a commercial cleaning spray that is known to be a proven disinfectant. Employees in work areas with desks can easily be supplied with a commercial disinfectant cleaning spray and a roll of paper towels.
- Spills: All body fluid spills (regurgitation, diarrhea, urination, bleeding, sputum, etc.) should be cleaned promptly and the contaminated area disinfected. The area should be cleaned with a fresh solution of one (1) part bleach to ten (10) parts water. A spill kit should be maintained at all locations providing direct human services or contact, and in all vehicles used in the provision of transportation services.
- Waste Disposal: All items that contain semi-liquid blood or other bodily fluids, or items that would release blood or other infectious material if compressed (cleaning rags, tissues, dressings, gloves, gowns, masks, etc.) should be discarded in labeled biohazard red bags. These bags should be closed to prevent spillage or protrusion of contents during handling, transport, or shipping. In some instances, double bagging may be necessary. These bags should be coded with the regulated waste insignia and taken to a local hospital for appropriate disposal or removed from the premises by a contracted waste disposal provider.
- Barrier Protection: Gloves should be worn by any worker required to touch, or is susceptible to contact with blood and body fluids, mucous membranes, or non-intact skin. Gloves should be for single use only. Hands should be immediately washed after the gloves are removed.
- General Rules: Eating, drinking, smoking, applying cosmetics or lip balm, and handling contact lenses should not take place in areas where there is a reasonable likelihood of exposure to potentially infectious materials. Do not share glasses, cigarettes, or other items that could spread germs upon direct contact. If possible, avoid small, enclosed areas where close continual contact with others occurs. When not possible, be observant of persons in a small enclosure who may be coughing or display symptoms of airborne infections. Cover mouth when sneezing or coughing.