An inanimate object that becomes contaminated with infectious agents and transfers them to a new host is called a fomite. These objects act as passive vectors for pathogens like bacteria, viruses, and fungi. Contamination occurs when a fomite contacts bodily fluids or particles from a cough or sneeze. The fomite then holds the pathogen until a person touches it, creating an opportunity for infection through indirect contact transmission.
Common Fomites in Everyday Life
Fomites are present in every environment, from private homes to public spaces and healthcare facilities. In a home, frequently touched items like television remotes, kitchen sponges, countertops, and doorknobs can harbor germs. These objects are handled by multiple people, allowing for the transfer of infectious agents between family members.
Public areas are filled with shared surfaces that can function as fomites, such as shopping cart handles, elevator buttons, and ATM keypads. In these high-traffic locations, a single contaminated object can be touched by many people in a short period. This increases the chances for widespread exposure to any pathogens on the surface.
Clinical settings have a high concentration of fomites due to patient care. Objects like stethoscopes, blood pressure cuffs, and bed rails are used with multiple patients and can become contaminated. Even non-medical items in hospitals, like computer mice at nursing stations or waiting room chairs, can serve as reservoirs for pathogens.
Pathogen Survival on Surfaces
The duration that a pathogen can remain viable on a fomite depends on several factors. The specific type of microbe is a primary determinant. For example, norovirus is resilient and can survive on surfaces for days or weeks, whereas the influenza virus is less durable, often lasting for about 24 hours on hard surfaces.
The characteristics of the surface material also play a role. Non-porous surfaces like stainless steel and plastic allow viruses and bacteria to survive longer than porous surfaces such as fabric or wood. Porous materials can absorb moisture, which may inactivate some pathogens more quickly, but they are also harder to clean thoroughly.
Environmental conditions also influence pathogen longevity. Higher humidity can extend the survival time for many viruses, while direct exposure to ultraviolet (UV) light from the sun can inactivate them. Temperature also affects survival, as many pathogens fare better in cooler, indoor environments.
Fomite Transmission and Prevention
The spread of disease through fomites is a two-step event. First, a person must touch a contaminated object. The second step involves that person touching a mucous membrane—the eyes, nose, or mouth—with their now-contaminated hand. This self-inoculation introduces the pathogen into the body where it can cause illness.
Interrupting this chain of transmission involves managing both surfaces and personal actions. There is a distinction between cleaning and disinfecting. Cleaning is the physical removal of dirt and some germs from a surface with soap and water. Disinfection uses chemicals to kill the pathogens that remain after cleaning.
The most effective way to prevent fomite transmission is consistent hand hygiene. Washing hands with soap and water for at least 20 seconds or using an alcohol-based hand sanitizer can remove or inactivate pathogens. This action breaks the chain of infection by removing germs from your hands before they have a chance to enter your body.