The chain of infection is a model used to understand how infections spread and how they can be prevented. It consists of six components, which are as follows:
- Infectious agent: This is the microorganism that causes disease, such as a virus, parasite, fungus, or bacterium.
- Reservoir: This refers to the environment or habitat where the pathogen can live and multiply. It includes environmental surfaces, body fluids, food, water, soil, and the respiratory tract.
- Portal of exit: This is the way the pathogen leaves the reservoir, such as through the skin, blood, mucous membranes, or oral cavity.
- Mode of transmission: This describes how the pathogen moves from the reservoir to a susceptible host. It can be through direct transmission (e.g., airborne, droplet, contact) or indirect transmission (e.g., fomites, vectors, food, water) .
- Portal of entry: This is the opening where the pathogen may enter the host, such as body openings, incisions, or wounds.
- Susceptible host: This refers to the person at risk of being infected, and factors affecting susceptibility include age, health, co-morbidities, immune system, nutrition, infective dose, and medications.
To prevent the spread of infection, it is essential to break the chain of infection at any of these six links. This can be achieved through measures such as hand hygiene, vaccination, covering coughs and sneezes, using personal protective equipment, cleaning and disinfecting the environment, sterilizing medical instruments, following safe injection practices, and using antibiotics wisely. By interrupting the chain of infection, the spread of germs can be stopped, ultimately preventing infections from occurring and spreading further.
