Early on at Stonehill Community Clinic, you learn that staff members occasionally do presentations for their colleagues on various relevant topics. Your supervisor asks you to put together a training on the chain of infection and all the links involved.

describe the six links in the chain of infection as if you were presenting to members of your medical team. Be sure to identify at least three ways in which you could break—or interrupt—the chain of infection.

The six links in the chain of infection are the following:

1 Infectious agent or pathogen - The first link in the chain of infection which can take the form of:

• Viruses (influenza A, shingles, hepatitis)
• Bacteria (Lyme disease, leptospirosis)
• Fungi (candidiasis, aspergillosis)
• Parasitic protozoan diseases (malaria, giardiasis and toxoplasmosis)
• Prions (Creutzfeldt-Jakob disease)

The pathogen is able to thrive depending on its pathogenicity (ability to produce disease), degree of virulence (severity or harmfulness), and invasiveness (tendency to spread).

2 Reservoir - The principal habitat in which a pathogen lives, flourishes and is able to multiply. Common reservoirs for infectious agents are the following:

• Human reservoirs -  There are two forms which include acute clinical cases (someone is infected and displaying signs and symptoms of the disease) and carriers (someone has been colonized with an infectious agent but is not unwell).
• Animal and insect reservoirs - Lyme disease (ticks), rabies (dogs, cats, foxes, and bats), and salmonella (poultry, cattle, sheep and pigs).
• Environmental reservoirs - Soil (Clostridium tetani, causative agent of tetanus) and water (Legionella pneumophila, the causative agent of Legionnaire's disease).

3 Portal of exit - Any route the infectious agent or pathogen leaves the reservoir. The key portals of exit in humans are:

• Alimentary (vomiting, diarrhea, biting)
• Genitourinary (sexual transmission)
• Respiratory (coughing, sneezing, talking)
• Skin - (skin lesions)
• Transplacental - (mother to fetus)

4 Mode of transmission -  The way infectious agent or pathogen can be passed on from its reservoir to a susceptible host. The two main ways it can be transmitted are:

• Direct transmission - Immediate and occurs when there is direct contact with the infectious agent (e.g. tetanus, glandular fever, respiratory diseases, sexually transmitted diseases).
• Indirect transmission - Occurs through animate mechanisms (fleas, ticks, flies, mosquitoes) or inanimate mechanisms (food, water, biological products, surgical instruments). It can also be airborne where tiny particles of an infectious agent/pathogen are carried by dust or droplets in the air and inhaled into the lungs.

5 Portal of entry - The way the infectious agent or pathogen is able to enter a susceptible host. The portals of entry into the human body include:

• Inhalation (respiratory tract)
• Absorption (mucous membranes)
• Ingestion (gastrointestinal tract)
• Inoculation (result of inoculation injury)
• Introduction (insertion of medical devices)

6 Susceptible host - The last link in the chain of infection which can be any person. The susceptibility of the host depends on the following:

• Age (very young or very old)
• Presence of malnutrition or dehydration
• Underlying chronic disease
• Presence of invasive medical devices (lines, devices, airways)
• Taking of medications which could suppress immune response
• General resistance factors (mucous membranes, skin, cough reflex, etc.) that aids in defending against infection.

The ways to break or interrupt the chain of infection are the following:

• Proper hand washing, covering mouth and nose when coughing and sneezing, staying home when sick, and updated on vaccines.
• Rapid and accurate diagnosis of an infectious disease as well as prompt treatment of infected patients.
• Safe disposal of waste, following safe injection practices, sterilizing medical instruments and equipment, and implementation of an environmental decontamination strategy.