2.3 Identify common sources of infection

This guide will help you answer 2.3 Identify common sources of infection.

Understanding where infections come from helps to control their spread. In health and social care, this knowledge is basic. Infections can travel from people, places, objects, and even animals. Knowing the common sources supports safer care and protects people using services, staff, and visitors from getting ill.

What is an Infection Source?

A source of infection is where a germ begins its spread. Germs include bacteria, viruses, fungi, and parasites. These organisms can be tiny and invisible, but they can still cause illness. The source is often called the ‘reservoir’ because it holds and sometimes multiplies the germs.

People as a Source of Infection

Humans are the most common source of infection. People can carry germs on their skin, in their mouths, in cuts or open wounds, or in body fluids like blood and saliva. Sometimes a person is ill and it is obvious, but often people can carry germs without showing any symptoms. These people are called ‘carriers’. They might feel fine, but still pass on illness.

Some specific ways people spread infection are:

• Coughing and sneezing (which spreads droplets)
• Touching contaminated surfaces and then touching the face
• Not washing hands after using the toilet
• Caring for wounds or handling medical devices without proper hygiene

Body Fluids and Secretions

Many germs live in and are spread by body fluids. Key fluids that may hold germs are:

• Blood
• Saliva (spit)
• Mucus from the nose or mouth
• Urine
• Faeces (poo)
• Vomit
• Sweat

Handling these fluids needs care. Protective gloves, good hand washing, and the safe disposal of waste all help limit spread.

The Environment

Dirty environments can support germs. This means both healthcare environments and community settings, such as care homes, nurseries, or hospitals.

Common environmental sources of infection are:

• Contaminated surfaces like bed rails, tables, and door handles
• Dirty equipment and medical devices
• Unclean bathrooms and kitchens
• Poorly maintained ventilation and water systems

Germs can live for different amounts of time on surfaces. Some, like the bacteria that cause MRSA (Methicillin-resistant Staphylococcus aureus), can survive for days or even weeks on objects.

Food and Water

Improper food storage, handling, or preparation can result in foodborne infections. Water that is not clean, or comes from an unsafe source, can also carry germs.

Food and water may be contaminated by:

• Not washing hands before preparing food
• Undercooked meat or poultry
• Unpasteurised milk or dairy products
• Using the same chopping board for raw meat and vegetables
• Unclean water supplies

Such infections can cause upset stomachs, vomiting, diarrhoea, and worse. Examples of food and waterborne infections include salmonella, norovirus, and E. coli.

Air and Droplets

Air is a source for infections that spread through tiny droplets. When someone coughs, sneezes, talks, or breathes, droplets containing germs may travel through the air. People nearby can breathe in these droplets and get sick.

Common air and droplet spread infections are:

• Influenza (flu)
• Tuberculosis (TB)
• COVID-19
• The common cold

Good ventilation and respiratory hygiene (such as covering coughs and sneezes) can help.

Animals and Insects

Animals and insects sometimes carry infections that humans can catch. These are called zoonotic infections.

Animals can pass on germs through:

• Bites or scratches (e.g., rabies)
• Contact with animal waste (e.g., toxoplasmosis)
• Contaminated food (e.g., salmonella from undercooked eggs or poultry)
• Insects biting humans (e.g., ticks spreading Lyme disease, mosquitos spreading malaria)

People working with animals or outdoors are at higher risk. Workers should follow guidance about animal contact, especially around vulnerable people.

Healthcare Equipment

Medical and care equipment can become contaminated if it is not cleaned after each use. Items like thermometers, blood pressure cuffs, stethoscopes, hoists, or commodes can pass on germs.

Shared equipment needs cleaning between use with disinfectant. Disposable items should be thrown away after use with one person only.

Shared Personal Items

Items that touch the skin, mouth, or open wounds are high risk for passing on germs.

Examples include:

• Razors
• Toothbrushes
• Towels and washcloths
• Hairbrushes and combs
• Nail scissors or clippers

When people share these items, germs can move from one person to another. In care settings, personal items should only be used by one person.

Soil and Outdoor Sources

Some germs live in soil. They can enter the body through:

• Open cuts and wounds
• Eating food with soil on it (such as unwashed vegetables)
• Touching mouth or nose with dirty hands after gardening

Examples include the bacteria that cause tetanus. Wearing gloves for gardening and cleaning cuts promptly can reduce risk.

Hand Contact

Hands are one of the main ways germs travel from one place or person to another. Germs can move from hands to surfaces, objects, or people.

Common situations where hands become contaminated:

• After using the toilet
• After handling money
• Before preparing food
• After blowing one’s nose
• After dealing with pets or cleaning waste

Hand washing is an effective way to cut down infection spread in all care settings.

Linen and Laundry

Used bedclothes and towels can be a source of infection. This is particularly true if they are soiled with body fluids.

Examples:

• Bedpans or sheets with blood or faeces
• Towels used in personal care like washing or drying an open wound

Staff should use gloves, bag soiled laundry, and wash it at the correct temperature.

Waste and Refuse

Care settings create lots of waste, including used dressings, needles, tissues, and nappies. If not dealt with properly, this waste can become an infection source.

Safe waste disposal involves:

• Using the right bins for different types of rubbish
• Wearing gloves when handling waste
• Following local protocols for clinical, hazardous, and regular waste

Common Germs and Their Typical Sources

Different germs prefer different environments. Here are a few examples:

• Norovirus (stomach bug): Spread through contaminated food, water, and surfaces. Outbreaks are common in care homes and hospitals.
• MRSA: Lives on skin and on surfaces, and can enter the body through wounds or devices.
• Clostridioides difficile (C. diff): Grows in the gut, but spores can survive on surfaces for long periods.
• Influenza and COVID-19: Spread by coughing, sneezing, and talking—tiny droplets stay in the air or fall on objects.
• Salmonella: Contaminates undercooked poultry, eggs, and some fruit and vegetables.

How to Recognise Potential Infection Sources

Not all sources are visible. Some risks are hidden or hard to spot. Paying attention to hygiene and standard safety procedures protects everyone.

Key signs that something may be a source:

• It is touched by lots of people (e.g., door handles)
• It looks dirty or soiled
• It is damp or contains food waste, blood, or body fluids
• It smells bad

When in doubt, treat it as if it could spread infection, and act to clean or isolate it.

Preventing Spread from Common Sources

Prevention is better than treatment. Simple steps make a big difference in controlling the pressures infections put on care services.

Prevention steps involve:

• Regular, thorough hand washing
• Cleaning surfaces and equipment after each use
• Wearing gloves and other protective clothing when in contact with body fluids or waste
• Using single-use or personal items for each person
• Proper food storage and preparation methods
• Safe handling and washing of laundry
• Good ventilation of indoor spaces

Reporting and Acting on Infection Risks

Staff must notice risks and report them straight away. If you spot dirty equipment, soiled linen, poor waste storage, pest problems, or someone with diarrhoea, fever, or spots, you should tell your manager.

Prompt action helps reduce risk to everyone.

Training and Awareness

Ongoing learning about infection sources keeps everyone safe. Your workplace may provide regular training, updates, posters, and written policies. You need to know:

• What types of infections and sources are most likely in your setting
• Who are the most vulnerable people in your care
• Where to find equipment and supplies for cleaning and protection
• How to report concerns

Professional Practice: Policy and Law

Some legal frameworks guide action on infection. Key laws and standards include:

• The Health and Social Care Act 2008 (Regulated Activities) Regulations 2014
• Control of Substances Hazardous to Health (COSHH) Regulations 2002
• Food Safety Act 1990
• Infection control policies specific to your workplace

Failure to follow these can result in investigations, enforcement actions, or harm to people.

Final Thoughts

Awareness of infection sources is your first step in stopping and slowing the spread. Notice your environment, look for risks and act straight away. Small steps—like washing your hands, cleaning equipment, and dealing with waste correctly—save lives.

Keep up to date with your workplace’s procedures. This protects the people in your care, your colleagues, your own health, and the reputation of the service. If unsure, always ask or review local guidance—better safe now than sorry later.