2.4 Explain how infective agents can be transmitted to a person

This. guide will help you answer 2.4 Explain how infective agents can be transmitted to a person.

Infective agents are tiny living organisms that can cause disease. These include bacteria, viruses, fungi, and parasites. You can sometimes see signs of their presence, like mould on bread (caused by a type of fungus), but the agents themselves are microscopic.

Each type of infective agent has different properties. Some survive on surfaces for hours or days. Others need to enter the body quickly to survive. Awareness of these characteristics helps prevent the spread of infection.

In a health and social care setting, you will come across terms such as ‘pathogen’ and ‘host’. A pathogen is another word for an infective agent. The ‘host’ is the person, animal, or sometimes object that the agent lives on or in.

The Main Routes of Transmission

Transmission means how infective agents spread from one person, animal, or object to another person. There are several main ways this can happen:

• Direct contact
• Indirect contact
• Droplet spread
• Airborne spread
• Bloodborne spread
• Food and waterborne spread
• Vector-borne spread (from animals or insects)

Understanding these different routes is the foundation for infection control. Below, each method is explained in detail with clear examples from care settings.

Direct Contact Transmission

Direct contact happens when the infective agent passes directly from an infected person to someone else. This can be through physical touch, such as:

• Touching someone’s skin
• Hugging
• Kissing
• Handshakes

In a care setting, direct contact includes helping a service user with personal care, such as bathing or dressing wounds. Some infections, like scabies, transfer easily through skin-to-skin contact.

Bodily fluids (such as blood, saliva, or other secretions) can also lead to direct transfer of infective agents. For example, if a staff member does not wear gloves while caring for an open wound, bacteria or viruses may transfer straight into their skin or any open cuts.

Indirect Contact Transmission

Indirect contact involves an infective agent being passed from person to person via another object or surface, known as a ‘fomite’. Fomites include items like:

• Door handles
• Bed rails
• Medical equipment
• Phones or tablets
• Shared towels

When a person touches a contaminated object and then touches their eyes, mouth, or any open area of skin, the pathogen can enter the body. For example, the bacteria that cause MRSA can live on surfaces for some time. If hands are not washed after touching a contaminated item, the bacteria may be transferred.

Droplet Transmission

Some infective agents are spread through droplets released when an infected person:

• Coughs
• Sneezes
• Talks loudly
• Sings

The droplets do not stay in the air for long. They can travel around one metre before falling onto surfaces or entering another person’s mouth, nose, or eyes.

Flu and some forms of coronavirus (such as COVID-19) are commonly spread in this way. In a care home, if a service user with a cold sneezes near another person, the virus can enter the second person’s respiratory tract and cause infection.

Wearing masks, covering coughs with tissues, and keeping a safe distance help stop droplet transmission.

Airborne Transmission

Infective agents that cause airborne transmission are contained in much smaller particles than those found in droplets. These microscopic particles can stay suspended in the air for long periods and travel further distances.

Diseases that may be spread this way include:

• Tuberculosis
• Chickenpox
• Measles

Unlike droplet transmission, these infective agents can be inhaled by people who have not had direct contact with the infected individual. Poor ventilation, particularly in indoor spaces, increases the risk.

In health and social care environments, airborne spread is a concern when caring for people with these diseases. Staff may use special masks (such as FFP3 respirators), and keep affected people in isolation rooms.

Bloodborne Transmission

Some infective agents are present in blood and certain other bodily fluids. Transmission can occur if:

• Blood from an infected person enters another person’s bloodstream through a scrape or cut
• Needlestick injuries occur (being accidentally pricked by a used needle)
• People share personal items such as razors or toothbrushes that have traces of blood on them

Bloodborne viruses include:

• Hepatitis B
• Hepatitis C
• HIV (Human Immunodeficiency Virus)

Strict procedures are followed when dealing with spills of blood. Healthcare workers wear gloves, masks, and sometimes goggles to avoid exposure. Used needles and other sharp items are thrown away immediately in yellow bins called ‘sharps boxes’.

Food and Waterborne Transmission

Infective agents can grow in food or water. If a person eats or drinks something contaminated, the agent enters their digestive system.

Common causes include:

• Improperly cooked meat or poultry
• Unwashed fruits or vegetables
• Drinking water contaminated with sewage
• Poor food storage

Nausea, vomiting, diarrhoea, and stomach cramps are common symptoms of food or waterborne infections. Some common pathogens that spread this way are Salmonella and Norovirus.

Care workers help to prevent these infections by following strict hygiene procedures, such as washing hands before preparing food and keeping food at safe temperatures.

Vector-Borne Transmission

Vectors are living creatures that can carry and transfer infective agents to humans or between humans. The most common examples are insects and animals.

Some key vectors are:

• Mosquitoes (carry malaria and Zika virus)
• Ticks (carry Lyme disease)
• Fleas (can spread plague)

While vector-borne diseases are more common in other countries, they can still present risks in the UK. For example, tick bites can pass on Lyme disease, especially in rural or woodland areas.

Breaks in the Skin and Mucous Membranes

Your skin usually acts as a strong barrier against infective agents. Any break—such as a cut, graze, or burn—can provide a way in.

The mucous membranes lining the mouth, nose, eyes, and genital areas are softer and easier for infective agents to enter. These areas may become exposed if a person touches their face with dirty hands or if contaminated droplets land there.

Staff are advised to keep their own minor wounds covered at work and to report any major injuries or exposures straight away.

Hand-to-Face Transfer

A common way infective agents enter the body is when people touch contaminated surfaces or objects and then touch their own face. The mouth, eyes, and nose are all ‘entry points’. Infections such as the common cold are easily spread this way.

Regular, thorough hand washing is the most effective way to reduce hand-to-face transfer of infective agents.

Use of Personal Protective Equipment (PPE)

Using PPE—such as gloves, masks, gowns or aprons, and goggles—is a key control measure in many health and social care tasks. PPE acts as a barrier and reduces the chances of infective agents passing from person to person or from surfaces to workers.

Correct use of PPE, including safe removal and disposal, prevents infection incidents which result from spills and splashes.

Poor Hygiene Practices

Lack of hand washing, not cleaning equipment thoroughly, or failing to dispose of waste properly, can all lead to transmission of infective agents.

Examples in care settings:

• Using the same gloves for tasks with different people
• Not washing hands between every care task
• Using re-usable cloths that are not washed or changed regularly

Every worker must follow hygiene policies and procedures. This action protects not only service users but staff themselves.

The Chain of Infection

The ‘chain of infection’ describes how an infection can pass from its source to a new person. This happens in six basic steps:

1. Infective agent (such as bacteria or virus)
2. Reservoir (where it lives: people, animals, food, water, or objects)
3. Portal of exit (how it leaves the reservoir: through sneezes, wounds, faeces, saliva, etc.)
4. Mode of transmission (route: hands, surfaces, air, blood, water, food, insects or animals)
5. Portal of entry (how it gets into the new person: mouth, nose, broken skin, etc.)
6. Susceptible host (a person who has little or no immunity)

Breaking any link in this chain will help prevent infective agents from reaching and infecting new people.

Examples in Health and Social Care

Scenarios in Everyday Practice:

• A care worker changes a dressing on an infected wound and touches a table without washing hands. Another person touches the table and then rubs their eye, leading to possible infection.
• Two service users share a bathroom. One has diarrhoea from a contagious stomach bug. The bathroom is not cleaned between uses, so the second person is exposed via contaminated surfaces.
• During an outbreak of flu, a staff member with mild symptoms coughs while supporting a vulnerable person. The infected droplets land on the person, who later develops symptoms.

Summary of Key Prevention Strategies

Understanding how infective agents are transmitted supports safer working. Main methods to interrupt transmission include:

• Washing hands frequently and correctly
• Using disposable gloves and aprons for personal care tasks
• Keeping wounds covered
• Following safe practice when handling food and drink
• Cleaning and disinfecting surfaces and equipment
• Disposing of waste such as dressings, needles, or unused food correctly
• Keeping up-to-date with training on infection prevention

Reflective Practice

Ask yourself during your work:

• How could infective agents be spread in this situation?
• What steps am I taking to reduce risks?
• Are there any gaps in my practice, such as forgetting to change gloves, or missing out on hand hygiene?

Regular reflection helps reduce spread in a care setting.

Final Thoughts

Infective agents can be transmitted through a wide range of routes—some easy to see, some hidden. Prevention means action: good hand washing, safe use of PPE, keeping equipment clean, and following procedures. You make a difference every day by stopping the spread. Your understanding and vigilance will protect service users, colleagues, and yourself.

Keep these transmission routes in mind during tasks, and always practice good hygiene, awareness, and reporting. If in doubt, discuss questions or incidents with your supervisor straight away. Your actions matter.