1.2 Identify common illnesses and infections caused by bacteria, viruses, fungi and parasites

This guide will help you answer 1.2 Identify common illnesses and infections caused by bacteria, viruses, fungi and parasites.

Everyday contact in health and social care brings people into close proximity. Infectious illnesses pose frequent risks to both workers and people receiving care. These illnesses come from several sources, with the most common being bacteria, viruses, fungi, and parasites. Each group includes infections with traits unique to their cause. Spotting these differences helps recognise illnesses early, reduces risk, and supports better outcomes.

This guide covers these causes with examples for each group.

Bacterial Illnesses and Infections

Bacteria are single-celled organisms too small to see with the eye. Some bacteria help the body, but others cause harm and disease. Bacterial infections remain leading causes of illness in healthcare and the community.

Key Features

• Bacteria can live on the skin, in the gut, or in the environment.
• Harmful bacteria can spread through touch, food, contaminated surfaces, breathing in droplets, or by wounds.
• These infections often respond well to antibiotics, though resistance is now common.

Common Illnesses Caused by Bacteria

1. Urinary Tract Infection (UTI)
This happens when bacteria, mostly Escherichia coli (E. coli), get into the urinary system. Symptoms include pain when urinating, passing urine more often, fever, and lower abdominal pain. UTIs are common in older people and those with catheters.

2. Tuberculosis (TB)
TB results from infection with Mycobacterium tuberculosis. It often affects the lungs, causing a long-lasting cough, chest pain, coughing up blood, fever, and weight loss. TB spreads when someone breathes in droplets from an infected person who coughs or sneezes.

3. Wound Infections
Cuts, surgical sites, or pressure sores can get infected with bacteria such as Staphylococcus aureus or Streptococcus pyogenes. Signs include redness, swelling, pain, pus, and sometimes fever.

4. Pneumonia
Bacterial pneumonia often results from Streptococcus pneumoniae, leading to cough, chest pain, fever, and breathlessness. It is a risk for older people, those with lung disease, and after surgery.

5. Gastroenteritis
This stomach and bowel infection can be caused by bacteria such as Salmonella, Campylobacter, or E. coli. Main symptoms are diarrhoea, stomach cramps, nausea, vomiting, and sometimes fever.

Key Actions in Practice:

• Wash hands thoroughly after contact with body fluids or contaminated items.
• Clean wounds and dressings using sterile techniques.
• Use personal protective equipment (PPE) if there’s a risk of contact with blood or body fluids.
• Follow infection control policies, especially for vulnerable people.

Viral Illnesses and Infections

Viruses are much smaller than bacteria and cannot reproduce alone—they need to invade living cells. Viruses cause a wide range of illnesses, from minor colds to severe long-term health problems.

Key Features

• Viruses spread through touch, the air, food, water, or direct contact with body fluids.
• Antibiotics do not work against viruses. Vaccines may prevent some viral infections.
• Illnesses range in severity and often spread quickly.

Common Illnesses Caused by Viruses

1. Influenza (Flu)
The flu is highly contagious. Symptoms include fever, chills, muscle aches, cough, sore throat, and fatigue. It spreads through respiratory droplets after sneezing or coughing.

2. Common Cold
Usually triggered by a group of viruses called rhinoviruses. Causes runny nose, sore throat, sneezing, mild cough, headache, and sometimes slight fever.

3. Norovirus
Known as the ‘winter vomiting bug’. Leads to sudden vomiting and diarrhoea. Norovirus spreads easily where people live closely together, such as care homes.

4. Hepatitis B and C
These affect the liver and spread through blood (often by needlestick injuries) and sexual contact. Symptoms can include tiredness, joint pain, and yellow skin or eyes (jaundice), though some have few symptoms at first.

5. HIV (Human Immunodeficiency Virus)
HIV attacks the immune system and passes through blood, sexual fluids, or mother to baby. Without treatment, it leads to AIDS, but with lifelong medication, people can remain healthy for many years.

6. Chickenpox and Shingles
Caused by varicella-zoster virus. Chickenpox gives an itchy rash with blisters. Later in life, the same virus can cause shingles—a painful, blistering rash usually on one side of the body.

Key Actions in Practice:

• Promote and support vaccination.
• Stay off work when infectious, if possible.
• Remind all visitors and staff to use tissues when sneezing or coughing—catch it, bin it, kill it.
• Follow procedures for safe cleaning and waste disposal.
• Use gloves and aprons if there’s a risk of coming into contact with body fluids.

Fungal Illnesses and Infections

Fungi include moulds and yeasts. They live in the environment and sometimes on the body. Most are harmless, but some can cause illness, especially in people with weak immune systems.

Key Features

• Fungal infections can affect the skin, nails, mouth, or lungs.
• These infections often spread through direct contact or by sharing towels, shoes, or surfaces.
• Certain antibiotics and illnesses increase risk.

Common Illnesses Caused by Fungi

1. Athlete’s Foot (Tinea Pedis)
Affects the skin between toes or on the feet. Skin appears flaky, itchy, sometimes blistered, and may split. Often caught in warm, damp places, like communal showers.

2. Ringworm (Tinea Corporis)
Despite its name, this is not a worm but a fungal infection. It forms a red, circular rash with clearer skin in the centre. Can appear anywhere on the body and spreads by touching the infected area, surfaces, or pet fur.

3. Thrush (Candidiasis)
This infection is caused by Candida yeast. It can affect the mouth (oral thrush) or the genital area. In the mouth, it appears as white patches; on skin, the area looks sore and red. Thrush arises if normal body balances are disturbed, such as after antibiotics.

4. Fungal Nail Infection (Onychomycosis)
Nails become thickened, discoloured, and may break easily. More common in toes. Poor foot hygiene and existing skin infections increase risk.

5. Invasive Fungal Infections
These are rare but serious, mostly affecting people with poor immunity. Examples include invasive aspergillosis, which attacks the lungs.

Key Actions in Practice:

• Keep skin clean and dry, paying special attention to feet and body folds.
• Help people avoid sharing towels, shoes, or nail equipment.
• Advise on prompt treatment for athletes’ foot or other rashes.
• Support high standards of cleaning, especially in shared bathrooms and showers.

Parasitic Illnesses and Infections

Parasites are living organisms needing a host—the body of another living thing—to live or feed on. Some cause only minor problems, but others can lead to chronic, serious illnesses. Parasites may be insects or tiny organisms.

Key Features

• Parasites live in or on the human body. Some are visible to the eye; others are microscopic.
• They spread through person-to-person contact, contaminated food or water, insect bites, or by touching affected surfaces.

Common Illnesses Caused by Parasites

1. Head Lice
Small insects live on the scalp or hair. Lice cause itching and irritation. They spread through close head-to-head contact, commonly among children.

2. Scabies
A tiny mite called Sarcoptes scabiei burrows into the skin. Causes intense itching, especially at night, and a rash with small blisters or sores, often between the fingers or wrists. Easily passed by skin contact or by sharing bedding or clothes.

3. Threadworm (Pinworm)
Common in children. Tiny thread-like worms live in the bowel. Main symptom is itching around the anus, usually at night. The eggs can spread easily, leading to reinfection.

4. Malaria
Spread by bites from infected mosquitoes. Not common in the UK but very important for travellers. Symptoms include fever, headache, and muscle pain. Malaria can cause serious illness if not treated quickly.

5. Toxoplasmosis
Caused by the Toxoplasma gondii parasite, often found in cat faeces or undercooked meat. In healthy adults, it seldom causes symptoms. In unborn babies and people with poor immunity, it can cause serious problems.

Key Actions in Practice:

• Regularly check for signs of lice, especially in groups such as children or care home residents.
• Advise people not to share hairbrushes, hats, or bedding.
• Promote good hand hygiene, especially before meals and after using the toilet.
• Support families and clients to clean bedding and clothing if an outbreak occurs.

Summary Table

Here’s a table highlighting common examples from each group:

Type	Common Illness	Main Cause	Typical Symptoms
Bacteria	UTI, Pneumonia, TB	E. coli, S. pneumoniae	Fever, pain, cough
Virus	Flu, Cold, Norovirus	Influenza virus, Norovirus	Cough, runny nose, sickness
Fungi	Athlete’s foot, Thrush	Trichophyton, Candida	Itching, rash, white patches
Parasite	Head lice, Scabies	Lice, scabies mite	Itching, rash

Preventing Infection Spread

Recognising the source of an infection helps you follow the right precautions. By using protective equipment, keeping shared areas clean, and hand washing, you protect both yourself and people in your care.

Always look out for:

• Sudden signs of illness, such as fever, rash, cough, diarrhoea, or wounds that worsen
• Requests for guidance about infection symptoms
• New complaints of itching, discomfort, or unwanted skin changes

Seek advice when someone shows unusual, severe, or lasting symptoms. Early help keeps risks low.

Final Thoughts

Understanding whether an infection comes from bacteria, viruses, fungi, or parasites is key. Each group brings its own challenges in care and prevention. By recognising signs, following best practice and organisational policies, and acting quickly, health and social care workers keep people safe and well.

Keep learning and updating knowledge—guidelines do change as new threats emerge. Good infection control underpins safe care, reduces harm, and supports everyone’s health in care settings.