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Health condition · Clinically reviewed

Infectious diseases, from common infections to specialist commissioned care.

Bacteria, viruses, fungi, parasites and prions - what they look like, how UK services diagnose them and how they are treated safely under stewardship.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a UK-registered infection specialist before publication.

  • 02

    Sourced from guidance

    Checked against NICE, UKHSA, BIA and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK guidance including antimicrobial stewardship, UKHSA notifiable disease pathways and specialist commissioned services.

Key facts

Infectious diseases at a glance.

The five families of infection you will meet in UK practice - what defines each and where each is treated.

  • What it covers

    A hub guide to bacterial, viral, fungal, parasitic and prion infections - how they present, how they are diagnosed and how they are treated in the UK.

  • Bacterial infection

    Respiratory, urinary, skin, sepsis, endocarditis and meningitis lead the workload - treated with targeted antibiotics under stewardship.

  • Viral infection

    Respiratory (COVID-19, influenza, RSV), enteric, sexually transmitted, hepatitis and childhood viruses - many now preventable by vaccination.

  • Fungal infection

    From common candidiasis to invasive aspergillosis and mucormycosis - increasingly relevant in immunosuppression.

  • Parasitic infection

    Protozoa (malaria, Chagas), helminths and ectoparasites - travel history and exposure are central to diagnosis.

  • Notifiable diseases

    Certain infections must be reported to UKHSA under the Health Protection Regulations - a legal duty for UK clinicians.

Why this guide matters

One hub, five families, a clear pathway.

Infection care in the UK is a team sport - GPs, infection specialists, microbiologists, sexual-health services, tropical medicine and UKHSA - all knitted together by stewardship and public health.

  • History does most of the work

    Travel, exposure, immunosuppression and vaccination history narrow the differential faster than any single test.

  • Prevention beats treatment

    Vaccination, hand hygiene, safer sex and food safety prevent more infections than antibiotics ever cure.

  • Some infections are notifiable

    UKHSA notification is a legal duty for suspected cases - it protects contacts and detects outbreaks early.

How the diagnosis is made

From first fever to an organism-specific plan.

The steps a UK GP, hospital physician or infection specialist will normally follow - so you know what to expect and why.

  1. 01

    Assessing

    Structured infection history

    Onset, fever pattern, systemic symptoms, exposures, contacts, occupation and unwell household members.

  2. 02

    Assessing

    Travel and exposure history

    Countries, dates, activities, insect bites, freshwater exposure, sexual contacts and animal contacts - each opens a different differential.

  3. 03

    Assessing

    Immunosuppression review

    HIV, chemotherapy, transplant, biologics, steroids, splenectomy and diabetes all change the organism list and urgency.

  4. 04

    Assessing

    Vaccination and prophylaxis

    Childhood schedule, boosters, travel vaccines, HPV and hepatitis B status - and any malaria or PEP taken.

  5. 05

    Confirming

    Targeted microbiology

    Blood cultures, urine, stool, sputum, wound swabs, PCR panels, serology and NAAT - guided by the syndrome, not sent by reflex.

  6. 06

    Confirming

    Imaging when needed

    Chest X-ray, CT or MRI to localise infection - abscess, endocarditis, osteomyelitis or CNS involvement.

  7. 07

    Referring

    Specialist infection referral

    Complex, imported, immunocompromised or notifiable cases go to UK infectious diseases services and MDT.

Typical timeline: a first assessment to an organism-specific plan in hours to days.

Symptoms

What infection can look like.

The core syndromes you will meet - and the features that mean this is not a mild self-limiting illness.

  • Fever and rigors

    The commonest sign - pattern, height and associated features narrow the differential considerably.

  • Respiratory symptoms

    Cough, sputum, breathlessness and pleuritic pain - see our guides on chest infection and tuberculosis.

  • Urinary symptoms

    Dysuria, frequency, loin pain and confusion in older adults - see our guide on kidney infection.

  • Skin and soft-tissue signs

    Spreading erythema, blistering, ulceration or pustules - see our guides on cellulitis and impetigo.

  • Gastrointestinal upset

    Diarrhoea, vomiting and abdominal pain - viral, bacterial or parasitic causes, some notifiable to UKHSA.

  • Neurological features

    Headache, neck stiffness, altered consciousness or focal signs - possible meningitis or encephalitis, an emergency.

  • Rash with fever

    From measles and chickenpox to meningococcal purpura - the pattern and time-course tell the story.

  • Red flag - sepsis physiology

    Hypotension, tachycardia, tachypnoea, mottling or confusion - call 999 or attend A&E immediately.

Treatment

How infection is treated in the UK.

Targeted antimicrobials, vaccination and supportive care - delivered under stewardship and, for the most complex cases, in specialist commissioned centres.

  • Targeted antibiotics

    Empirical then narrowed by culture - guided by local UK antimicrobial policies and stewardship rules.

  • Antivirals

    Oseltamivir for influenza, aciclovir for herpes viruses, HIV combination therapy and hepatitis-specific regimens.

  • Antifungals

    Azoles, echinocandins and amphotericin - for candidiasis, aspergillosis, cryptococcosis and mucormycosis under specialist care.

  • Antiparasitics

    Artemisinin-based regimens for malaria, ivermectin for strongyloides and permethrin for scabies - travel history drives choice.

  • Vaccination

    Prevention first - see our travel, HPV, hepatitis B, flu, MMR, childhood and monkeypox vaccination clinics.

  • Supportive care

    Fluids, oxygen, antipyretics and organ support - the backbone of severe infection care alongside antimicrobials.

  • Specialist commissioned care

    NHS England commissions high-consequence infection care at Royal Free, Liverpool and the Hospital for Tropical Diseases.

  • Antimicrobial stewardship

    Right drug, right dose, right duration - reviewed at 48 to 72 hours to protect future generations from resistance.

What this guide is based on

The sources behind every claim on this page.

UK national guidance, specialist society standards and public-health regulations, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or infection specialist can tell you which parts apply to your specific illness. If you are seriously unwell, phone 999 or 111 or attend A&E.

  • NICE. Antimicrobial prescribing guidelines (NG series).

  • UKHSA. Notifiable diseases and causative organisms: how to report.

  • British Infection Association (BIA). Position statements on infection management.

  • BASHH. UK national guidelines on sexually transmitted infections.

  • JCVI and UKHSA Green Book. Immunisation against infectious disease.

  • NHS England. Specialised services for high-consequence infectious diseases.

Red flags

When infection needs urgent attention.

Most infections settle with time, rest or a short course of the right antimicrobial. These situations do not - and need urgent hospital care.

  • Sepsis

    Fever, tachycardia, hypotension or confusion - a medical emergency needing IV antibiotics within one hour.

  • Meningococcal septicaemia

    Non-blanching rash with fever - call 999. Time to antibiotics changes outcomes.

  • Encephalitis or meningitis

    Headache with fever, neck stiffness or altered consciousness - urgent hospital assessment and lumbar puncture.

  • Returned traveller with fever

    Fever within 21 days of travel to a malarial area is malaria until proven otherwise. Same-day assessment.

  • Neutropenic fever

    Fever during chemotherapy or in immunosuppression - straight to hospital under the local neutropenic sepsis pathway.

  • Endocarditis features

    New murmur with prolonged fever, embolic phenomena or splinter haemorrhages - urgent echocardiography and blood cultures.

  • Notifiable disease suspected

    Measles, TB, meningitis, food poisoning, viral haemorrhagic fever - report to UKHSA on clinical suspicion, not after confirmation.

  • Necrotising soft-tissue infection

    Pain out of proportion, rapid spread, skin dusky or blistered - surgical emergency requiring immediate debridement.

  • High-consequence infection

    Suspected viral haemorrhagic fever, monkeypox or novel respiratory pathogen - isolate and contact the on-call service immediately.

Living with it

Prevention, hygiene, and knowing when to escalate.

Four practical habits that reduce your infection risk day to day - and one clear rule for when something feels wrong.

A quiet reminder

If you think it might be sepsis, act like it is sepsis.

You will never be criticised for phoning 999 or attending A&E with concerning features. Minutes matter.

  1. 01 Prevention

    Vaccination is the biggest lever

    Keep childhood, travel and adult boosters up to date - the single most cost-effective intervention in medicine.

  2. 02 Hygiene

    Simple habits, big effect

    Hand hygiene, safe food and water, insect avoidance and safer sex prevent most preventable infections.

  3. 03 Stewardship

    Take antibiotics as prescribed

    Complete the course your clinician actually recommends, no more and no less - and never share leftover antibiotics.

  4. 04 Escalate

    Know the sepsis signs

    Slurred speech, extreme shivering, passing no urine, severe breathlessness, mottled skin - call 999 or attend A&E.

Frequently asked

Everything we get asked about infectious diseases.

Quick answers on fever, notifiable diseases, stewardship, specialist care and vaccination.

  • What is an infectious disease?

    A disease caused by a pathogen - bacteria, virus, fungus, parasite or prion - that can be transmitted between people, from animals, from the environment or via vectors. UK infection care spans primary care, hospital services, sexual health, tropical medicine and specialist commissioned centres.

  • When should I see a doctor about a fever?

    Same-day if fever is accompanied by breathlessness, chest pain, severe headache with neck stiffness, a non-blanching rash, confusion, reduced urine output or persistent vomiting. Any fever in a returned traveller, a pregnant person, an infant under three months or an immunosuppressed patient should be assessed the same day.

  • Which infectious diseases are notifiable in the UK?

    Under the Health Protection Regulations, UK clinicians must notify UKHSA of suspected cases of a defined list including measles, meningococcal disease, tuberculosis, food poisoning, viral haemorrhagic fever and many others. Notification is based on clinical suspicion, not laboratory confirmation.

  • Why does antimicrobial stewardship matter?

    Antimicrobial resistance is one of the top global health threats. Using antibiotics only when needed, choosing the narrowest effective agent and stopping at the right time preserves future effectiveness. UK stewardship programmes review therapy at 48 to 72 hours to switch, narrow or stop.

  • Where does the UK treat the most complex infections?

    NHS England commissions high-consequence infectious disease care at the Royal Free London, the Royal Liverpool University Hospital and the Hospital for Tropical Diseases in London. London specialist sexual health and tropical medicine services also form part of the network.

  • Which vaccines are most important for adults?

    Keep tetanus, MMR, hepatitis B and HPV status current. Add annual flu and COVID-19 boosters if eligible, pneumococcal and shingles vaccines at the recommended ages, and travel vaccines before high-risk trips. Ask your GP or a travel clinic for a personal plan.

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