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Health condition · Clinically reviewed

Brucellosis, undulant fever from an unpasteurised world.

Rare in the UK, common in the Mediterranean and Middle East. A zoonotic infection with a classical waxing fever, focal complications, and a WHO combination antibiotic cure.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against WHO, UKHSA and peer-reviewed infectious disease sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK guidance including WHO combination antibiotic regimens and UKHSA notification pathways.

Key facts

Brucellosis at a glance.

The essentials, in plain English. What Brucella is, how you catch it, and how it is treated in the UK today.

  • What it is

    A zoonotic bacterial infection caused by Brucella species, also known as undulant fever, Malta fever or Mediterranean fever.

  • The bacteria

    B. melitensis (sheep and goats, most virulent), B. abortus (cattle), B. suis (pigs) and B. canis (dogs).

  • Global picture

    Endemic in the Mediterranean, Middle East, Africa, Latin America and Asia. Rare in the UK, almost always imported.

  • How you catch it

    Unpasteurised dairy is the commonest route. Also inhalation, direct animal contact and laboratory exposure.

  • Foundation therapy

    Combination antibiotics for six weeks. Doxycycline plus rifampicin is the WHO first-line regimen.

  • Notifiable disease

    Brucellosis is notifiable to UKHSA. Laboratory exposure triggers post-exposure prophylaxis and Health Protection Team involvement.

Why this guide matters

Rare here, real elsewhere.

Brucellosis is uncommon in the UK, so it is easy to miss. The three points below shape everything else on this page.

  • History wins the diagnosis

    Travel, occupation and unpasteurised dairy intake are the clues that put brucellosis on the differential.

  • Combinations, not monotherapy

    Single-agent regimens have unacceptably high relapse rates. WHO recommends combinations for at least six weeks.

  • Notify UKHSA

    Brucellosis is a notifiable disease in the UK, and laboratory exposures need urgent public health input.

How the diagnosis is made

From returning traveller to a confirmed diagnosis.

The steps a UK infectious diseases team will normally follow, in order, so you know what to expect and why.

  1. 01

    Assessing

    Travel, occupation and food history

    A careful history of travel to endemic regions, occupational exposure (farming, veterinary, abattoir, laboratory) and unpasteurised dairy intake.

  2. 02

    Assessing

    Clinical assessment

    Undulant fever, drenching night sweats, rigors, myalgia, arthralgia and weight loss point to brucellosis in the right context.

  3. 03

    Assessing

    Screen for focal disease

    A structured look for arthritis, spondylitis, orchitis, hepatosplenomegaly, endocarditis and neurological signs.

  4. 04

    Confirming

    Blood cultures with lab alert

    The gold standard. Castañeda biphasic or BACTEC bottles with prolonged incubation up to 21 days. Always inform the laboratory of the suspicion.

  5. 05

    Confirming

    Serology and PCR

    Rose Bengal for screening, Standard Agglutination Test, Coombs, ELISA IgM and IgG, Brucellacapt and PCR for sensitive rapid confirmation.

  6. 06

    Confirming

    Bloods and targeted imaging

    FBC often shows pancytopenia or lymphocytosis, LFTs may be raised. MRI spine for spondylitis, echo for endocarditis, LP for suspected neurobrucellosis.

  7. 07

    Reporting

    Notification and public health

    A statutory notification to UKHSA and the Health Protection Team. Laboratory exposures trigger risk assessment and prophylaxis.

Typical timeline: from suspicion to confirmation in days, with cultures maturing over up to three weeks.

Symptoms

What brucellosis actually feels like.

An incubation of one to four weeks, then the classical undulant fever, drenching sweats and a spectrum of focal complications from bone to heart to brain.

  • Undulant fever

    A classic waxing and waning fever pattern, often with drenching night sweats and rigors.

  • Malaise, myalgia and arthralgia

    Diffuse aching, fatigue and joint pain that can dominate the picture for weeks.

  • Headache and weight loss

    Persistent headache with unintentional weight loss is common in the acute phase.

  • Arthritis and spondylitis

    Large joint arthritis and Pott-like spondylitis. MRI spine helps confirm vertebral involvement.

  • Orchitis and epididymitis

    Painful testicular swelling is a recognised focal complication in men.

  • Hepatosplenomegaly

    Enlarged liver and spleen with abnormal LFTs and occasional hepatic abscess.

  • Neurological features

    Neurobrucellosis can cause meningitis, encephalitis or peripheral neuritis and needs LP and specialist input.

  • Red flag - endocarditis

    Brucella endocarditis is the leading cause of mortality. New murmur or embolic signs need urgent echo.

Treatment

How brucellosis is treated in the UK.

Combination antibiotics for at least six weeks. Focal disease, endocarditis, children and pregnancy each need a modified plan.

  • Doxycycline plus rifampicin

    WHO first-line for uncomplicated adult disease. Doxycycline 100 mg twice daily for six weeks with rifampicin 600 to 900 mg once daily for six weeks.

  • Doxycycline plus streptomycin

    Alternative first-line, often preferred in spondylitis. Doxycycline six weeks with streptomycin 1 g IM for two to three weeks.

  • Triple therapy for focal disease

    Spondylitis and neurobrucellosis need doxycycline plus rifampicin plus streptomycin or ceftriaxone for twelve weeks or more.

  • Endocarditis regimen

    Quadruple antibiotics for at least six months, almost always alongside surgical valve replacement in a specialist centre.

  • Children under eight

    Trimethoprim-sulfamethoxazole with rifampicin. Doxycycline and tetracyclines are avoided in this age group.

  • Pregnancy

    Trimethoprim-sulfamethoxazole with rifampicin. Doxycycline and streptomycin are avoided in pregnancy.

  • Post-exposure prophylaxis

    Laboratory or high-risk exposure is treated with doxycycline and rifampicin for three weeks, with serological monitoring.

  • Follow-up and relapse monitoring

    Clinical review with serology over months. Monotherapy and short courses carry a high relapse rate, so combinations are essential.

What this guide is based on

The sources behind every claim on this page.

WHO guidance, UKHSA notification standards and peer-reviewed infectious diseases literature, 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 infectious diseases team knows your history and exposures and can tell you which parts apply to you. If in doubt, get seen.

  • World Health Organization. Brucellosis in humans and animals.

  • UK Health Security Agency (UKHSA). Brucella: guidance, data and analysis.

  • Public Health England. Brucellosis: notifiable disease reporting.

  • Ariza J et al. Perspectives for the treatment of brucellosis in the 21st century.

  • Corbel MJ. Brucellosis: an overview. Emerging Infectious Diseases.

Red flags

When brucellosis needs urgent attention.

Most cases respond well to combination antibiotics. These are the situations that need urgent specialist input.

  • Endocarditis

    A new murmur, embolic phenomena or heart failure needs urgent echo and cardiology. Brucella endocarditis is the leading cause of death.

  • Neurobrucellosis

    Meningism, focal deficit, cranial nerve palsy or altered consciousness needs LP, MRI and combination therapy with CNS-penetrant agents.

  • Spondylitis

    Focal back pain with fever needs MRI spine. Untreated vertebral disease can cause abscess and spinal cord compromise.

  • Pregnancy

    Brucellosis in pregnancy carries a real risk of miscarriage. Urgent obstetric and infectious diseases input is needed.

  • Laboratory exposure

    Brucella is a Category 3 pathogen and highly infectious. Any laboratory exposure needs risk assessment, prophylaxis and UKHSA involvement.

  • Relapse after treatment

    Recurrent fever, sweats or focal symptoms after a course of antibiotics should prompt repeat cultures, serology and a longer regimen.

  • Cytopenias

    Significant pancytopenia or bleeding needs urgent haematology review alongside infection treatment.

  • Chronic disease

    Symptoms beyond twelve months, with arthritis, spondylitis, depression or fatigue, need specialist infectious diseases input.

  • Hepatic abscess or splenic disease

    Focal collections seen on imaging need drainage discussion alongside prolonged combination antibiotics.

Living with it

A treatable infection, with a clear plan.

Four things make the biggest difference to a full recovery: full compliance, structured follow-up, food safety and workplace precautions.

A quiet reminder

Six weeks of two antibiotics beats six months of one.

Relapse is nearly always about stopped drugs or single-agent regimens. Stick with the plan.

  1. 01 Compliance

    Finish every dose

    Combination antibiotics for six weeks are the minimum. Stopping early is the commonest cause of relapse.

  2. 02 Follow-up

    Keep the review appointments

    Serology and clinical review continue for months. Relapse is best caught early through structured follow-up.

  3. 03 Prevention

    Avoid unpasteurised dairy

    Soft goat and sheep cheeses from endemic regions are the main food risk. Pasteurised only, especially when travelling.

  4. 04 Occupation

    Use PPE at work

    Farmers, vets, abattoir and laboratory workers need occupational health input, PPE and BSL-3 handling where relevant.

Frequently asked

Everything we get asked about brucellosis.

Quick answers on transmission, testing, WHO regimens and UK notification.

  • What is brucellosis?

    Brucellosis is a zoonotic bacterial infection caused by Brucella species. It is also known as undulant fever, Malta fever or Mediterranean fever, because of its classic waxing and waning fever pattern and its links to the Mediterranean basin.

  • How do people catch brucellosis?

    The commonest route is ingesting unpasteurised dairy, especially goat and sheep cheeses. Other routes are inhalation in abattoirs and laboratories, direct contact with infected animals or parturition products, and laboratory exposure. Brucella is highly infectious in the laboratory setting.

  • Is brucellosis common in the UK?

    No. Brucellosis is rare in the UK and is almost always seen in returning travellers, migrants from endemic regions, or people with occupational exposure. It remains endemic across the Mediterranean, Middle East, Africa, Latin America and much of Asia.

  • How is brucellosis diagnosed?

    Diagnosis starts with a careful travel, food and occupational history. Blood cultures are the gold standard but need prolonged incubation, so always tell the laboratory the suspicion. Serology (Rose Bengal, SAT, Coombs, ELISA, Brucellacapt) and PCR add speed and confirmation. MRI, echo and LP are used when focal disease is suspected.

  • What is the treatment?

    Combination antibiotics for six weeks. The WHO first-line regimen is doxycycline 100 mg twice daily plus rifampicin 600 to 900 mg once daily for six weeks. Doxycycline with streptomycin is an alternative, often preferred for spondylitis. Focal disease, endocarditis, children and pregnancy need modified regimens.

  • Do I need to tell anyone if I have brucellosis?

    Yes. Brucellosis is a notifiable disease in the UK. Your clinician will notify UKHSA and the local Health Protection Team. If the case involves laboratory exposure, colleagues are risk-assessed and offered post-exposure prophylaxis.

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