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Ehrlichiosis, a tick-borne infection, treated with prompt doxycycline.

Rare in the UK, almost always imported. Fever within a fortnight of a tick bite abroad is the clue - and early empirical treatment matters more than waiting for tests.

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Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against UKHSA, NICE CKS, BIA and peer-reviewed tropical medicine sources listed at the end.

  • 03

    Current for 2026

    Reflects current UK practice on tick-borne infection, doxycycline in children and specialist reference testing.

Key facts

Ehrlichiosis at a glance.

The essentials, in plain English - what it is, where it comes from, and how it is diagnosed and treated in the UK today.

  • What it is

    A tick-borne bacterial infection caused by Ehrlichia species, most commonly Ehrlichia chaffeensis (Human Monocytic Ehrlichiosis, HME).

  • Close relative

    Anaplasmosis (Anaplasma phagocytophilum, formerly HGE, now HGA) is clinically similar and shares much of the same workup and treatment.

  • UK context

    Not endemic in the UK. Cases are almost always imported from the USA, parts of Europe or Asia, though tick range is expanding with climate change.

  • Vector

    Amblyomma americanum (Lone Star tick) transmits HME abroad. UK Ixodes ricinus ticks more commonly carry Lyme disease and Anaplasma.

  • Incubation

    Typically 5 to 14 days after a tick bite, with fever, headache, myalgia and often deranged bloods.

  • First-line therapy

    Empirical doxycycline started on clinical suspicion, for all ages including children, without waiting for confirmation.

Why this guide matters

An imported infection that rewards early thinking.

UK clinicians see ehrlichiosis rarely, so the diagnosis rests on remembering to consider it. The three points below shape everything else on this page.

  • Travel and tick history first

    Recent travel to an endemic area and any tick exposure are the two most important clues, more than any single symptom.

  • Bloods do a lot of the work

    Thrombocytopenia, leucopenia and deranged LFTs in a returning traveller with fever should prompt PCR and reference serology.

  • Treat empirically, not later

    Doxycycline is safe and effective for all ages, and delaying it for confirmation is the main driver of severe disease.

How the diagnosis is made

From tick bite to a confirmed diagnosis.

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

  1. 01

    Assessing

    Travel and tick-exposure history

    Recent travel to endemic areas (USA, parts of Europe, Asia), outdoor activity, tick bite or removal, and timing of symptoms.

  2. 02

    Assessing

    Clinical examination

    Fever, headache, myalgia, malaise, nausea and a maculopapular or petechial rash (about 30% adults, 60% children).

  3. 03

    Assessing

    Bedside baseline bloods

    FBC, U&E, LFTs, CRP and coagulation. Thrombocytopenia, leucopenia, elevated transaminases and hyponatraemia are typical.

  4. 04

    Confirming

    Blood film for morulae

    Intraleucocytic inclusions on peripheral film can be pathognomonic, though only detected in 20 to 40% of cases.

  5. 05

    Confirming

    PCR and reference serology

    Specific and sensitive PCR on blood via the UKHSA reference lab, plus paired IgM and IgG samples 2 to 4 weeks apart for a fourfold rise.

  6. 06

    Confirming

    Rule out mimics

    Exclude malaria, Lyme disease, tick-borne encephalitis, other rickettsial infections, dengue and sepsis, guided by travel history.

  7. 07

    Notifying

    Notify and refer

    Notify UKHSA and involve infectious diseases and tropical medicine early, particularly for severe or diagnostically uncertain cases.

Typical timeline: first blood results within hours, PCR and paired serology confirmation over days to weeks.

Symptoms

What ehrlichiosis actually looks like.

A flu-like febrile illness one to two weeks after a tick bite, backed up by classic laboratory changes and, sometimes, a rash.

  • Fever and chills

    Abrupt high fever within days of a tick bite, often the first and most consistent feature.

  • Headache and myalgia

    Severe headache, muscle aches and malaise mirror influenza and other tick-borne infections.

  • Nausea and GI upset

    Nausea, vomiting, abdominal pain and diarrhoea are common, especially in the first week.

  • Rash

    A maculopapular or petechial rash appears in around 30% of adults and 60% of children with HME.

  • Deranged bloods

    Thrombocytopenia, leucopenia, raised transaminases and hyponatraemia are typical laboratory clues.

  • Morulae on blood film

    Intraleucocytic inclusions on peripheral film are highly suggestive when seen, though not always present.

  • Severe disease features

    Meningoencephalitis, ARDS, DIC, multi-organ failure, septic shock and secondary HLH mark severe cases.

  • Red flag - deteriorating patient

    Elderly, immunocompromised or late-presenting patients can deteriorate quickly and need urgent hospital care.

Treatment

How ehrlichiosis is treated in the UK.

Empirical doxycycline first, supportive care throughout, and hospital-level treatment for anyone with organ dysfunction or diagnostic uncertainty.

  • Empirical doxycycline

    Doxycycline 100 mg twice daily for 5 to 14 days is first-line for all ages, including children. Start on suspicion, do not wait for confirmation.

  • Rifampicin (alternative)

    Rifampicin 300 mg twice daily is a specialist-guided alternative in pregnancy or severe doxycycline intolerance.

  • Supportive care

    IV fluids, antipyretics, close monitoring of bloods, and admission for anyone systemically unwell or with organ dysfunction.

  • Broad cover if uncertain

    If the diagnosis is unclear, empirical broad-spectrum antibiotics with rickettsial cover are added until reference testing returns.

  • ICU-level care in severe

    ARDS, DIC, shock or HLH need intensive care, IV doxycycline and management of complications alongside specialist input.

  • Tick avoidance

    DEET, permethrin-treated clothing, long sleeves, light colours, tucked-in trousers, tick checks and a shower after outdoor exposure.

  • Prompt tick removal

    Grasp the tick with fine tweezers close to the skin, pull straight without twisting. Removal within 24 to 48 hours reduces transmission.

  • Specialist referral

    Infectious diseases, tropical medicine and centres such as the Hospital for Tropical Diseases in London, with UKHSA reference support.

What this guide is based on

The sources behind every claim on this page.

UK national guidance, specialist society standards and travel-health authorities, 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.

If you have travelled recently and feel unwell after a tick bite, contact your GP, NHS 111 or an emergency department the same day.

  • UK Health Security Agency (UKHSA). Rare and imported pathogens laboratory - tick-borne infections and reference testing.

  • NICE CKS. Lyme disease and tick-borne infections - primary care overview.

  • British Infection Association (BIA). Guidance on tick-borne and imported infections.

  • CDC. Ehrlichiosis and Anaplasmosis - clinical and epidemiology summaries.

  • NaTHNaC TravelHealthPro. Country-specific tick-borne infection risks and prevention.

Red flags

When ehrlichiosis becomes an emergency.

Around one in seven cases become severe. These are the features that mean hospital admission and, often, intensive care.

  • Meningoencephalitis

    Confusion, neck stiffness, seizures or new neurological signs need urgent admission, imaging and lumbar puncture where safe.

  • ARDS and respiratory failure

    Rising oxygen needs, tachypnoea and bilateral infiltrates warrant critical care review without delay.

  • DIC and bleeding

    Falling platelets, prolonged clotting and bleeding suggest disseminated intravascular coagulation and severe disease.

  • Multi-organ failure

    Rising creatinine, jaundice, shock or lactic acidosis mean intensive care and IV doxycycline are needed now, not later.

  • Secondary HLH

    Persistent fever, cytopenias, splenomegaly and ferritin in the thousands raise concern for haemophagocytic lymphohistiocytosis.

  • Immunocompromise

    Post-transplant, HIV, chemotherapy and asplenia lower the threshold for admission and empirical treatment.

  • Pregnancy

    Any suspected tick-borne infection in pregnancy needs specialist infectious diseases input for both diagnosis and drug choice.

  • Delayed presentation

    Symptoms beyond the first week without treatment carry a higher risk of severe complications and death.

  • Diagnostic uncertainty

    Overlap with malaria, dengue, sepsis and other rickettsial infections is common - do not narrow prematurely.

Prevention

Avoid the bite, and act fast if you get one.

Ehrlichiosis is entirely preventable with sensible outdoor habits. Four things make the biggest difference before, during and after a trip to a tick-heavy area.

A quiet reminder

Removing a tick within 24 to 48 hours matters.

Prompt, careful removal significantly reduces the chance of transmission, so daily tick checks are worth the two minutes they take.

  1. 01 Prevention

    Cover up and use repellent

    Long sleeves, tucked-in trousers, light colours and DEET or permethrin-treated clothing when walking in tick habitats.

  2. 02 Check

    Tick checks after every trip

    A careful head-to-toe check, including scalp, groin and behind the knees, plus a shower within a couple of hours of coming indoors.

  3. 03 Remove

    Remove ticks properly

    Fine tweezers close to the skin, pull straight, no twisting or burning. Clean the site and keep the tick if practical.

  4. 04 Escalate

    Seek care early if unwell

    Fever, headache or rash within a few weeks of travel and tick exposure needs same-day medical review, not watchful waiting.

Frequently asked

Everything we get asked about ehrlichiosis.

Quick answers on symptoms, tests, doxycycline in children and travel prevention.

  • What is ehrlichiosis?

    Ehrlichiosis is a tick-borne bacterial infection caused by Ehrlichia species, most commonly Ehrlichia chaffeensis (Human Monocytic Ehrlichiosis, HME). It is closely related to anaplasmosis (Anaplasma phagocytophilum, formerly HGE, now HGA), which behaves similarly.

  • Is ehrlichiosis found in the UK?

    Ehrlichiosis is not endemic in the UK and almost all cases are imported from the USA, parts of Europe or Asia. UK ticks more commonly transmit Lyme disease and, less often, Anaplasma. Ranges are expanding with climate change so awareness is increasing.

  • How is it diagnosed?

    On a mix of history, examination and tests. Bloods often show thrombocytopenia, leucopenia and raised transaminases. A blood film can show morulae inside white cells. PCR and paired IgM and IgG serology, done through UKHSA reference laboratories, confirm the diagnosis.

  • What is the treatment?

    Empirical doxycycline 100 mg twice daily for 5 to 14 days is first-line for all ages, including children. Treatment should start on clinical suspicion, before test results return. Rifampicin is an alternative in pregnancy or severe doxycycline intolerance, on specialist advice.

  • Is doxycycline safe in children?

    Yes for short courses. Modern evidence shows the benefit of treating suspected ehrlichiosis or Rocky Mountain spotted fever outweighs the small theoretical risk of dental staining from a short course of doxycycline. Delaying treatment is more dangerous than treating.

  • How can I avoid tick-borne infections when travelling?

    Use DEET, wear permethrin-treated clothing, long sleeves and light colours, tuck trousers into socks, do thorough tick checks and shower after outdoor activity. Remove any ticks promptly with fine tweezers, grasping close to the skin and pulling straight. Check NaTHNaC TravelHealthPro before travel.

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