Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
Latent infection screening before immunosuppression
Essential points for quick revision.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Active infection or imminent immunosuppression
Symptoms of active tuberculosis, hepatitis, systemic infection or Strongyloides hyperinfection require diagnostic and treatment pathways rather than a latent-infection label; urgent organ-saving immunosuppression may leave no time for routine screening completion.
Action: Stabilise and sample suspected active disease, defer non-urgent immunosuppression, and contact infection, TB, hepatology or tropical-medicine specialists. When immune treatment cannot wait, begin parallel pathogen-directed treatment or prophylaxis and monitoring through an explicit multidisciplinary risk plan.
Synopsis
Detect active and latent infections before immune control is weakened, interpret imperfect tests in context, complete prevention safely and avoid delaying urgent treatment without an agreed containment plan.
Screen before the first immunosuppressive dose whenever possible, because corticosteroids and targeted agents reduce test sensitivity, accelerate reactivation and narrow vaccination options.
Begin with birthplace, residence and travel, TB contact and treatment, blood and sexual exposure, previous hepatitis, recurrent infection, VZV history, vaccines, prior biologics and planned drug mechanism.
TB assessment combines symptom review, examination, chest radiography and IGRA, with TST added when appropriate; no single test is a gold standard for latent infection.
Key red flags
Cough, fever, weight loss, night sweats, haemoptysis, lymphadenopathy or abnormal chest imaging requires active-tuberculosis investigation and appropriate respiratory isolation before latent treatment.
Possible active tuberculosis
Constitutional, respiratory, nodal, spinal, abdominal or neurological symptoms and abnormal imaging require site-specific microbiology before the result is classified as latent infection.
Investigation priorities
01
Structured exposure and treatment historyFirst step
Set pre-test probability, identify active symptoms and determine which latent or vaccine-preventable infections matter for the planned mechanism.
02
First-line TB screenFirst line
Identify immune sensitisation and radiographic evidence of previous or current tuberculosis before biologic or substantial immunosuppressive treatment.
Management branches
BASELINEBuild the screening set
A biologic, targeted drug, conventional immunosuppressant, prolonged corticosteroid course, chemotherapy or transplantation is being planned.
Define the treatment mechanism, expected intensity and start date, then take a structured infection, travel, vaccination and previous-treatment history.
Check FBC, renal and liver profiles and complete core infection testing early enough to act on results without unnecessary therapeutic delay.
Key medicines
Rifampicin plus isoniazid for latent TBGive daily for 3 months with pyridoxine under the TB service; a person at least 50 kg commonly receives rifampicin 600 mg plus isoniazid 300 mg once daily.
Isoniazid for latent TBGive isoniazid 300 mg orally once daily with pyridoxine for 6 months in a typical adult, supervised and modified by the TB service for weight, age, liver risk and pregnancy.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.