Infectious Disease Calculators

29 calculators & risk scores

Browse 29 Infectious Disease clinical calculators and risk scores used in everyday UK practice. Every tool runs entirely in your browser — enter the values and get instant scoring, colour-coded interpretation bands and a link to the underlying guideline or publication. ClinCalc Pro is free, needs no sign-up, and is built for working clinicians.

These infectious disease tools span Diagnosis, Prognosis, Treatment, Throat, Bone & Joint Infection, Tuberculosis and more.

Quick SOFA (qSOFA) — Sepsis-3

Quick SOFA (qSOFA) for rapid sepsis identification outside ICU. Score ≥2 warrants full assessment.
PORT Score / PSI for Pneumonia

Pneumonia Severity Index (PSI) for stratifying CAP mortality risk. Patients in classes I–II can be treated as outpatients.
HIV Risk Assessment (MSM/Heterosexual)

Estimates estimated HIV transmission risk per exposure type to counsel patients and guide PrEP/PEP decisions.
Clinical Pulmonary Infection Score (CPIS)

Diagnoses ventilator-associated pneumonia (VAP) and hospital-acquired pneumonia (HAP). Score >6 suggests VAP.
Fever in Neutropenia Risk (MASCC)

Multinational Association for Supportive Care in Cancer (MASCC) index for febrile neutropenia. Score ≥21 = low risk.
IE Prophylaxis Indication

Identifies patients requiring antibiotic prophylaxis before dental procedures based on ESC/AHA guidelines.
WHO Severe Malaria Criteria

WHO 2015 criteria for severe P. falciparum malaria requiring parenteral artesunate and ITU-level care.
FeverPAIN Score for Strep Throat

UK-derived 5-item clinical score to predict Group A Strep pharyngitis and guide antibiotic prescribing. Validated in UK primary care. Endorsed by NICE NG84.
Kocher Criteria for Septic Arthritis

Predicts probability of septic arthritis vs transient synovitis in children with acute hip pain. Validated by Caird et al. with CRP enhancement.
Mantoux Test / TST Interpretation (TB)

Tuberculin skin test (Mantoux) interpretation for latent TB infection using the NICE NG33 threshold — an induration of 5 mm or larger, regardless of BCG history.
HIV Incidence Risk Index for MSM (HIRI-MSM)

Screening index identifying HIV-negative men who have sex with men at highest risk of HIV acquisition, derived in two US cohorts (VAX004 and EXPLORE). Score 0–47; a score of 10 or more (sensitivity 84%, specificity 45%) identifies men to evaluate for PrEP and intensive prevention.
HIV Post-Exposure Prophylaxis after Sharps or Splash Exposure (BASHH 2021)

Applies the 2021 UK (BASHH/BHIVA) recommendations on HIV post-exposure prophylaxis (PEP) after an occupational sharps or mucosal splash exposure, by source HIV status, type of exposure and time since exposure.
HIV CD4/Viral Load Monitoring Intervals

CD4 count and viral load monitoring in people living with HIV (PLHIV) on antiretroviral therapy (ART). Intervals are set by the BHIVA routine investigation and monitoring guideline and the treating HIV clinic.
SOFA Score (Sepsis-3)

Sequential Organ Failure Assessment (SOFA) score for organ dysfunction in ICU. Core of Sepsis-3 definition: sepsis = SOFA increase >=2.
HIV CD4 Opportunistic Infection Risk

Stratifies risk of AIDS-defining opportunistic infections based on CD4 count. Guides prophylaxis decisions and clinical monitoring.
Dengue Severity Classification (WHO 2009)

Classifies dengue fever severity using WHO 2009 criteria. Guides fluid management, monitoring, and hospital admission decisions.
Lower Respiratory Tract Infection (LRTI) Severity Score

CURB-65 severity score for adults with community-acquired pneumonia (Lim 2003). In the community, without a urea result, NICE CG191 uses CRB-65.
Influenza Severity Score (FluSS)

Identifies high-risk influenza patients requiring antiviral therapy (oseltamivir) and hospital-level care.
Hepatitis B Treatment Indication Score

Guides antiviral therapy decision in chronic hepatitis B based on HBeAg status, viral load, ALT, and fibrosis stage.
TB Directly Observed Therapy Criteria (NICE NG33)

NICE NG33 criteria for offering directly observed therapy (DOT) as part of enhanced case management for active TB. In children whose parents meet any criterion, offer DOT too (NICE NG33 1.7.1.4).
Malaria Severity Assessment (WHO Criteria)

Classifies malaria as uncomplicated vs severe per WHO 2015 criteria. Severe malaria (Plasmodium falciparum) requires IV artesunate, not oral therapy.
Duke Criteria for Infective Endocarditis

Diagnoses infective endocarditis using major and minor Duke criteria. Guides echocardiography, blood culture interpretation, and empirical antibiotic selection.
HIV Opportunistic Infection Risk (CD4-Based)

Predicts risk of specific opportunistic infections by CD4 count threshold. Guides prophylaxis and diagnostic priorities in HIV-positive patients.
Fever in Returning Traveller Assessment

Stratifies risk and guides urgent investigation in febrile returning travellers. Malaria must be excluded in all cases.
Clostridioides difficile Severity Grading

Grades C. difficile infection (CDI) severity using ESCMID/IDSA criteria. Guides fidaxomicin vs vancomycin vs bezlotoxumab vs surgery decisions.
MASCC Score (Febrile Neutropenia Risk)

Predicts risk of serious complications in febrile neutropenia. MASCC score >=21 identifies low-risk patients eligible for outpatient oral antibiotic management.
Toxoplasmosis Risk Assessment (Congenital and Immunocompromised)

Assesses risk of active or congenital toxoplasmosis. Guides spiramycin/pyrimethamine-sulphadiazine therapy and neonatal screening.
Pitt Bacteraemia Score

Severity score in patients with bloodstream infection (Hilf 1989). Predicts mortality and used to stratify patients in clinical trials of new antibiotics. Sums 5 weighted variables (max 14); ≥ 4 = critically ill.
Jarisch-Herxheimer Reaction Severity Assessment

Acute febrile reaction occurring within 24 h of antibiotic treatment for spirochaete infections (syphilis, leptospirosis, Lyme, relapsing fever). Categorise severity for management.