General Medicine
Fever: Investigation and Management
Fever investigation and management for MBBS: staged testing, cultures and the Mantoux test, species-based antimalarial therapy and empirical treatment, mapped to NMC codes IM4.16 to IM4.26.
MedNext Academy | 3 min read
Fever: Investigation and Management
Fever investigation and management for MBBS: staged testing, cultures and the Mantoux test, species-based antimalarial therapy and empirical treatment, mapped to NMC codes IM4.16 to IM4.26.
This chapter continues the febrile-patient workup, focusing on staged investigation, marrow and culture sampling, and the interpretation of the Mantoux test. It sets out species-based antimalarial prescribing, empirical therapy while awaiting results, and counselling for malaria prevention.
High-yield: Fever: Investigation and Management
- A prioritised, staged investigation plan avoids over-testing and targets the most likely causes first.
- Inflammatory markers such as the erythrocyte sedimentation rate and C-reactive protein are sensitive but non-specific pointers.
- Bone marrow aspiration and biopsy can diagnose infiltrative, haematological and some infective causes of prolonged fever.
- Blood cultures should be drawn before starting antibiotics whenever the patient is stable enough to allow it.
- The Mantoux test measures induration, not erythema, read at 48 to 72 hours to assess tuberculosis exposure.
- Chloroquine still treats sensitive vivax malaria, but chloroquine-resistant falciparum needs an artemisinin-based combination.
- Severe or complicated falciparum malaria is treated with intravenous artesunate.
- Radical cure of vivax and ovale malaria requires primaquine to clear the liver hypnozoites after checking G6PD status.
- Empirical therapy pending diagnosis should be guided by the most dangerous treatable possibilities.
- Cross-sectional imaging is reserved for localising signs or when first-line tests are unrevealing in prolonged fever.
- Serological and molecular tests confirm specific pathogens once the differential has been narrowed.
- Malaria chemoprophylaxis and personal protection reduce risk for travellers to endemic areas.
- Clear communication of the diagnosis and treatment plan improves adherence and follow-up.
- Antimalarial resistance patterns should be checked against current national programme guidance before prescribing.
- Wound and blood culture technique must be sterile to avoid contamination and misleading results.
Investigating and treating prolonged fever
- **Staged testing:** Prioritise likely causes first; reserve imaging and marrow for unrevealing or localising cases.
- **Cultures:** Draw blood cultures before antibiotics whenever the patient is stable enough.
- **Malaria therapy:** Artemisinin combination for resistant falciparum, intravenous artesunate for severe disease, primaquine for radical cure.
- **Mantoux:** Read induration at 48 to 72 hours to assess tuberculosis exposure.
NMC competencies in this chapter
- **IM4.16:** Inflammatory, serologic and bone marrow tests in prolonged fever
- **IM4.18:** Imaging in febrile syndromes
- **IM4.19:** Blood and wound culture collection
- **IM4.20:** Interpretation of the Mantoux tuberculin test
- **IM4.21:** A prioritised diagnostic plan for fever
- **IM4.22:** Antimalarial pharmacology and resistance
- **IM4.23:** Species-based malaria prescription
- **IM4.24:** Empirical treatment pending diagnosis
Frequently Asked Questions
How is the Mantoux test interpreted?
It is read at 48 to 72 hours by measuring the diameter of induration, not the redness, with the cut-off for a positive result varying by the patient's risk category.
Why is primaquine needed in vivax malaria?
Primaquine clears the dormant liver hypnozoites of vivax and ovale malaria to achieve radical cure and prevent relapse, but G6PD status must be checked first to avoid haemolysis.
When should blood cultures be taken?
Blood cultures should ideally be drawn before the first antibiotic dose whenever the patient is stable enough, because prior antibiotics reduce the yield.
How does this chapter help for NEET-PG?
Mantoux interpretation, artemisinin-based combinations, artesunate for severe malaria and primaquine radical cure are common exam points, so this material maps straight to questions.
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