Core Revision
Best of five: reasoning from the pathogen
21 September 2026 · 4 min read
Two papers of fifty questions, ninety minutes each. The options are close. The way through is to reason from what the organism does — not to remember what a question once looked like.
← All DTM&H Core WisdomRevision aid, not clinical advice. This page is educational material written for exam preparation. It is not a substitute for the current guideline or for clinical judgement, and must not be relied on for the care of any individual. Always check up-to-date national guidance and verify independently before acting on anything here.
Papers 1 and 2 of the DTM&H are best-of-five: 50 questions in 90 minutes each, with no negative marking for wrong or unanswered questions. That is 1 minute 48 seconds a question. The stems are short, and the five options are usually all real diseases, tests or drugs. Recognition alone rarely separates them; reasoning does.
What the stem gives you
- Where they have been. Geography shapes the differential: Plasmodium knowlesi in Malaysian Borneo, melioidosis in north-east Thailand and northern Australia, Loa loa in the rainforests of West and Central Africa.
- How long since exposure. Incubation periods decide what is still possible: dengue within about two weeks of the bite; falciparum malaria usually within weeks, while vivax and ovale can appear months later; visceral leishmaniasis after months, sometimes years.
- One discriminating finding. Eosinophilia, a particular rash, an eschar, a lymph node, splenomegaly, a laboratory clue. Most stems have one. Find it.
Then reason from the biology
Ask how the organism gets in, where it lives, and how it leaves — and what that predicts.
- Helminths that migrate through tissue cause eosinophilia; most gut protozoa do not. Eosinophilia in a returned traveller points towards schistosomiasis, strongyloidiasis or another tissue helminth.
- P. falciparum sequesters in small vessels, which is why it causes cerebral malaria and severe disease. P. vivax and P. ovale leave hypnozoites in the liver, which is why they relapse — and why radical cure with an 8-aminoquinoline, after G6PD testing, matters.
- Salmonella Typhi lives inside cells, so an antibiotic that looks active in the laboratory but does not work intracellularly is the wrong answer, however familiar it sounds.
An option that does not fit the biology is wrong, even if it is the name you half-remember from a similar question.
Before you look at the options, say the stem back to yourself in one line — “fever and eosinophilia, four weeks after swimming in an African lake” — and decide what fits. If your answer is among the five, mark it and move on. If it is not, the stem has a word you have not used yet.
The technique
- Read the lead-in first — most likely diagnosis, best initial test, most appropriate treatment, or preventive advice.
- Cover the options, read the stem, and decide.
- Then look. If your answer is there, take it. If not, eliminate: usually two options contradict the geography or the timing, and one is the right answer to a different question.
- Change an answer only for a reason you can say out loud.
A traveller returns from Malawi, where she swam in the lake. Four weeks later she has fever, an itchy urticarial rash, a dry cough and a raised eosinophil count. Geography (fresh water in Africa), timing (weeks) and the discriminating finding (eosinophilia) point to acute schistosomiasis — Katayama syndrome. Malaria must still be excluded in any febrile traveller from Africa, but it does not explain the eosinophilia, so it is not the best answer to “most likely diagnosis”.
Pace
At 1 minute 48 seconds a question, a checkpoint helps: question 25 at about 45 minutes. Flag anything that has taken two minutes and come back to it. With no negative marking, make sure every question has an answer before time runs out — a flagged best guess beats a blank. The timed papers in the DTM&H Question Bank run to the same clock.
Geography, timing, one finding — then the organism’s biology. Decide before you look, and answer all fifty.
Sitting the DTM&H? Try ten questions free.
The DTM&H package has 850 best-of-five questions with teaching explanations, a 100-specimen image bank and all twelve revision-guide chapters. It is £49.99 for 12 months. Try ten questions first, free and with no sign-up.