After starting artemisinin-based treatment for falciparum malaria, parasitaemia should fall quickly. Persistent parasites on a blood smear on day 3 are the accepted clinical marker of possible partial artemisinin resistance, alongside poor adherence, vomiting of doses or a very high starting parasite load.
A day 3 smear is cheap and widely available. Checking it routinely in patients from regions with known resistance turns surveillance into bedside care.
- Record the parasite count at diagnosis so later smears can be compared.
- Repeat a smear on day 3 of treatment, especially after travel to Africa or South-East Asia.
- If still positive, check adherence and absorption before assuming resistance.
- Discuss persistent parasitaemia with an infectious diseases or tropical medicine specialist.
Why it matters
Resistance is found first by clinicians who look, not by surveillance reports.
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