Plasmodium ovale with G6PD deficiency — DTM&H MCQ

Correct answer: D — Seek specialist advice on supervised radical cure or avoid primaquine if unsafe

The correct answer is D, seek specialist advice on supervised radical cure or avoid primaquine if unsafe. P. ovale forms hepatic hypnozoites that require an 8-aminoquinoline (primaquine or tafenoquine) for radical cure, but these drugs oxidise red cells and precipitate severe, sometimes life-threatening haemolysis in G6PD deficiency. Markedly reduced G6PD activity means standard-dose primaquine is unsafe, so UK malaria treatment guidance directs clinicians to involve a specialist (infectious disease or tropical medicine) who can decide between a modified, closely monitored low-dose or weekly regimen under haematological surveillance, or withholding radical cure altogether if deficiency is severe. This individualised, risk-stratified approach protects against haemolysis while still addressing relapse risk where feasible. Why the other options are wrong: A, standard primaquine 14 days: Full-dose primaquine in a patient with markedly reduced G6PD activity risks acute haemolytic anaemia and is contraindicated without specialist input and dose modification. B, tafenoquine as a safer alternative: Tafenoquine is also an 8-aminoquinoline with the same G6PD-dependent haemolytic risk, and its long half-life makes any haemolysis more prolonged and harder to manage, so it is not a safe substitute here. C, chloroquine monthly for life: Chloroquine clears blood-stage parasites but has no activity against liver hypnozoites, so it cannot prevent P. ovale relapse regardless of duration. E, artemether-lumefantrine to eradicate hypnozoites: This is a blood-stage schizonticide with no hypnozoite activity, so it cannot achieve radical cure of P. ovale. Key point: Markedly reduced G6PD activity makes standard 8-aminoquinoline radical cure unsafe, so management must be individualised with specialist guidance rather than defaulting to primaquine, tafenoquine, or non-hypnozoiticidal drugs.

Reference: Journal of Infection / UK malaria treatment guidelines 2016 (Lalloo DG et al., on behalf of PHE Advisory Committee on Malaria Prevention), 'UK malaria treatment guidelines 2016', J Infect 2016;72(6):635-649: https://www.journalofinfection.com/article/S0163-4453(16)00047-5/fulltext