DHFR and malaria: As resistance to the proguanil component of AP is conferred in P. falciparum by step-wise mutations of the Dhfr gene, understanding whether or not similar mutations can accumulate in P. ovale, and whether such mutations are over-represented among a particular sub-species of P. ovale, is important for informing empiric choice of anti-malarials in a patient with unspeciated malaria.