DHFR and malaria: Among peptide sequences of DHFR-TS in isolates of P. ovale curtisi and P. ovale wallikeri studied herein, mutations known to confer antifolate resistance in other species of malaria, notably P. falciparum were not demonstrated Furthermore, non-synonymous mutations within each sub-species, P. ovale wallikeri in particular, were also observed, confirming previous reports [2].