Parasitic procrastination: late-presenting ovale malaria and schistosomiasis

A 29-year-old woman with ovale malaria (most likely contracted, together with asymptomatic schistosomiasis, in East Africa two years previously) had fever, nausea and confusion, jaundice, anaemia, thrombocytopenia, hyponatraemia and hypokalaemia. She was initially diagnosed with and treated for blood-smear-positive vivax malaria. Because of the unusual clinical presentation, blood was analysed by a malaria species-specific nested polymerase chain reaction (PCR) assay which identified Plasmodium ovale as the only infecting species. This case illustrates (i) that a detailed travel history remains a vital part of clinical assessment, (ii) ovale malaria can have an exceptionally long incubation period and features of a moderately severe acute infection, and (iii) PCR assay may prove a valuable adjunct to blood film examination in the diagnosis and speciation of malaria.