Comparison of Imported Plasmodium ovale curtisi and P. ovale wallikeri Infections among Patients in Spain, 2005-2011

Sequencing data from Plasmodium ovate genotypes co-circulating in multiple countries support the hypothesis that P ovate curtisi and P ovate wallikeri are 2 separate species. We conducted a multicenter, retrospective, comparative study in Spain of 21 patients who had imported P. ovale curtisi infections and 14 who had imported P. ovate wallikeri infections confirmed by PCR and gene sequencing during June 2005-December 2011. The only significant finding was more severe thrombocytopenia among patients with P ovate wallikeri infection than among those with P ovate cultist infection (p = 0.031). However, we also found nonsignificant trends showing that patients with P. ovate wallikeri infection had shorter time from arrival in Spain to onset of symptoms, lower level of albumin, higher median maximum core temperature, and more markers of hemolysis than did those with P. ovate cultist infection. Larger, prospective studies are needed to confirm these findings.