A Case of Imported Plasmodium malariae Malaria

Malaria, the most common vector-borne parasite infection worldwide, results from infection by Plasmodium species. Approximately 80% of malaria cases are caused by P. vivax, which is broadly distributed from tropical to temperate regions; P. falciparum is the second most common infectious species. P. malariae and P. ovale are responsible for a relatively small proportion of malaria cases. Here, we report the case of a 23-yr-old Korean woman who acquired a P. malariae infection while visiting the Republic of Ghana in West Africa for business. She was diagnosed with P. malariae malaria on the basis of peripheral blood smear (PBS) and species-specific conventional and real-time PCR assays for 18S rRNA. She was treated with hydroxychloroquine, and the resulting PBS examination on day 2 suggested that negative conversion occurred. At her 1-month follow-up, however, both the PBS examination and molecular test for malaria demonstrated recurrent parasitemia. We started rescue therapy with mefloquine, and the patient recovered successfully. This is an important finding suggesting possible late recrudescence of a chloroquine-resistant P. malariae strain identified not only by its morphological features, but also by molecular tests.