Antibody to Arenaviruses in Rodents, Caribbean Colombia

(5′-GTGGAGCAAATGCAGGACA ACCGAATGCAG-3 ′;5 ′-AGCAA AT G C A G G A C A A C C G A AT GCAGAAGG-3′) in the csp gene of Pkpah-1. Furthermore, the alignment showed 21 variable sites between the genes. Phylogenetic analysis based on SSU rRNA sequences indicated that Pkpah-1 and Pkprk-1 formed a cluster, which was more related to P. knowlesi isolates from Thailand than to isolates from Sarawak, a Malaysian state in Borneo Island (Figure). Another isolate from Peninsular Malaysia, KAL-1, was also grouped with Pkpah-1 and Pkprk-1. The KAL-1 isolate was detected in a traveler from Finland returning from Peninsular Malaysia in 2007 (7). P. knowlesi infection does not relapse because the parasite has no liver hypnozoite stage (8). Reinfection and recrudescence are not uncommon in malaria. The fi nding in the patient reported here indicates reinfection rather than recrudescence as confi rmed by PCR genotyping. He acquired his infection while jungle trekking in Raub in October 2009 and was reinfected in Tanjung Malim in June 2010 (the great-circle distance between the 2 locations is 38.61 km). This case shows that immunity toward P. knowlesi infection is strain specifi c as has been observed in other malaria species (9). P. knowlesi is a nonhuman primate malaria species, and humans are accidental hosts when they go into areas where macaques dwell. P. knowlesi can cause reinfection and can potentially be severe in areas where it is endemic. Travelers to forested areas of endemicity should be advised to take strict antimosquito measures and prophylaxis. Physicians should be aware that P. knowlesi infection is a vital differential diagnosis in febrile travelers with a recent travel history to forested areas in Southeast Asia.