To exclude the possibility that the patient's severe symptoms were due to P. falciparum, which is sympatric with P. vivax in Brazil, a nested PCR using P. falciparum-and P. vivax-specific primers, was performed [16] . The results demonstrated that coinfection with P. falciparum could be excluded (Figure 2A) . Moreover, sputum, blood, and nasopharyngeal swab samples obtained for culture were negative, as were serological tests for atypical respiratory pathogens, human immunodeficiency virus, histoplasma, coccidians, and paracoccidians. Together, these results demonstrated that the clinical symptoms were exclusively due to P. vivax infection.