False-positive rapid diagnostic test for malaria in new world cutaneous leishmaniasis: a tale of two travelers

Ther Adv Infect Dis. 2022 May 9:9:20499361221097791. doi: 10.1177/20499361221097791. eCollection 2022 Jan-Dec.

Abstract

We report two immigrants from Cuba seen in a US travel clinic with a confirmed diagnosis of cutaneous leishmaniasis in whom we also suspected malaria co-infection. Both individuals likely acquired leishmaniasis in the Darien Gap region of Panama during their migratory path to the United States. As part of their clinical workup to rule out malaria, a rapid malaria antigen testing for P. falciparum was obtained and reported positive in both patients, However, both a qualitative reverse transcription-polymerase chain reaction (RT-PCR) for Plasmodium falciparum in blood and repeated thick-and-thin smear direct microscopy were negative in both, deeming the rapid malaria test as a false-positive. Thus, confirmation of malaria in travelers requires thick-and-thin film microscopy. Clinicians should be aware of the growing recognition of the possibility of false-positive malaria rapid diagnostic tests in those with some forms of leishmaniasis.

Keywords: Plasmodium falciparum; cross-reactivity; cutaneous leishmaniasis; leishmaniasis; malaria.

Publication types

  • Case Reports