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

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

Transfusion transmissible malaria: seroprevalence of malaria parasitemia in blood donors in Garhwal region of Uttarakhand, India

“…False positive RDTs are generally seen in conditions such as Rheumatoid arthritis (RA factor positive patients) ( 30 ), circulating HRP-2 antigen after successful treatment ( 31 ), African trypanosomiasis ( 32 ), schistosomiasis and Salmonella Typhi infection. False positive P. falciparum RDT test can be seen in patients suffering from Leishmaniasis ( 33 ). The RDT test kit used in the present study had a sensitivity of 95.5% (P.v) to 99.7% (P.f), and a specificity of 99.5%.…”