Performance of Two Rapid Tests forPlasmodium falciparumMalaria in Patients with Rheumatoid Factors

Abstract

Light-microscopical examination of blood smears is the cornerstone of the diagnosis of malaria. Recently, two rapid immunodiagnostic tests, the ParaSight F test (Becton Dickinson, Cockeysville, Md.)¹ and the ICT Malaria Pf test (ICT Diagnostics, Balgowlah, Australia) ,² were developed for the diagnosis of Plasmodium falciparum infection. Both are immunochromatographic tests based on the detection of circulating P. falciparum histidine-rich protein-2 antigen in whole blood.³ Recently, Laferl [not Laferi, as published] et al., in a letter to the editor,⁴ and Bartoloni et al.⁵ reported false positive results of ParaSight F tests in 67 percent and 68 percent of patients with rheumatoid factors, respectively. Since the production of rheumatoid factors occurs commonly in patients with a variety of infectious and noninfectious diseases, as well as in 5 percent of the healthy people, caution was urged in the use of the ParaSight F test.