False-Positive Malaria Rapid Diagnostic Test Likely Due to African Tick Bite Fever: A Case Report.

Background and Clinical Significance: Fever in the returning traveler is a medical emergency warranting prompt exclusion of potentially life-threatening infections such as malaria. Case Presentation: We describe a case of a febrile returned traveler to South Africa whose prompt initial diagnostic work-up was notable for a false-positive malaria rapid diagnostic test (RDT), and who nevertheless responded quickly to oral atovaquone-proguanil, despite an ultimate diagnosis of African tick bite fever. Subsequent RDT and malaria thick- and thin-film blood examination failed to corroborate a diagnosis of malaria and all other microbiological testing other than rickettsial serology remained non-contributory. Conclusions: The case presented highlights important points regarding diagnostic test performance characteristics and premature diagnostic closure.