An overview of Rickettsia diagnostics relevant for Dutch travellers

Abstract

Rickettsioses are zoonotic infections and are emerging infectious diseases among international travellers. Over 450 travel-associated cases have been reported worldwide yet much remains unknown about the scope of these infections. With an increase in recent decades of travel to the tropics, ecotourism and backpacking, it is expected these infections will be continually and increasingly seen in the future. Diagnosis of infections is notoriously difficult, with many methods available however none optimal at confirming diagnosis. Molecular methods are recommended for diagnosis in the early acute phase of rickettsial infections. Using polymerase chain reaction early infection can be identified in patients within days of inoculation. Serology can only be used for diagnosis in the late acute phase of infection, once IgM and IgG levels are detectable. Immunofluorescence assays act as the gold standard for serology, and provide a quick and reliable means of confirming rickettsial infection. Culturing should only be undertaken in severe cases where species diagnosis is of utmost importance. Rickettsioses should always be considered as a differential diagnosis for patients presenting with febrile illness and a suspect travel history.