Rickettsiosis cases presenting with rash: a case series from an endemic region in Turkey

Abstract

Rickettsia species are Gram-negative, pleomorphic coccobacilli that are obligate intracellular pathogens transmitted by arthropod vectors such as ticks. Among them, Rickettsia conorii, the causative agent of Mediterranean spotted fever (MSF), is endemic in many Mediterranean countries, including Turkey. This case series describes three patients from Balıkesir, Turkey, who developed high-grade fever, generalized maculopapular rash involving the palms and feet soles, arthralgia, and necrotic eschars (tache noire) at the tick bite sites. All cases occurred during summer and had documented exposure to Rhipicephalus sanguineus. Laboratory evaluations ruled out other tick-borne diseases, while real-time PCR performed on skin biopsy samples confirmed Rickettsia spp. Subsequent DNA sequencing of the gltA and ompA gene regions enabled species identification. Additionally, serological tests showed a significant rise in IgM and IgG antibody titers reacting with Rickettsia conorii antigen by indirect immunofluorescence assay. All patients were treated with doxycycline and recovered without complications. This case series highlights the importance of considering rickettsial infections in the differential diagnosis of febrile patients with rash and recent tick exposure, especially in endemic regions during warm seasons.