engleski

Cases of imported Rickettsia africae infection among travelers to South Africa

Rickettsia spp. are gram-negative, pleomorphic, obligate intracellular parasitic bacteria, causing human diseases of different severities. Rickettsioses are among the oldest known vector-borne diseases as well as among recently increasing emerging and re-emerging infections. With increase in availability of exotic tourist destinations more and more infections and endemic diseases become imported into other regions. One of such diseases is African tick bite fever (ATBF) occuring in sub-Saharan Africa and the eastern Caribbean. After malaria, ATBF is the second most frequent acute systemic febrile illness in travelers returning from southern Africa. The causative agent is Rickettsia africae, transmitted by hard ticks (Amblyomma hebraeum and A. variegatum) with humans being accidental hosts. The disease is usually mild, acute febrile and influenza-like with headache, myalgia, regional lymphadenopathy, maculopapular rash and characteristic (usually multiple) inoculation eschars. Patients are treated with effective antibiotic therapy (including doxycycline, erythromycin, ciprofloxacin, and minocycline) and respond well with full recovery. At the University Hospital for Infectious Diseases "Dr. Fran Mihaljević" in Zagreb, we detect Rickettsia spp. by molecular diagnostic methods. Several samples were taken from three patients returning from a trip to South Africa. DNA was extracted from patients’ wound swabs, lymph node punctate and skin granuloma punctate samples. For all samples a conventional screening polymerase chain reaction (PCR) targeting the Rickettsia spp. partial outer membrane protein B gene (ompB) was performed. The positive results were obtained from the patients’ wound swabs and lymph node punctate samples. Sequencing confirmed that the infections were caused by Rickettsia africae. Identification of the disease causing etiological agent is a prerequisite for an effective therapy and recovery. It is necessary to include rickettsioses in the differential diagnosis of the patients with fever and rash returning from a trip to South Africa.

Rickettsia africae; imported infection; molecular diagnostics; sequencing

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