Spotted fever group rickettsiae associated with ixodid ticks in wild environment in Southern Italy

Ixodidae ticks are vectors and reservoirs of several species of rickettsiae, and tick-borne rickettsioses are reported worldwide. This study was aimed to verify the distribution of spotted fever group rickettsiae associated with ticks in a wild environment, the National Park of Gargano, where there is proximity between wild and domestic animals, and which is within an endemic area for rickettsiosis. Ticks were collected from animals or vegetation, morphologically identified and tested by a PCR targeting the 17kDa gene, and by a loop-mediated isothermal amplification (LAMP) targeting ompB gene. Out of 34 tested tick pools, 2 from Dermacentor marginatus, 1 from Ixodes ricinus, and 1 from Rhipicephalus turanicus resulted positive. Nucleotide sequences of amplicons showed high similarity with sequences from Rickettsia slovaca, Rickettsia raoultii, Rickettsia helvetica, and Rickettsia felis. The overall calculated infection rate was 26.19 per 1,000, while it rose up to 107.77 when only D. marginatus was considered. The results highlight the association among Ri. slovaca, Ri. raoultii, D. marginatus and wild boars from which infected ticks were collected. Finally, the study shows the low efficacy of the previously described LAMP method for the detection of Rickettsia spp., when compared to PCR, making urgent the development of most effective LAMP protocols.