Borrelia persica infection in rock hyraxes

Tick-borne relapsing fever (TBRF) is an acute infectious disease caused by arthropod-borne spirochetes of the genus Borrelia and characterized by recurrent episodes of fever. Borrelia persica, the causative agent of this disease in Israel, is transmitted by the argasid tick Ornithodoros tholozani. There is little information about the maintenance and possible vertebrate reservoirs of B. persica in nature, but the tick O. tholozani is known to feed on animals that enter its habitat in caves, rock crevices and shady environments. The rock hyrax (Procavia capensis) is commonly found in such habitats and may therefore serve as a reservoir host for O. tholozani. Blood and spleen samples from rock hyraxes were collected from twelve locations in Israel and the West Bank during 2009-2014 to test if these animals may be infected with B. persica. Real-time PCR targeting a segment of the flagellin (flaB) gene was initially used to detect B. persica. Positive samples were further analyzed by PCR, using a segment of the glycerophosphodiester phosphodiesterase (GlpQ) gene for additional confirmation. Borrelia species were identified by nucleotide sequence analysis and the copy number of Borrelia was quantified in blood and spleen samples based on the number of Borrelia 16S rRNA gene copies. A total of 112 hyraxes were examined, with both blood and spleen samples tested from 108 animals. Nine hyraxes were infected with B. persica, with a prevalence of 8%. Of these, two animals were positive for both blood and spleen samples, three only for blood and four only for the spleen. The number of DNA copies of Borrelia 16S rRNA was significantly higher in blood (5 × 10⁶ to 9.2 × 10⁸/ml blood) compared to spleen (2.1 × 10⁴ to 1.0 × 10⁶/ml). We conclude that rock hyraxes are possible reservoirs for B. persica because they have long lifespans and gregarious habits, share habitats with vector ticks, and are naturally infected with this spirochete. Further studies should be conducted in the future to evaluate the competence of hyraxes as reservoirs for B. persica infection.