Evaluation of infection by Borrelia sp. in domestic and wild mammals and ticks from the Catimbau National Park, Pernambuco

Abstract

Spirochetes in the genus Borrelia (Spirochaetes) are the etiological agents of two zoonotic diseases that have rodents as reservoirs: the Lyme disease, transmitted by ixodid ticks (Ixodidae), and tick-borne relapsing fever, which is transmitted mostly by argasid ticks (Argasidae). The information on the epidemiology of pathogens that affect animals is scarce, especially in places that have been barely studied, such as the Caatinga biome. Thus, in the present study, we aimed to detect DNA of Borrelia in the blood of wild and domestic mammals, as well as in ticks collected in the Catimbau National Park, State of Pernambuco, Northeast Brazil. Blood was collected from 77 captured wild animals belonging to Didelphidae (45), Echimyidae (21), Cricetidae (7), Caviidae (2), and Dasypodidae (2) families. Additionally, blood samples from 120 sheep, 119 goats, 70 dogs, and 47 cattle were obtained. A total of 286 ticks were collected in the environment and identified as Ornithodoros cf. tabajara (188) and Ornithodoros rietcorreai (98); in addition, larvae of Ornithodoros spp. were collected on Thrichomys laurentius (4 specimens) and Monodelphis domestica (1); larvae of O. rietcorreai on Didelphis albiventris (2) and T. laurentius (1); Amblyomma parvum on T. laurentius (4); Rhipicephalus sanguineus (sensu lato) on dogs (121) and Rhipicephalus microplus on cattle (47). All blood samples, 120 free-living ticks, 46 O. rietcorreai and 74 O. cf. tabajara, and 12 R. sanguineus s.l. were submitted to DNA extraction to perform a polymerase chain reaction (nested PCR), aiming at amplifying a fragment of the flaB gene present in all species of Borrelia. Only one free-living specimen of O. cf. tabajara (1.3%) was positive. Negative detections in mammals may be related to the absence of infection or the low concentration of the spirochetes in the hosts. The low prevalence of Borrelia found in ticks can be explained by the low infection rates that these spirochetes depict in their vectors. New studies focusing on the detection of antibodies, as well as on the sequencing and isolating Borrelia spp. should be encouraged for a better understanding of the epidemiology of these bacterial agents in the region.