Tick-borne zoonotic agents infecting horses from an urban area in Midwestern Brazil: epidemiological and hematological features

Abstract

The emergence of tick-borne diseases has been reported as a serious problem in public health worldwide and many aspects of its epidemiology and effects on the health of its hosts are unclear. We aimed to perform an epidemiological study of tick-borne zoonotic Rickettsia , Borrelia , and Anaplasmataceae in horses from Midwestern Brazil. We also evaluated whether Borrelia spp. and Anaplasmataceae may be associated with hematological disorders in the sampled animals. Blood and serum samples as well as ticks were collected from 262 horses. Serum samples were used to perform serological tests, and hematological analyses were made using whole blood. Furthermore, DNA extracted from whole blood and ticks was used for molecular tests. Campo Grande is enzootic for tick-borne studied bacteria, since we found an overall exposure of 59.9% of the sampled horses, 28.7% of them presented co-exposure. Seropositivity rates of 20.6% for Borrelia spp., 25.6% for Rickettsia spp., and 31.6% for Anaplasmataceae were found in the sampled horses. Considering both molecular and serological tests for Borrelia spp., the infection rate was 48.0% (126/262). None of the tested horses showed molecular positivity for Anaplasma phagocytophilum . The horses sampled displayed 7.2% of parasitism by ixodid ticks in single and coinfestations. We did not find DNA of any studied bacteria in the sampled ticks. Positive horses for Borrelia spp. and Anaplasmataceae agents displayed leukopenia, monocytopenia, and lymphopenia. Together, our results suggest that horses may play a role as sentinel host for zoonotic bacteria and Borrelia spp. and Anaplasmataceae agents can impair the health of horses.

Serological exposure of spotted fever group Rickettsia in capybaras (Hydrochoerus hydrochaeris) from urban parks in Campo Grande, Brazilian Midwest

“…Campo Grande, in the Midwest region of Brazil, should be monitored since because (i) capybaras that live in urban green areas are highly exposed to Rickettsia of the SFG; (ii) these capybaras presented high tick infestations; (iii) the tick species found parasitizing capybaras have anthropophilic habits; (iv) urban green fragments areas of CG have an intense people flow 2 ; (v) A. dubitatum parasitizing capybaras were found to be infected by Rickettsia of the SFG in the studied areas 5 ; and (vi) Campos et al 6 noticed that 25.6% of 262 sampled horses in the CG were exposed to rickettsia agents of the SFG. Owing to the latent risk of transmission, a surveillance and contingency plan for rickettsioses should be considered for the study area.…”

“…Rickettsia , belonging to the spotted fever group (SFG), has been found in CG and its surroundings, showing molecular evidence for R. parkeri in A. sculptum 3 , R. parkeri strain Atlantic rainforest in A. ovale 4 , R. parkeri , R. africae , and R. sibirica in A. dubitatum 5 . Furthermore, Campos et al 6 reported a general seroprevalence of Rickettsia spp. in 25.6% of horses sampled in the CG (n=262); 19.8% were exposed to R. rickettsii , 16.7% to R. parkeri , and 17.5% to R. amblyommatis .…”

“…We used an indirect immunofluorescence antibody test (IFAT) to detect IgG antibodies against Rickettsia spp. in the SFG according to Campos et al 6 . We used slides containing crude antigens derived from Rickettsia isolates from R. rickettsii strain Taiacu, R. parkeri strain At24, and R. amblyommatis strain Ac37, which are available at the Laboratory of Parasitic Diseases (University of São Paulo, Department of Preventive Veterinary Medicine and Animal Health).…”