Antibodies against rickettsiae from spotted fever groups in horses from two mesoregions in the state of Santa Catarina, Brazil

Abstract

Bacteria of the Rickettsia genus are agents of Brazilian Spotted Fever (BSF), a zoonotic disease which is difficult to diagnose, evolves quickly and can result in death. Antibodies against Rickettsia spp. in horses were studied, by means of Indirect Immunofluorescence Assay (IFAT ≥64), in 150 blood samples taken from animals in two Santa Catarina mesoregions (Planalto Serrano and Vale do Itajaí). The overall occurrence of Rickettsia spp. antibodies in horses was 18.66%, with cross-reactivity occurring in all positive samples for at least two of the species tested. Separately, according to the species, 25 (16.66%) samples were positive for R. rickettsii, 15 (10%) for R. parkeri, 22 (14.66%) for R. amblyommii, 23 (15.33%) for R. rhipicephali, 16 (10.66%) for R. bellii and 19 (12.66%) for R. felis. Only two animals resulted in a conclusive serodiagnosis, one for R. bellii and the other for R. rickettsii, at maximum dilutions of 1:4096 and 1:512, respectively. The occurrence of antibodies against Rickettsia spp. in horses from two mesoregions in the state of Santa Catarina indicates the movement of BSF agents in these sentinel animals and confirms the importance of studying spotted fever in the state of Santa Catarina.

Preliminary Detection of Rickettsiae Using PCR Targeting OmpA Gene Among Dogs and Horses in Cairo, Egypt

“…in dog blood samples (8.8 %) in Nigeria. Meanwhile in horses, the prevalence of SFG rickettsioses in the present study (72.0 %) agreed with Lemos et al [11], Horta et al [36], Medeiros et al [31], Alves et al [37] and Riveros-Pinilla et al [14], who had detected rickettsiae serologically in horses using immunofluorescence. In addition, Vianna et al [38] and Pacheco et al [39] found that the prevalence rate of rickettsiae in horses ranged from 68 to 81 %.…”

“…Moreover, the same clinical signs in dogs were observed in horses except ocular signs. Lemos et al [11] and Medeiros et al [31] reported that the clinical manifestations of the disease in horses are rare. Concerning the rest of animals in the current study, they were apparently healthy (90 dogs and 83 horses).…”

Serological survey of Rickettsia in equids from Vale do Paraíba, São Paulo, Brazil, and their tick identification and molecular investigation of Rickettsia

“…This bacteria belongs to a rickettsial basal group that includes a variety of closely related agents infecting leeches, insects, protozoa, or even plants (Murray et al, 2016;Weinert et al, 2009), making it possible that these other organisms could be related to the seropositivity of R. bellii in the present study, a condition still not investigated. Medeiros et al (2013) demonstrated the occurrence of cross-reaction between different species of Rickettsia in horses. Positive serological responses in horses in areas with no tick exposure or negative serology in equines with tick exposure were described in different areas in Brazil (Batista et al, 2010;Pacheco et al, 2011).…”

“…in places where the incriminated vectors of the disease were not found, contrasting with places where there were positive arthropods in real-time PCR for Rickettsia spp. and no seropositive animals (Batista et al, 2010;Medeiros et al, 2013;Toledo et al, 2009).…”

“…The primary hosts for A. sculptum in endemic areas for BSF are capybaras (Hydrochoerus hydrochaeris) and horses (Equus caballus) (Aragão, 1936;Vieira et al, 2004). Equines are animals that can play a fundamental role in the epidemiological chain of BSF because they have free movement and can disseminate infected ticks, spreading the disease to different regions (Cardoso et al, 2006;Medeiros et al, 2013). Ueno et al (2016) evaluated horses after either intravenous inoculation of R. rickettsii or infestation by R. rickettsii-infected ticks, demonstrating that, in both cases, this bacteria was able to infect horses, inducing immune response, but without bacteremia and clinical manifestations of the disease.…”