Canine ehrlichiosis: prevalence and epidemiology in northeast Brazil

Abstract

Ehrlichiosis is a zoonotic disease that is caused by bacteria of the genus Ehrlichia. The aims of this study were to detect the presence of Ehrlichia spp. in the blood of dogs in Ituberá, Bahia, and to compare the sensitivities and specificities of blood smear, serological, and molecular examinations. Furthermore, this study identified factors associated with exposure to the agent in dogs in this locality. Blood samples were collected from 379 dogs and submitted for indirect immunofluorescent assay and polymerase chain reaction testing for the detection of Ehrlichia spp. antibodies and DNA, respectively. Additionally, a peripheral blood smear was obtained from the ear tip for parasite identification. Of the 379 animals, 12.4%, 32.7%, and 25.6% were identified as positive on the blood smear, serological, and molecular tests, respectively. The dogs positive in one of the three techniques were considered exposed (46.9%). Younger dogs and rural habitat were protective factors and presence of ticks and contact with other dogs were the risk factors associated with exposure to the agent. It was concluded that dogs of Ituberá have high positivity for Ehrlichia spp. and that the diagnostic methods used for detection are complementary.Keywords: Diagnosis, dog, Ehrlichia canis, Indirect Immunofluorescence, nested PCR. ResumoErliquiose é uma doença zoonótica causada por bactérias do gênero Ehrlichia. O objetivo desse estudo foi detectar a presença de Ehrlichia spp. no sangue de cães em Ituberá-BA, e comparar as sensibilidades e especificidades do esfregaço sanguíneo, e testes sorológico e molecular. Além disso, esse estudo identificou fatores associados com a exposição ao agente em cães desta localidade. Amostras de sangue foram coletadas de 379 cães e submetidas à Reação de Imunofluorescência Indireta e Reação em Cadeia de Polimerase para detecção de anticorpos e DNA de Ehrlichia spp., respectivamente. Adicionalmente, sangue periférico de ponta de orelha foi coletado para identificação do parasita. Dos 379 animais, 12,4%, 32,7% e 25,6% foram identificados como positivos no esfregaço sanguíneo, teste sorológico e molecular, respectivamente. Cães positivos em uma das três técnicas foram considerados expostos (46,9%). Cães mais novos e hábitat rural foram fatores de proteção e presença de carrapatos e contato com outros cães foram os fatores de risco associados à exposição ao agente. Foi concluído que, os cães do município de Ituberá têm alta positividade para Ehrlichia spp. e que os diferentes métodos diagnósticos utilizados para sua detecção são complementares.

Molecular diagnosis of Ehrlichia canis infection in dogs with uveitis

“…Previous studies on the prevalence of E. canis in canine populations evaluated using nested PCR in the southern regions of Bahia have reported lower incidences (CARVALHO et al, 2008;CARLOS et al, 2011;GUEDES et al, 2015). However, in the present study, we observed a higher prevalence; the values are closer to those observed by Oriá et al (2008), who found 66.67% positivity by using the indirect immunofluorescence test.…”

“…However, serological tests determine higher prevalence in studies, but cannot distinguish between pre-exposure and active infection, not always indicating that the animal is infected (MASSA et al, 2002;KOMNENOU et al, 2007;ORIÁ et al, 2008;GUEDES et al, 2015). Therefore, in animals with signs of uveitis, PCR provides accurate results because of the sensitivity and specificity of the test.…”

“…The positive control was dog blood tested positive for E. canis, as confirmed previously by sequencing (GUEDES et al, 2015). Ultrapure water was used as the negative control.…”

“…CME has been reported across all continents, but it is more frequently detected in temperate, tropical, and subtropical areas (DAGNONE et al, 2003;LABARTHE et al, 2003;RODRIGUEZ-VIVAS et al, 2005). In the state of Bahia, prevalence of 7.8% (CARVALHO et al, 2008), 11% (CARLOS et al, 2011), and 25.6% (GUEDES et al, 2015) has been reported by evaluating the canine populations with nested polymerase chain reaction (PCR).…”

Molecular epidemiology of Anaplasma platys, Ehrlichia canis and Babesia vogeli in stray dogs in Paraná, Brazil

“…Seroprevalence for E. canis was also high in the city of Alvorada do Sul (42.4%), central north region of Paraná (Vieira et al 2013a). CME is endemic to several Brazilian states, and E. canis frequency is high in São Paulo (40%) (Ueno et al 2009), Mato Grosso do Sul (45%) (Sousa et al 2013), Bahia (25.6%) (Guedes et al 2015), Pernambuco (57%) (Ramos et al 2009) and Paraíba (25%) (Rotondano et al 2015). Nevertheless, in Rio Grande do Sul, the occurrence of this rickettsia is low or null, although R. sanguineus is present (Saito et al 2008, Lasta et al 2013.…”