Abstract
Blood samples were collected from 99 domestic dogs from the urban and rural areas of the Lábrea municipality, state of Amazonas, Brazil. Canine serum samples were tested by immunofluorescence assay against Rickettsia spp., which revealed that only 3.0% (1/33) and 7.6% (5/66) of the dogs from urban and rural areas, respectively, reacted positively to at least one Rickettsia species. DNA was extracted from canine blood and tested by a battery of PCR assays targeting protozoa of the genera Babesia and Hepatozoon, and bacteria of the genera Rickettsia and Ehrlichia and family Anaplasmataceae. All samples were negative in the PCR assays targeting the genera Babesia, Hepatozoon, Ehrlichia and Rickettsia. For Anaplasmataceae, 3% (1/33) and 39.4% (26/66) of the urban and rural dogs, respectively, yielded amplicons that generated DNA sequences 100% identical to the corresponding sequence of Wolbachia endosymbiont of Dirofilaria immitis. Because of these results, all canine DNA samples were further tested in a PCR assay targeting filarial nematodes, which was positive for 18.2% (6/33) and 57.6% (38/66) urban and rural dogs, respectively. Filarial-PCR products generated DNA sequences 100% identical to D. immitis. While tick-borne infections were rare in Lábrea, D. immitis infection rates were among the highest reported in South America.
Highlights
In recent years, there has been a substantial improvement in our knowledge of tick-borne diseases among domestic dogs in Brazil
Canine serosurvey in different parts of Brazil have indicated that dogs are infected with different spotted fever group (SFG)-Rickettsia species, such as R. rickettsii, Rickettsia parkeri, or Rickettsia amblyommii, all associated with ticks (PINTER et al, 2008; SAITO et al, 2008; MELO et al, 2011; SPOLIDORIO et al, 2013; SZABÓ et al, 2013)
These results largely contrast to all other regions of Brazil that have been investigated, where recent studies have indicated, by molecular methods, that a considerable proportion of the dogs was infected by E. canis, A. platys, B. vogeli, and/or H. canis (RAMOS et al, 2010; SPOLIDORIO et al, 2011; VIEIRA et al, 2011; COSTAJÚNIOR et al, 2012; SILVA et al, 2012; DEMONER et al, 2013)
Summary
There has been a substantial improvement in our knowledge of tick-borne diseases among domestic dogs in Brazil. A recent study described clinical illness in domestic dogs due to Rickettsia rickettsii, the agent of Rocky Mountain spotted fever (RMSF), for the first time in Brazil (LABRUNA et al, 2009). Domestic dogs have been considered excellent sentinels for infection by R. rickettsii and other spotted fever group (SFG) Rickettsia species in southeastern Brazil (SANGIONI et al, 2005; HORTA et al, 2007; PINTER et al, 2008). Canine serosurvey in different parts of Brazil have indicated that dogs are infected with different SFG-Rickettsia species, such as R. rickettsii, Rickettsia parkeri, or Rickettsia amblyommii, all associated with ticks (PINTER et al, 2008; SAITO et al, 2008; MELO et al, 2011; SPOLIDORIO et al, 2013; SZABÓ et al, 2013)
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