Prevalence, Distribution, and Factors Associated with Vector-Borne Pathogen Infections in Pet Dogs from Different Geoclimatic Zones in Sri Lanka

Abstract

Vector-borne pathogens (VBPs) cause significant diseases in dogs in the tropics. In Sri Lanka, the scarce availability of previous studies on canine VBPs has hampered an accurate evaluation of their prevalence in pet dog populations. In this study, we collected demographic, clinical, and environmental data together with whole blood from 423 pet dogs from three geoclimatic zones in Sri Lanka. All blood samples were screened using a previously validated multiplex qPCR assay to detect the six most prevalent canine VBPs in tropical Asia. Multivariable logistic regression models were used to investigate environmental and host factors as predictors of VBP infections. Overall, 254 dogs (60.1%, 95% CI: 55.3–64.6%) were infected with one or more VBPs. Babesia gibsoni was the most prevalent VBP with 37.4% (95% CI: 32.7–42.2%) of dogs infected followed by Hepatozoon canis (21.04%, 95% CI: 17.25–25.24%), haemotropic mycoplasmas (10.2%, 95% CI: 7.5–13.4%), Babesia vogeli (5%, 95% CI: 3.2–7.5%), Ehrlichia canis (4.5%, 95% CI: 2.7–6.9%), and Anaplasma platys (3.8%, 95% CI: 2.12–6.1%). Predictors of VBP infections included tick infestation for H. canis ( p = 0.05 ) and A. platys ( p = 0.01 ), as well as age for B. gibsoni ( p = 0.01 ) and H. canis ( p = 0.05 ) infection. Local breed ( p = 0.004 ), male dogs ( p = 0.001 ) and flea infestation ( p = 0.04 ) were significantly associated with haemotropic mycoplasma infections suggesting direct-blood exchange through fighting and fleas as a possible means of transmission for these pathogens. Clinical results suggest that B. gibsoni and E. canis caused clinically significant disease, especially in exotic breeds such as German shepherds and Rottweilers compared to the local breeds ( p < 0.001 ). Measures such as educating pet dog owners on the importance of being vigilant on ectoparasite infestation of their pets, preventing pet dogs from interacting with stray or community dogs, and the compliant use of effective ectoparasiticides will be crucial for effective control of VBPs in pet dogs in Sri Lanka.

Metabarcoding using nanopore sequencing enables identification of diverse and zoonotic vector-borne pathogens from neglected regions: A case study investigating dogs from Bhutan

“…This study also identified many common canine VBPs that are typically found in temperate to tropical environments, including the bacterial pathogens A. platys, E. canis and M. haemocanis, as well as the apicomplexans B. gibsoni, B. vogeli and H. canis [ 4 , 31 , [82] , [83] , [84] ]. Many of these VBPs are transmitted by Rhipicephalus linnaei ticks, with pathogen species such as E. canis causing severe and potentially fatal infections in canines, whilst VBPs such as B. vogeli and A. platys typically only impact the health of puppies, or adults in the context of coinfections [ [85] , [86] , [87] , [88] ].…”

“…Many of these VBPs are transmitted by Rhipicephalus linnaei ticks, with pathogen species such as E. canis causing severe and potentially fatal infections in canines, whilst VBPs such as B. vogeli and A. platys typically only impact the health of puppies, or adults in the context of coinfections [ [85] , [86] , [87] , [88] ]. In addition, some of these pathogens may be transmitted non-vectorially, for example the potentially fatal piroplasmid B. gibsoni can be transmitted through fighting and aggressive interactions, whilst the transmission of canine haemotropic mycoplasmas is a debated field of research with strong evidence to suggest that these pathogens can be transmitted in the absence of arthropod vectors [ 83 , [89] , [90] , [91] ]. The identification of these canine VBPs in Bhutan is not surprising given that A. platys , Babesia spp., E. canis , and H. canis have been identified previously in northeastern India within regions directly bordering the south of Bhutan where our study was conducted [ 82 ].…”

“…Through this study's multivariable regression models canine age, sex and the presence of ectoparasites were identified as being significant predictors for canine VBP positivity ( Table 4 ). The finding that juvenile dogs had a decreased odds of being VBP positive is unsurprising given that many stray, owned and community dogs may never receive treatment for VBPs and therefore the chances of acquiring one of these typically lifelong infections increases with age [ 83 , 96 , 97 ]. The finding that male dogs had an increased odds of being VBP positive may be being driven by pathogens such as B. gibsoni that can also be acquired through blood exchange during fighting, in addition to vectorial transmission [ 83 , 89 ].…”

“…The finding that juvenile dogs had a decreased odds of being VBP positive is unsurprising given that many stray, owned and community dogs may never receive treatment for VBPs and therefore the chances of acquiring one of these typically lifelong infections increases with age [ 83 , 96 , 97 ]. The finding that male dogs had an increased odds of being VBP positive may be being driven by pathogens such as B. gibsoni that can also be acquired through blood exchange during fighting, in addition to vectorial transmission [ 83 , 89 ]. The high levels of B. gibsoni infection across all study sites (45%) in combination with increased aggressive interactions between male dogs may be behind this finding [ 98 , 99 ].…”