Predominant risk factors for tick-borne co-infections in hunting dogs from the USA

Abstract

Background Both incidence and geographical range of tick-borne disease has increased across the USA. Similar to people, dogs are hosts for Anaplasma spp., Babesia spp., Ehrlichia spp. and Borrelia burgdorferi. Dogs also share our homes and beds, making them both a sentinel for the ticks in our backyards but also increasing our exposure to ticks. Measures to better track, prevent, and/or treat tick-borne diseases in companion animals can lead to better control and prevention of human tick-borne disease. This study identifies demographic and co-infection risk factors for canine seropositivity to tick-borne infections in a cohort of hunting dogs across the USA. Results Human patterns of tick-borne disease co-infection in the USA have been predominantly driven by the geographical distribution of the tick vector. Dogs who tested seropositive for Anaplasma spp. were 1.40 times more likely (P = 0.0242) to also test seropositive for Babesia spp. and vice versa (1.60 times more likely, P = 0.0014). Dogs living in the West had 5% lower risk (P = 0.0001) for Ehrlichia spp. seropositivity compared to other regions. Controlling for age and Anaplasma spp. seroprevalence, dogs in all three other regions were 2.30 times more likely (P = 0.0216) to test seropositive for B. burgdorferi than dogs in the West. Dogs seropositive for B. burgdorferi were 1.60 times more likely (P = 0.0473) to be seropositive for Anaplasma spp. Conclusions Tick geographical distributions have a prominent impact on the regional distribution of hunting dog exposure to tick-borne diseases. Education concerning regional tick prevalence and disease risk is important for everyone, but particularly dog owners, regarding ticks in their region and protection from infection and co-infection of tick-borne pathogens as they travel or move with their dogs. Dogs are sentinel species for human exposure to ticks, and as such surveillance of canine tick-borne infections and understanding the probability that these infections might be seen together as co-infections helps predict emerging areas where people are more likely to be exposed as well.

Epidemiology of Vector-Borne Pathogens Among U.S. Government Working Dogs

“…burgdorferi prevalence was highest in the Northeast, as expected from prior nationwide study (Bowman et al 2009, Mahachi et al 2020, and owing in large part to vector species distributions. For Anaplasma spp., we found the highest prevalence in the Northeast ( p = 0.041) similar to findings in hunting dogs (Mahachi et al 2020). We found that the highest seroprevalence for antibodies to T. cruzi was in the southeastern United States, where there is a robust enzootic transmission cycle Montgomery 2009, Bern et al 2011), and the detected exposures in dogs outside this range likely occurred predeployment while training in the south (Meyers et al 2020b).…”

“…B. burgdorferi prevalence was highest in the Northeast, as expected from prior nationwide study (Bowman et al 2009, Mahachi et al 2020, and owing in large part to vector species distributions. For Anaplasma spp., we found the highest prevalence in the Northeast ( p = 0.041) similar to findings in hunting dogs (Mahachi et al 2020).…”

“…Working dogs are exposed to multiple vector-borne pathogens, including some of zoonotic concern. Their exposure to D. immitis, Anaplasma spp., and B. burgdorferi was lower than the reported prevalence of 1-3 million pet dogs nationwide (Bowman et al 2009) and lower than tickborne pathogens in a nationwide survey of hunting dogs (Mahachi et al 2020). In contrast, the Ehrlichia spp.…”

“…VBDs are caused by a diversity of pathogens, including protozoa, helminths, viruses, and bacteria, and can be transmitted by a range of arthropods, such as ticks, triatomines, fleas, phlebotomine sand flies, and mosquitoes. Exposure to vector-borne pathogens can be highly focal over space and time, and regions of risk may fluctuate as ideal conditions or reservoir host populations expand or decline (Hamer et al 2008, González et al 2010, Levi et al 2012, Levy et al 2014, Mahachi et al 2020. Accordingly, epidemiological data on vector-borne infections in dogs can be useful in identifying areas of risk.…”

Epidemiologic, Clinical and Immunological Consequences of Co-Infections during Canine Leishmaniosis

“…The prevalence rate was higher in the Northeastern U.S. (12.1%), where L. infantum is also enzootic among dogs [ 142 ]. Although the U.S., particularly the Eastern U.S., has relatively high seropositivity for canine borreliosis [ 143 ], there is currently limited published data on co-infection with CanL. In Europe, canine Borrelia spp.…”