High seroprevalence of selected vector-borne pathogens in dogs from Saipan, Northern Mariana Islands.

Abstract

Background: Canine vector-borne diseases (CVBDs) are illnesses caused by pathogens transmitted by blood-feeding arthropods such as ticks and mosquitoes. Many CVBDs, including dirofilariosis, anaplasmosis, and ehrlichiosis, are globally distributed and may cause a variety of clinical signs in dogs. Several CVBD agents are zoonotic, making epidemiological surveillance a joint veterinary and public health effort. In this study, we determined the seropositivity of four pathogens from dogs on Saipan, Northern Mariana Islands, a US Commonwealth located in the western Pacific Ocean.

Methods: Blood samples (n = 443) were collected from client-owned, owner surrendered, and shelter dogs that participated in an island-wide spay-and-neuter event in 2023. All samples were assessed using a commercial, point-of-care enzyme-linked immunosorbent assay (ELISA) test (SNAP^® 4Dx^® Plus, IDEXX Laboratory, Westbrook, Maine, USA) to detect the Dirofilaria immitis antigen and antibodies against Ehrlichia spp., Anaplasma spp., and Borrelia burgdorferi sensu lato. Risk factors were assessed for each pathogen through a univariate analysis, followed by a multivariable logistic regression.

Results: Overall, 66.1% (n = 300/443) of the dogs tested positive for at least one pathogen, with the highest prevalence observed for Ehrlichia spp. (58.0%; n = 246/443), followed by Anaplasma spp. (43.1%; n = 184/443) and D. immitis (14.8%; n = 63/443). Among the dogs with a single pathogen detected (30.9%; n = 137/443), Ehrlichia spp. was most prevalent (64.9%; n = 89/137), followed by Anaplasma spp. (23.3%; n = 32/137) and D. immitis (11.6%; n = 16/137). For co-detection of two or more pathogens (36.7%; n = 163/443), Ehrlichia spp. + Anaplasma spp. presented the highest frequency (70.5%; n = 115/163), followed by Ehrlichia spp. + D. immitis (6.7%; n = 11/163), Anaplasma spp. + D. immitis (3.6%; n = 6/163), and Ehrlichia spp. + Anaplasma spp. + D. immitis (19.0%; n = 31/163). Age (P = < 0.001), residing district (P = 0.001), and ownership status (P = < 0.001) were significantly associated with D. immitis positive status in a univariable analysis. Age (P = < 0.001), residing district (P = 0.177), and ownership status (P = 0.014) were significant in a univariable analysis with Ehrlichia spp. as an outcome. Finally, Anaplasma spp. had a significant association with ownership status (P = < 0.001) as a risk factor in a univariable analysis.

Conclusions: This study shows high seropositivity for CVBPs in a dog population living in a poorly studied area. The results of this study suggest that strategies for the prevention and control of these CVBDs should be reinforced on the Island of Saipan.