Prevalence of vector-borne diseases in a sample of client-owned dogs on Santa Cruz in the Galápagos Islands: A pilot study

Abstract

A population of approximately 2500 dogs inhabits the island of Santa Cruz in the Galápagos Islands and many of these dogs freely roam the streets of the island in close proximity to people. The dog population receives minimal, if any, veterinary care or ectoparasite prophylaxis, leaving the majority of the dogs at risk for vector-borne infections such as Anaplasma platys, Borrelia burgdorferi, Dirofilaria immitis, Ehrlichia canis, and Ehrlichia ewingii. Data on the prevalence of vector-borne disease in dogs on the island of Santa Cruz are lacking. The current study served as a pilot investigation to estimate the prevalence of circulating antibodies or prevalence of circulating antigen specific to these vector-borne agents in client-owned dogs through the use of IDEXX SNAP® 4Dx® Plus Tests. Of the 37 dogs screened, the prevalence of antibodies to Ehrlichia spp. was the highest at 37.84% (95% CI=24.10, 54.90%), followed by a prevalence of 13.51% (95% CI=2.58, 24.44%) for antibodies to Anaplasma species. Prevalence of antibodies to Borrelia burgdorferi was 0% (95% CI=0, 0%), and prevalence of Dirofilaria immitis antigen was also 0% (95% CI=0, 0%). Tick infestation (RR=2.90; p=0.03) and sex (RR=2.20; p=0.05) were statistically significant risk factors for exposure to either Ehrlichia or Anaplasma species. Considering the zoonotic potential of these pathogens, reducing the prevalence of infection in the dog population is crucial in preventing transmission to the island's inhabitants and its tourists. Therefore, prevalence determined in the current study serves as a useful estimate for future surveillance and is valuable for evaluating the effectiveness of future control measures.