The ‘other’ epidemic: canine ehrlichiosis in Australia

Abstract

Canine monocytic ehrlichiosis (Ehrlichia canis infection) is a serious tick-transmitted disease of dogs that was considered exotic to Australia until recently. The disease was first reported across northern and central Australia in 2020, with significant canine morbidity and mortalities observed at indigenous communities where dog numbers are high, ticks are superabundant, and tick prevention is scant. The date and location of the incursion are unknown, yet comparative genomic analysis suggest the Australian E. canis may have originated from Asia or the Middle East. Veterinarians nationwide are on alert for this notifiable disease since cases have been reported in southern locations as a consequence of moving infected dogs from endemic areas. Acute infections in dogs respond favourably to doxycycline therapy, however chronic disease results in bone marrow failure and death. Tick prophylaxis is key to preventing canine ehrlichiosis and is best achieved using products that repel and kill ticks before they attach. Although reports exist of E. canis as a zoonosis, there is no evidence that the strain involved in the current Australian outbreak poses risk to humans.

Perception of Ticks and Tick-Borne Diseases Worldwide

“…There is already evidence of biological changes to Australian ticks, whereby I. holocyclus has been identified as epizootic (temporarily prevalent) in the greater Melbourne area [250] with model predictions estimating that it could become climatically suitable for enzootic presence as early as 2030 [251]. On-going surveillance is also important for biosecurity efforts, as evident in the recent rapid spread of Ehrlichia canis [252]. Lastly, longitudinal studies will further elucidate the etiology and case definitions of human tick-borne diseases in Australia.…”