Australian ticks through time and place

Abstract

In the Australian small animal veterinary context, the paralysis tick Ixodes holocyclus and the brown dog tick Rhipicephalus sanguineus are the most significant ticks of medical and economic significance. Of the two, I. holocyclus is the most medically and veterinary significant tick along the eastern coastline of Australia. It is known to cause fatal and flaccid paralysis and allergic reactions in humans and animals. In regional Australia, R. sanguineus is problematic due to its endophilic nature and affinity for parasitising canids. They are known disease vectors and high tick burdens are associated with clinical anaemia. This thesis aimed to determine the effect of location and time on the small animal veterinary and medically significant ticks and their bacterial profile. Nymph ticks were retrieved from the environment in Sydney, NSW and adult ticks were retrieved from dogs in Sydney, and regional NSW. A systematic survey was completed to provide an update to the current identity of ticks in metropolitan Sydney, and regional NSW via morphological and molecular means. Next generation sequencing (NGS) technology was used to determine the microbiota of I. holocyclus and whether it differs between life stages and location in NSW. The microbial diversity of I. holocyclus across various localities in NSW was established using a NGS approach for nymph and adult I. holocyclus at various locations along the eastern coastline of NSW. To investigate the identity and distribution of brown dog ticks across Australia, a systematic survey was conducted to determine the current distribution. Further, due to the ambiguity surrounding the morphology of brown dog ticks, it was necessary to determine their genetic identity in Australia. As brown dog ticks were first described in Australia in 1896, a retrospective study was conducted on Australian museum material of “R. sanguineus”, allowing for the confirmation of the past and present identities of brown dog ticks across Australia.