Rickettsia Detected in the Reptile Tick Bothriocroton hydrosauri from the Lizard Tiliqua rugosa in South Australia.

Harriet Whiley,Michael Gardner,John Stenos,Kirstin Ross,Michael Taylor,Stephen Graves,Georgie Custance

doi:10.3390/pathogens5020041

Harriet Whiley, Michael Gardner + Show 5 more

Open Access

https://doi.org/10.3390/pathogens5020041

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Abstract

Rickettsiosis is a potentially fatal tick borne disease. It is caused by the obligate intracellular bacteria Rickettsia, which is transferred to humans through salivary excretions of ticks during the biting process. Globally, the incidence of tick-borne diseases is increasing; as such, there is a need for a greater understanding of tick–host interactions to create more informed risk management strategies. Flinders Island spotted fever rickettsioses has been identified throughout Australia (Tasmania, South Australia, Queensland and Torres Strait Islands) with possible identifications in Thailand, Sri Lanka and Italy. Flinders Island spotted fever is thought to be spread through tick bites and the reptile tick Bothriocroton hydrosauri has been implicated as a vector in this transmission. This study used qPCR to assay Bothriocroton hydrosauri ticks collected from Tiliqua rugosa (sleepy lizard) hosts on mainland South Australia near where spotted fever cases have been identified. We report that, although we discovered Rickettsia in all tick samples, it was not Rickettsia honei. This study is the first to use PCR to positively identify Rickettsia from South Australian Bothriocroton hydrosauri ticks collected from Tiliqua rugosa (sleepy lizard) hosts. These findings suggest that B. hydrosauri may be a vector of multiple Rickettsia spp. Also as all 41 tested B. hydrosauri ticks were positive for Rickettsia this indicates an extremely high prevalence within the studied area in South Australia.

Highlights

Worldwide, the incidence of tick borne disease is increasing [1]
R. honei has not been previously identified from South Australian B. hydrosauri but is considered likely to occur in this tick species due to the proximity of the disease and the ticks
All of the 41 B. hydrosauri ticks tested were positive for Rickettsia DNA

Summary

Introduction

The incidence of tick borne disease is increasing [1]. This includes tick borne rickettsiosis which is caused by the obligate intracellular bacteria belonging to the Rickettsia genus [2]. Stenos et al [9] examined reptile ticks Bothriocroton hydrosauri from Flinders Island, Australia, and detected Rickettsia via PCR in 63% (29/46) ticks. In South Australia, there have been confirmed cases of R. honei isolated from patients in the same geographical location known for B. hydrosauri [10]. R. honei has not been previously identified from South Australian B. hydrosauri but is considered likely to occur in this tick species due to the proximity of the disease and the ticks.

Results and Discussion

Sample Collection

DNA Extraction

PCR Detection

Sequencing of Positive Samples

Conclusions