Ticks are important ectoparasites of companion animals responsible for transmitting tick-borne pathogens1,2 and cause health problems such as tick paralysis ...
A survey of ticks (Acari: Ixodidae) of companion animals in Australia Telleasha Greay1, Charlotte Oskam1, Alexander Gofton1, Robert Rees2, Una Ryan1, and Peter Irwin1 1 Vector and Water-Borne Pathogen Research Group, School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia 2 Bayer Animal Health, Brisbane, Queensland, Australia
Introduction
Methods
Ticks are important ectoparasites of companion animals responsible for transmitting tick-borne pathogens1,2 and cause health problems such as tick paralysis, anaemia, dermatitis, and secondary infections during blood feeding3-6. Fortunately there are few tick-borne diseases of companion animals in Australia, including canine infectious cyclic thrombocytopenia7-8 and babesiosis9-12.
1. Study design
The study population of companion animal hosts included dogs, cats, and horses, nationwide, that presented to veterinary clinics, or ticks were sent to Murdoch University by owners.
2. Sample collection
Ticks were removed from hosts by veterinarians and owners, then preserved in 70% ethanol. Ticks were sent to Murdoch University by Bayer area managers and members of the general public.
Seventy tick species are present in Australia and 20 hard tick (ixodid) species have previously been recorded on dogs, cats, and horses in Australia.13 Many of these companion animal host records were obtained during 1950-7013 and include Rhipicephalus sanguineus, Ixodes holocyclus, and Haemaphysalis longicornis, which cause tick-borne diseases9,10,14.
3. Tick identification
Ticks were examined with a stereomicroscope and the instar and species were morphologically identified13,15 and recorded in an electronic database.
4. Sample mapping
Aims
The sample collection locations were geo-referenced using the open source software QGIS.
The objective of this research project was to assess the species of hard ticks (Acari: Ixodidae) that parasitise companion animals, including dogs, cats, and horses, during 2012-2015 across Australia.
Overall, n = 4,765 individual ticks of 11 species (Table 1) were identified from 837 hosts in 7/8 states and territories in Australia.
Amblyomma triguttatum
Ixodes myrmecobii
Bothriocroton sp.
Ixodes tasmani Rhipicephalus australis Rhipicephalus sanguineus
Haemaphysalis longicornis
Table 1. Number of ticks identified on companion animals hosts
Ixodes cornuatus Ixodes hirsti
Host
Kangaroo tick
Bothriocroton N/A sp. Haemaphysalis bancrofti Wallaby tick Haemaphysalis longicornis Bush tick
Ixodidae collection locations Majority of the collection locations (Figure 1) were within previously described enzootic ranges for the tick species, except for 32 records of R. sanguineus on dogs occurred in South Australia and Western Australia.
Legend
Haemaphysalis bancrofti
Amblyomma triguttatum
The database of tick identification results and sample information was generated and summarised with Microsoft® Excel® for Mac 2011 and IBM® SPSS® Statistics 2013 software.
Results
Morphological identification
Point displacement centre symbol
Ixodes holocyclus
Tick species Common name
5. Data analysis
Northern Territory
Host records
Total 10
0
15
25
14
0
0
14
5
1
22
Queensland
Table 2. Most common tick species identified on companion animals Host
0
15
1
207
28 420
Ixodes cornuatus
Southern paralysis tick
Ixodes hirsti
Hirst’s marsupial tick
0
1
0
1
Ixodes holocyclus
Paralysis tick
770
185
97
1,052
Ixodes myrmecobii
No common name
Ixodes tasmani
Common marsupial tick
Rhipicephalus australis
Australian cattle tick
Rhipicephalus sanguineus
Brown dog tick
0
Victoria
Tasmania
1
0
5
90
39
1
130
1
0
3
4
1
0
3,069
New South Wales
16
4
Overall %
Rhipicephalus sanguineus
73% (3,069/4,191)
Ixodes holocyclus
81% (185/229)
Haemaphysalis longicornis
60% (207/345)
Western Australia
South Australia
213
Tick species
Figure 1. Collection locations of ticks removed from dogs, cats, and horses in Australia. Each point represents a unique collection location for the corresponding tick species. Overlapping points were displaced with a point displacement renderer around a centre symbol (denoted in legend); point displacement distance was defined by number of map units (kilometres).
3,070
Novel host record One novel host record was obtained for I. myrmecobii, which was found on Felis catus (dometic cat) in Esperance, Western Australia.
Conclusion
Future Research Directions
This study is the first of its kind to be conducted in Australia and our results contribute to the understanding of the species and distribution of ticks that parasitise dogs, cats, and horses in Australia. The species that were most commonly found on these animals are well-known vectors of pathogens, or cause neurological disease. However, the vector competency of several species encountered in this study has not been widely investigated. Such knowledge is required to better understand the risks of tick-borne disease transmission to pets and potentially, to their owners.
This study is part of broader research investigating tick-borne pathogens of companion animals. Molecular methods, including next-generation sequencing will be used to screen for bacterial and protozoan pathogens in ticks collected from companion animals. Additionally, investigations of R. sanguineus overseas have found two paraphyletic lineages: the tropical lineage and the temperate lineage16, and these lineages may represent two differFigure 2. Scanning electron ent species17. These paraphyletic groupings will be micrograph of an R. sanguineus investigated across different climatic regions of Australia. male (ventral view). Preliminary data (Figure 2) suggests that the tropical lineage may be present in Perth, Western Australia.
References
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