A group of 14 persons who live in an area of Australia endemic for the Australian paralysis tick,
Ixodes holocyclus, and who were involved in regularly collecting and handling these ticks, was examined for antibodies to tick-transmitted bacterial pathogens. Five (36%) had
[...] Read more.
A group of 14 persons who live in an area of Australia endemic for the Australian paralysis tick,
Ixodes holocyclus, and who were involved in regularly collecting and handling these ticks, was examined for antibodies to tick-transmitted bacterial pathogens. Five (36%) had antibodies to
Coxiella burnetii, the causative agent of Q fever and three (21%) had antibodies to spotted fever group (SFG) rickettsiae (
Rickettsia spp). None had antibodies to
Ehrlichia,
Anaplasma,
Orientia, or
Borrelia (Lymedisease) suggesting that they had not been exposed to these bacteria. A total of 149
I. holocyclus ticks were examined for the citrate synthase (
gltA) gene of the SFG rickettsiae and the
com1 gene of
C. burnetii; 23 (15.4%) ticks were positive for
Rickettsia spp. and 8 (5.6%) positive for
Coxiella spp. Sequencing of fragments of the
gltA gene and the 17 kDa antigen gene from a selection of the ticks showed 99% and 100% homology, respectively, to
Rickettsia australis, the bacterium causing Queenslandtick typhus. Thus, it appears that persons bitten by
I. holocyclus in NE NSW, Australia have an approximate one in six risk of being infected with
R. australis. Risks of Q fever were also high in this region but this may have been due to exposure by aerosol from the environment rather than by tick bite. A subset of 74
I. holocyclus ticks were further examined for DNA from
Borrelia spp.,
Anaplasma spp. and
Ehrlichia spp. but none was positive. Some of these recognised human bacterial pathogens associated with ticks may not be present in this Australian tick species from northeastern New South Wales.
Full article