Investigation of Debilitating Symptom Complexes Attributed to Ticks (DSCATT) in an Australian Cohort

There are some Australians with debilitating symptoms complexes attributed to ticks (DSCATT). Some attribute this illness to Lyme borreliosis, caused by members of the Borrelia burgdorferi sensu lato species group. Some also attribute this illness to tick-borne co-infections such as babesiosis. The existence of Lyme borreliosis in Australia is controversial as there is no evidence for the existence of these species in Australian ticks, while only one instance of possible locally-acquired babesiosis has been reported. A clinical study was performed investigating the demographics, epidemiology, symptomology and treatment approaches to DSCATT in Australia. The symptomology of DSCATT was found to be broad and non-specific. There was a lack of data to support that DSCATT is attributable to a tick bite. Those with DSCATT were found to be taking a range of antimicrobial drugs to treat their illness. In some cases, participants were taking multiple antimicrobials over extended periods. Some DSCATT participants reported probable adverse drug reactions that they attributed to a Jarish-Herxheimer reaction. Both those taking and not taking antimicrobials experienced a reduction in symptomology over time; therefore it is unclear whether antimicrobials are useful in the treatment of DSCATT. Evidence for babesiosis in the blood and serum of DSCATT participants was also investigated using microscopy, serological and molecular methods. There was no evidence for active Babesia infection. In nineteen DSCATT participants there was some evidence for previous exposure to Babesia; however this may be due to cross-reactivity. Molecular methods were used to investigate Babesia and Theileria in hard ticks collected from across Australia. Species known to infect humans were not identified. Novel Babesia and Theileria partial 18S rDNA sequences related to those known to infect marsupials were identified and phylogenetic analysis revealed that Australian piroplasms form monophyletic groups