Tick-borne infectious diseases in Australia
The incidence of tick-related medical problems in Australia is largely unknown. Appropriate diagnostic tests are not always available and, of all tick-related diseases, only Q fever is notifiable.1 Anecdotally, however, many patients present to their doctor after a tick bite. This narrative review focuses on tick-borne infections but also touches briefly on other medical problems caused by tick bites.
There are many different species of ticks in Australia. Only a few species are known to bite humans, and the microbes within these particular ticks — viruses, bacteria or protozoa — are potential causes of infection in humans who are bitten (Box).
However, the mere detection of a potential human pathogen in a tick does not mean that it can be transmitted to a person when bitten. To be transmitted to a person, the microbe must be present in the salivary glands of the tick while it is feeding.
Most studies of Australian ticks to date have investigated the whole microbiome of the tick and not their salivary glands specifically. Some pathogens may be present in the tick faeces, but transmission would require the patient to scratch the faeces into their skin — an unlikely scenario in most cases.
To be confident that a microbe in a tick is responsible for a particular illness in a patient bitten by that…