Climatic requirements of the eastern paralysis tick, Ixodes holocyclus, with a consideration of its possible geographic range up to 2090

Mortality, incidence and seasonality of canine and feline patients treated with tick antiserum in three far North Queensland veterinary clinics from 2000 to 2020

“…By comparison, one study had previously identified a decrease in reported canine and feline tick paralysis incidence in 2015, 9 though that study had proposed an overall reduction in reporting as a possible cause. Another study showed no decrease in tick paralysis incidence from 2015 onwards 28 . The cause of the decline seen in our study remains unexplained, however, due to isoxazolines becoming first available for dogs in Australia in January 2015 then cats in September 2018 (personal communication), a differential decline in numbers as observed in this study is to be expected.…”

“…Another study showed no decrease in tick paralysis incidence from 2015 onwards. 28 The cause of the decline seen in our study remains unexplained, however, due to isoxazolines becoming first available for dogs in Australia in January 2015 then cats in September 2018 (personal communication), a differential decline in numbers as observed in this study is to be expected. For this reason, isoxazoline availability is likely to be at least partially responsible for this decline.…”

“…The 2‐month earlier shift seen in our study remains unexplained, though may indicate that climate factors other than rainfall have a strong influence on tick paralysis incidence. Previous studies have found that factors including total moisture 28 as well as “annual precipitation, maximum temperature of the warmest month, temperature seasonality, temperature annual range, annual mean temperature and mean diurnal range,” 17 all help to predict tick paralysis distribution. Practically, the findings from our study mean that veterinarians in far north Queensland can probably expect a surge in tick paralysis cases if major rainfall was experienced 5–8 months prior, and August and September are typically the months with the highest caseload.…”

Climatic suitability of the eastern paralysis tick, Ixodes holocyclus, and its likely geographic distribution in the year 2050

“…Precisely which of these mechanisms I. holocyclus utilizes, if any at all, for its survival during diverse temperature and humidity conditions is not clearly known, but it is likely to involve multiple mechanisms. In this sense, the threshold values used by Teo et al 31 , based purely on laboratory observations may have been overly restrictive, leading to a conservative distributional estimate for this species. Further, because relationships between abiotic variables and species’ occurrences are fairly complex and highly dimensional, a physiological thresholding approach wherein values are set independently for different abiotic parameters may not capture species’ relationships with environments adequately.…”

“…Teo et al 31 assessed present and future potential distribution for I. holocyclus using both CLIMEX 32 , 33 and a novel, as-yet unpublished “climatic-range” approach to determine the suitability on monthly intervals. CLIMEX allows users to specify different upper and lower thresholds for climatic parameters, some of which were derived for their study from laboratory evaluations of I. holocyclus 34 .…”