Tick paralysis induced by Ixodes gibbosus: enigmatic cases in domestic mammals from Cyprus

Anastasia Diakou, Angelique Foucault-Simonin, Giannakis Antoniou, Alejandro Cabezas-Cruz and Gábor Földvári

The manuscript by Diakou et al. deals with the cases of tick paralysis in Cyprus. Tick paralisis is a potentially fatal condition caused by neurotoxins produced by tick salivary glands, leading to a flaccid, ascending paralysis. Removing the ticks results in complete recovery. The most potent paralysis-inducing tick is Ixodes holocyclus in Australia, but at least 73 species worldwide can cause tick paralysis. The condition typically arises after several days of tick attachment, with higher toxin secretion during later feeding stages. Both hard ticks (Ixodidae) and soft tick larvae (Argasidae) can cause paralysis, primarily from female ticks in the repletion phase.

The required toxin concentration for paralysis depends on the tick species, developmental stage, and host size, resulting in variability in the number of ticks needed to induce paralysis. For instance, hundreds of nymphs or a single female tick can cause paralysis depending on these factors. Although the exact evolutionary purpose of these toxins is unclear, they may help ticks avoid removal by hindering host grooming. The molecular profile of tick toxins remains largely unknown, but there are similarities with proteins found in venomous animals.

Tick paralysis is frequently reported in Australia, the United States, and Canada but is rare in Europe. It is often underreported due to its non-reportable status. In Cyprus, cases are observed primarily in the Akamas peninsula, affecting free-ranging and semi-intensively reared small ruminants, as well as sporadically in dogs and cats. Cases exhibit periodic cycles of 3 and 7 years, with the 7-year cycles being more severe. The ticks responsible in Cyprus have been identified as Ixodes gibbosus, with significant animal losses reported during outbreaks.

Efforts to prevent tick paralysis in Cyprus involve using acaricides and restricting animal movement during high-risk periods. Future research is needed to understand the periodic nature of outbreaks and to characterize the specific toxins involved, potentially leading to vaccine development to mitigate animal losses in affected regions