Immunomic Investigation of Holocyclotoxins to Produce the First Protective Anti-Venom Vaccine Against the Australian Paralysis Tick, Ixodes holocyclus

Venom producing animals are ubiquitously disseminated among vertebrates and invertebrates such as fish, snakes, scorpions, spiders, and ticks. Of the ~890 tick species worldwide, 27 have been confirmed to cause paralysis in mammalian hosts. The Australian paralysis tick (Ixodes holocyclus) is the most potent paralyzing tick species known. It is an indigenous three host tick species that secretes potent neurotoxins known as holocyclotoxins (HTs). Holocyclotoxins cause a severe and harmful toxicosis leading to a rapid flaccid paralysis which can result in death of susceptible hosts such as dogs. Antivenins are generally polyclonal antibody treatments developed in sheep, horses or camels to administer following bites from venomous creatures. Currently, the methods to prevent or treat tick paralysis relies upon chemical acaricide preventative treatments or prompt removal of all ticks attached to the host followed by the administration of a commercial tick-antiserum (TAS) respectively. However, these methods have several drawbacks such as poor efficacies, non-standardized dosages, adverse effects and are expensive to administer. Recently the I. holocyclus tick transcriptome from salivary glands and viscera reported a large family of 19 holocyclotoxins at 38-99% peptide sequence identities. A pilot trial demonstrated that correct folding of holocyclotoxins is needed to induce protection from paralysis. The immunogenicity of the holocyclotoxins were measured using commercial tick antiserum selecting HT2, HT4, HT8 and HT11 for inclusion into the novel cocktail vaccine. A further 4 HTs (HT1, HT12, HT14 and HT17) were added to the cocktail vaccine to ensure that the sequence variation among the HT protein family was encompassed in the formulation. A second trial comparing the cocktail of 8 HTs to a placebo group demonstrated complete protection from tick challenge. Here we report the first successful anti-venom vaccine protecting dogs from tick paralysis.

Acute flaccid paralysis in a neonate: tick bite a differential?

ABSTRACT Tick paralysis is an uncommon, noninfectious, neurologic syndrome characterized by acute ataxia and ascending paralysis mostly seen in children. Early recognition and prompt management with tick removal helps in complete recovery. If untreated, ascending paralysis can lead to respiratory failure and death in 10% of the cases. Tick paralysis is usually considered as a differential in all cases of acute ataxia and generalized weakness in children and adults but seldom in neonates due to its rarity and differences in clinical presentation in the newborn period. In neonates, tick paralysis may present only as generalized weakness and lethargy with poor feeding. Even though tick paralysis is common in children <10 years of age, it has never been reported in a neonate. We report a case of tick bite paralysis in a baby who presented in the neonatal period, and identification of the tick and its removal that helped in rapid recovery.

Isolated facial nerve palsy from intra-aural tick infestation – a case report

The incidence of tick infestation reported by ear-nose-throat outpatient clinics is high, though the exact reason is unknown. Affected patients generally recover well without any local or systemic sequelae. Tick-induced facial nerve palsy is less commonly reported in the literature. In this case report, we present our experience in managing a case of delayed isolated facial nerve palsy from intra-aural tick infestation in a child. The case highlights the possibility of late effects of tick paralysis occurring hours after tick removal. Close observation and awareness are crucial to detect any signs of neurotoxicity associated with tick infestation.

Apparent Ixodes tick paralysis in a cat from North America

Case summary A 2-year-old castrated male domestic longhair cat presented for acute, diffuse, flaccid paralysis. Thoracic and abdominal radiographs, biochemistry panel and complete blood count were unremarkable. Titers to Toxoplasma gondii, myasthenia gravis radioimmunoassay testing and creatinine kinase levels were within normal limits. The most likely differentials included acute toxicity (coral snake envenomation, organophosphate toxicity), botulism and, less likely, acute polyradiculoneuritis. A thorough physical examination revealed a single engorged tick attached to the ventral neck of the cat, which was later identified as an adult female Ixodes species. Topical fipronil and (S)-methoprene was administered. Over the next 48 h, the cat recovered full motor function and at 5 days post-tick removal the cat had resumed all normal activities. Relevance and novel information Tick paralysis is considered endemic in Australia by bites from, most commonly, the Ixodes holocyclus tick. However, this phenomenon is rarely reported in the USA. This is the first report of a domestic cat suffering from acute tick paralysis in North America.