Presumptive tick paralysis in 2 American Miniature horses in the United States.

RATIONALE: Tick paralysis has not been reported in horses in North America. CLINICAL FINDINGS: Two American Miniature horses were examined for progressive weakness and recumbency. Numerous ticks (Dermacentor variabilis) were found on both horses. Horse 1 was recumbent (grade 5/5 gait deficit) on presentation, whereas Horse 2 was standing but ataxic (grade 4/5 gait deficit) and tetraparetic. Both horses had decreased tongue and tail muscle tone, and had normal spinal reflexes. Cerebrospinal fluid cytology was normal. Equine herpesvirus-1 testing was negative. PERTINENT INTERVENTIONS: Ticks were removed within 24 hours of presentation. Both horses were treated topically with permethrin. Supportive care included fluid therapy, treatment for corneal ulceration, and frequent repositioning during recumbency. OUTCOME: Within 48 hours of tick removal, both horses were neurologically normal. CLINICAL RELEVANCE: Ours is the first reported case of presumptive tick paralysis in horses in North America. Although rare, tick paralysis should be considered in horses presented with acute-onset weakness progressing to recumbency.

A Comparative Meta-Analysis of Tick Paralysis in the United States and Australia.

CONTEXT: Tick paralysis is a neurotoxic envenoming that mimics polio and primarily afflicts children, especially in hyperendemic regions of the Western United States of America (US) and Eastern Australia. OBJECTIVE: To compare the epidemiology, clinical and electrodiagnostic manifestations, and outcomes of tick paralysis in the US versus Australia. METHODS: A comparative meta-analysis of the scientific literature was conducted using Internet search engines to identify confirmed cases of tick paralysis in the US and Australia. Continuous variables including age, time to tick removal, and duration of paralysis were analyzed for statistically significant differences by unpaired t-tests; and categorical variables including gender, regional distribution, tick vector, tick attachment site, and misdiagnosis were compared for statistically significant differences by chi-square or Fisher exact tests. RESULTS: Tick paralysis following ixodid tick bites occurred seasonally and sporadically in individuals and in more clusters of children than in adults of both sexes in urban and rural locations in North America and Australia. The case fatality rate for tick paralysis was low, and the proportion of misdiagnoses of tick paralysis as Guillain-Barré syndrome (GBS) was greater in the US than in Australia. Although electrodiagnostic manifestations were similar, the neurotoxidromes differed significantly with prolonged weakness and even residual neuromuscular paralysis following tick removal in Australian cases compared with US cases. DISCUSSION: Tick paralysis was a potentially lethal envenoming that occurred in children and adults in a seasonally and regionally predictable fashion. Tick paralysis was increasingly misdiagnosed as GBS during more recent reporting periods in the US. Such misdiagnoses often directed unnecessary therapies including central venous plasmapheresis with intravenous immunoglobulin G that delayed correct diagnosis and tick removal. CONCLUSION: Tick paralysis should be added to and quickly excluded from the differential diagnoses of acute ataxia with ascending flaccid paralysis, especially in children living in tick paralysis-endemic regions worldwide.

Child neurology: tick paralysis: a diagnosis not to miss.

A 4-year-old girl presented to our tertiary care hospital with a complaint of lower extremity weakness and unsteady gait for 2 days. She was able to pull herself to stand, but could not stand unsupported. She had no sensory symptoms or pain. She did not complain of any weakness in her arms, trunk, face, or neck. She had no bowel or bladder incontinence or retention. On presentation to the emergency room, she had minimal antigravity strength of the lower extremities, but normal strength elsewhere. In addition, she was areflexic in both lower extremities and had a wide-based, unsteady gait but no appendicular dysmetria or titubation. Sensory examination was normal.

Indications, durations and outcomes of mechanical ventilation in dogs and cats with tick paralysis caused by Ixodes holocyclus: 61 cases (2008-2011).

OBJECTIVES: The primary objectives of this research were to describe the indications for mechanical ventilation, the duration of mechanical ventilation and probability of survival in dogs and cats with respiratory failure induced by the Australian paralysis tick (Ixodes holocyclus). METHODS: A retrospective case series and a retrospective single cohort study were conducted using dogs and cats with tick paralysis requiring mechanical ventilation. An index of oxygenating performance of the lung (PF ratio of partial pressure of oxygen in arterial blood to fraction of inspired oxygen) was derived from arterial blood gas analysis; patients euthanased because of veterinary costs were identified and Kaplan-Meier survival analyses performed. RESULTS: In total, 36.6% of patients were ventilated because of hypoxaemia refractory to oxygen therapy, 38.3% because of hypoventilation, 18.3% because of unsustainable respiratory effort and 6.6% because of respiratory arrest. Median duration of mechanical ventilation was 23 h, median time hospitalised was 84 h and 63.9% of all patients requiring mechanical ventilation survived to discharge from the hospital. Survival probability increased to 75% when cases of cost-based euthanasia were right-censored rather than treated as deaths. The survival probability of patients ventilated because of hypoxaemia (52.6%) was significantly less than for those ventilated because of hypoventilation (90.5%). The first measured PF ratio after commencing mechanical ventilation was not significantly associated with survival probability. CONCLUSIONS: Dogs and cats with tick paralysis requiring mechanical ventilation to manage respiratory failure have reasonable survival probability. Dogs and cats requiring mechanical ventilation because of hypoventilation have a higher survival probability than those with oxygenation failure.

Tick paralysis in Australia caused by Ixodes holocyclus Neumann.

Ticks are obligate haematophagous ectoparasites of various animals, including humans, and are abundant in temperate and tropical zones around the world. They are the most important vectors for the pathogens causing disease in livestock and second only to mosquitoes as vectors of pathogens causing human disease. Ticks are formidable arachnids, capable of not only transmitting the pathogens involved in some infectious diseases but also of inducing allergies and causing toxicoses and paralysis, with possible fatal outcomes for the host. This review focuses on tick paralysis, the role of the Australian paralysis tick Ixodes holocyclus, and the role of toxin molecules from this species in causing paralysis in the host.

Pediatric tick paralysis: discussion of two cases and literature review.

This report describes two cases of tick paralysis in children diagnosed within a 3-month period (May-July 2002) in rural South Carolina. Differing presenting symptoms consisted of acute onset of ataxia in one patient and acute ascending paralysis in the other. Ticks were present on the scalp of both patients and were removed immediately. Both girls demonstrated improvement of signs and symptoms within hours and complete recovery within 24 hours of tick removal. The diagnosis of tick paralysis must be considered in any patient, particularly children, who present with either acute ataxia or acute ascending paralysis. As in any clinical encounter, careful history and thorough general and neurologic examinations must be performed to exclude the possibility of tick attachment.

Tick paralysis.

Tick paralysis results from inoculation of a toxin from tick salivary glands during a blood meal. It is a relatively uncommon neuromuscular disease with a higher prevalence among young girls, although older men who get exposed to ticks may also be affected. It typically presents as an acute ascending paralysis occurring a few days after tick attachment and may result in respiratory failure and death. Patients may report minor sensory symptoms but constitutional signs are usually absent. Deep tendon reflexes are usually hypoactive or absent and ophthalmoplegia and bulbar palsy can occur. Children may be ataxic. Electromyographic studies usually show a variable reduction in the amplitude of compound muscle action potentials but no abnormalities of repetitive nerve stimulation studies. These appear to result from a failure of acetylcholine release at the motor nerve terminal level. There may be subtle abnormalities of motor nerve conduction velocity and sensory action potentials. Removal of the tick results in the very rapid reversal of clinical and physiologic deficits, quicker with North American ticks than with the Ixodes species seen in Australia.

Tick paralysis.

Tick paralysis is a preventable cause of morbidity and death that, when diagnosed promptly, requires a simple low-cost intervention. The key to success is to consider tick paralysis in the differential diagnosis of ascending weakness, particularly in children, in geographic areas where this disease predominates.

Reactions to tick antitoxin serum and the role of atropine in treatment of dogs and cats with tick paralysis caused by Ixodes holocyclus: a pilot survey.

OBJECTIVE: To determine the incidence and nature of adverse reactions of dogs and cats to tick antitoxin serum and to re-evaluate the role of atropine in the treatment of tick paralysis. DESIGN: A retrospective questionnaire of veterinarians. PROCEDURE: Questionnaires were posted to 320 veterinarians in tick-endemic regions of Australia. Questions referred to dogs and cats treated for tick paralysis over a period of three years: the number treated, treatment protocols and adverse systemic reactions to tick antitoxin serum. Ninety completed questionnaires were returned and responses analysed. RESULTS: Veterinarians reported that approximately 3% of dogs exhibited adverse reactions immediately following treatment with tick antitoxin serum. Eighteen percent of these reactions were described as anaphylaxis, with the remaining 82% attributed to the Bezold-Jarisch reflex. Six percent of cats treated with tick antitoxin serum reacted adversely and the majority of reactions (63%) were ascribed to the Bezold-Jarisch reflex. Atropine was used routinely by 10% of responding veterinarians in the treatment of dogs and cats with tick paralysis. A similar number of veterinarians used atropine only in selected cases. Most veterinarians (76%) reported that they never used atropine in the treatment of tick paralysis in either dogs or cats. Within the survey population, premedication with atropine reduced the number of Bezold-Jarisch reactions following tick antitoxin administration approximately five-fold in dogs and four-fold in cats. CONCLUSIONS: Data from this pilot survey indicate that more cats than dogs have adverse systemic reactions to tick antitoxin serum and that the majority of these reactions in both dogs and cats could be related to the Bezold-Jarisch reflex. The number of reactions to tick antitoxin serum in dogs and cats could be significantly reduced by the routine use of atropine prior to administration of tick antitoxin serum.

Pearls and pitfalls in the diagnosis and management of neuromuscular junction disorders.

Myasthenia gravis (MG) is a common autoimmune disorder characterized by the presence of pathogenic antibodies directed against the acetylcholine receptor. Patients present with variable degrees and distribution of fluctuating weakness, at times life-threatening. Clinical manifestations, establishment of diagnosis, the natural history of MG, and therapeutic options are herein reviewed with an emphasis on pearls and pitfalls of clinical relevance. Far less common is Lambert-Eaton syndrome (the myasthenic syndrome), another autoimmune disorder due to the presence of antibodies directed against the PQ-type voltage-gated calcium channels. Clinical features and treatment issues of these and other disorders of neuromuscular transmission are reviewed.

Management of acute neuromuscular paralysis.

The diagnosis of acute neuromuscular paralysis includes central nervous system disorders, peripheral neuropathy, neuromuscular conduction block and muscle disease. Identification of the cause is largely a clinical problem but neurophysiological investigations are often essential and a few specific tests are helpful. The commonest cause is Guillain-Barré syndrome. Special precautions, especially monitoring vital capacity, must be taken to detect respiratory failure and avoid atelectasis and chest infection. In acute neuropathy there is an additional danger of cardiac arrhythmias which requires continuous electrocardiographic monitoring. Prolonged artificial ventilation should be supervised by a specialist multidisciplinary intensive care team. Specific treatment depends on the diagnosis: for Guillain-Barré syndrome, intravenous immunoglobulin is preferred to plasma exchange on the basis of similar efficacy but greater convenience; steroids are not helpful; for myasthenia gravis, anticholinesterases and prednisolone may need to be supplemented with intravenous immunoglobulin or plasma exchange; for polymyositis, steroids are the mainstay of treatment. During convalescence patients require understanding and support in coping with residual disability.

Tick paralysis in a red wolf.

A free-ranging male red wolf (Canis rufus) in North Carolina (USA), exhibiting paresis, anorexia and heavy tick infection was diagnosed with tick paralysis. The wolf recovered completely following the removal of all ticks. This is the first record of tick paralysis in the red wolf.

Tick-borne diseases in Australia.

Tick bites are a common problem in Australia and an important cause of morbidity in medical and veterinary practice. Complications include local inflammation and infection, paralysis and transmission of various pathogens. Over the past three decades, several new tick-borne diseases have been recognised both in Australia and overseas. The importance of these diseases has also increased, in part due to greater recreational activities occurring in tick infested areas. However, our understanding of the microbiology and epidemiology of many of these diseases is incomplete.

Tick paralysis in two llamas.

An 18-month-old sexually intact male llama and a 7-month-old female llama were examined because of weakness, lethargy, and recumbency. Both had signs of ascending motor paralysis with minimal or no afferent sensory loss. Tick paralysis was diagnosed on the basis of complete clinical recovery following removal of a single, attached and engorged female tick (Dermacentor andersoni) from each llama. The male llama recovered within a few hours after removal of the tick, but recovery in the female llama required several days. Serum creatine kinase activity was high in both llamas, possibly as a result of direct effects of toxin on muscles or nerves.