Field and laboratory studies in a Neotropical population of the spinose ear tick, Otobius megnini

Aural hematoma in lambs associated with Otobius megnini (Ixodida: Argasidae) infestation

In this report we described a case of aural hematomas in three lambs associated with Otobius megnini (Ixodida: Argasidae) infestation. From April to May 2021, five 3-month-old Hampshire cross lambs presented with unilateral aural hematomas. Upon otoscopic examination, engorged soft ticks (O. megnini) were observed in the external ear canals of three of the five lambs. The remaining two lambs had lesions consistent with infestation and were in a shared environment and deemed likely to have been infected. The treatment of all animals was based on the drainage of the serosanguinous fluid through an incision in the internal space of the ear pinna. Upon physical inspection of the entire flock (n = 310), O. megnini infestation was observed in one additional animal that did not have a hematoma. Following animal and environmental ectoparasiticide treatment with permethrin, no recurrences or additional cases of aural hematomas were observed in the flock in the following two-year period. To the authors' knowledge, this is the first description of aural hematomas in lambs associated with O. megnini infestation with successful recovery after surgery and off-label acaricide treatment.

Ticks infesting dogs and cats in North America: Biology, geographic distribution, and pathogen transmission

A diverse array of ixodid and argasid ticks infest dogs and cats in North America, resulting in skin lesions, blood loss, and disease. The ticks most commonly found on pets in this region are hard ticks of the genera Amblyomma, Dermacentor, Ixodes, and Rhipicephalus, as well as the more recently established Haemaphysalis longicornis. Soft tick genera, especially Otobius and Ornithodoros, are also reported from pets in some regions. In this review, we provide a summary of the complex and diverse life histories, distinct morphologies, and questing and feeding behaviors of the more common ticks of dogs and cats in North America with a focus on recent changes in geographic distribution. We also review pathogens of dogs and cats associated with the different tick species, some of which can cause serious, potentially fatal disease, and describe the zoonotic risk posed by ticks of pets. Understanding the natural history of ticks and the maintenance cycles responsible for providing an ongoing source of tick-borne infections is critical to effectively combatting the challenges ticks pose to the health of pets and people.

Putative Otobius megnini-associated clinical signs in horses in South Africa (2012-2018)

Otobius megnini has been associated with certain clinical conditions in horses in both California and Mexico. A number of cases similar to those described previously have been identified by the author in South Africa. This case report summarises these cases to demonstrate that the clinical condition occurs readily in South Africa and may be increasing in occurrence. The disease has minimal coverage in the literature making it more likely that a veterinarian, unfamiliar with the disease, will miss the diagnosis. The author would like to make veterinarians aware of this as a potential differential diagnosis. This study is a retrospective review of clinical data. Clinical records of patients with similar clinical signs and treatment were reviewed and grouped together as relevant cases for this case report. Ten cases of O. megnini associated neuromuscular dysfunction are reported, suggesting a link between the occurrence of the tick and the clinical condition. Clinical signs include third eyelid prolapse, localised muscle fasciculations, elevated heart rate and limb stamping. Serum chemistry changes commonly show increased aspartate aminotransferase and creatine kinase enzymes activities. The occurrence of the ticks within South Africa and the increasing number of cases presented demonstrate the need for more investigation into the pathophysiology of this condition.

The introduction and subsequent extinction of the camel tick Hyalomma (Euhyalomma) dromedarii (Acari, Ixodidae) in Australia, with a review of the introduction of foreign ticks to Australia

Historically, several tick taxonomists have reported Hyalomma aegyptium within Australia due to misidentifications. This has resulted in confusion relating to the occurrence of the genus Hyalomma within Australia. Based on the recent discovery of museum specimens of Hyalomma dromedarii, misidentified as H. aegyptium, the historical occurrence of H. dromedarii is reported for the first time within Australia, along with its apparent subsequent extinction. The introduction and naturalisation of foreign tick species into Australia is also reviewed.

Life cycle of Spinose ear tick, Otobius megnini (Acari: Argasidae) infesting the race horses in Nuwara Eliya, Sri Lanka

Otobius megnini infests mainly domesticated and wild animals and occasionally humans. It has been identified as an agent of human and horse otoacariasis in Sri Lanka. The number of nymphal stages in the life cycle of O. megnini varies from one to three in different geographic regions. The present study determined the life cycle of O. megnini infesting the racehorses in Nuwara Eliya. A tick colony was initiated from fully engorged nymphs collected from horses and maintained at 10°C, 22°C and 28°C. Immature stages were reared on New Zealand rabbits. Only the larvae weighing more than 0.9mg (84.9%) moulted to nymphs with a pre-moulting period of 5.6(±1.7) days. None of the larvae maintained at 10±1°C moulted. Larval survival was significantly higher at 28±1°C (44.2±4.3days) than at 22±1°C (35.6±9days). At 28±1°C, majority of nymphs (95.6%) weighing over 10mg moulted into adults within 12.5(±3.1) days. Nymphs kept at 10±1°C underwent diapause for 81.1(±72.0) days. Larger females (>13mg; 93.0%) laid eggs for of 44.6(±17.8) days with a mean pre-oviposition period of 10.3(±5.1) days. Females survived longer (369.8±128.3days) than males (210.4±54.1days; Student's t-test; t=5.9, p=0.001). Some females laid eggs without mating. Otobius megnini successfully completed the life cycle within 123days and has only one nymphal instar similar to the Neotropical population. Currently, O. megnini infestation is a serious problem to horses in the Nuwara Eliya racecourse and may pose a risk of spreading to dairy farms close by owing to its dynamic nature of the life cycle.

Human otoacariasis: Demographic and clinical outcomes in patients with ear-canal ticks and a review of literature

INTRODUCTION

Otoacariasis is a rare infestation of the ear canal, which affects the quality of life especially in rural areas. Different types of ticks and mites may cause otoacariasis. Although treatment of otoacariasis is simple, diseases transmitted through ticks and mites should be considered during diagnosis and treatment. Both local and systemic signs and symptoms of such diseases should be followed up.A literature review was conducted in PubMed using the following terms: "otoacariasis," "ticks," "mites," and "outer ear canal infestations." Demographic, radiologic, and treatment options were discussed. Treatment hints and pitfalls were also discussed with the literature review.

CONCLUSION

In this paper, we describe otoacariasis in humans and discuss the appropriate interventions.

Otoacariasis: demographic and clinical outcomes of patients with ticks in the ear canal

Introduction

Otoacariasis, the attachment of ticks and mites within the ear canal is a common phenomenon especially in rural areas.

Objective

To determine the clinical and demographic features of cases with detected ticks in the ear canal, which is a common health problem, and identify tick species.

Methods

Data of patients who had otoacariasis were collected. We also investigated all ticks at the Veterinary Department of Kafkas University.

Results

We present the data of patients with otoacariasis. All ticks were identified as otobius. Otobius ticks were found not related with any complications.

Conclusion

It is very important to detect ticks in the ear canal as they act as vector of some diseases. Identifying species of ticks may help clinicians to prevent further complications associated with vector-borne diseases.

Off-host collection methods of the Otobius megnini (Acari: Argasidae)

Otobius megnini (Dugès), often referred to as the spinose ear tick, is a one-host tick infesting the ear canal of a variety of ungulate species. The objective of this study was to develop sampling methods for collecting free-living stages of O. megnini and to collect preliminary data on habitat distribution. Sampling occurred during 2010 and 2011 at Fossil Rim Wildlife Center (FRWC) near Glen Rose, TX, where tick presence has been observed in the ears of a variety of ungulates. To sample for nonfeeding adult stage presence, a debris-filtering method was developed using screens of varying gauges. To sample host-seeking larval-stage tick presence, a carbon dioxide (CO2) trap was developed using compressed CO2 released through tubing along with cotton fabric used for tick attachment. Both methods proved successful with adults and larvae collected from animal shelters, with larvae also collected from oak leaf litter away from any structure. Locating both life stages off the host is the first crucial step toward the management of this tick species at facilities such as FRWC.