Intra-aural tick bite causing unilateral facial nerve palsy in 29 cases over 16 years in Kandy, Sri Lanka: is rickettsial aetiology possible?

Abstract

BackgroundOver the last two decades intra-aural tick infestation (otoacariasis) has been a common occurrence in the hilly central region in Sri Lanka. Very occasional detection of isolated unilateral facial nerve palsy associated with otoacariasis attributed to toxin damage of the nerve prompted us to study the clinico-epidemiology and aetio-pathology of the problem.MethodsAll cases having isolated unilateral facial nerve palsy associated with otoacariasis presented to, Ear Nose and Throat clinic at General Hospital Kandy, Sri Lanka from 2001 to 2016 were included in the study. The facial palsies were assessed with nerve conduction studies and, harvested ticks were identified.ResultsThere were 29 patients with mean age of 46 years (range 22–76 years) with male to female ratio of 1:1.9. First 12 patients without specific treatment took 1–55 months for recovery and 4 had axonal degeneration. Last 5 patients were treated with doxycycline and recovered in 4 weeks. They had strong sero-conversion of immunofluorescence antibodies against spotted fever rickettsioses and the tick harvested from the last patient was PCR positive for rickettsial DNA. Identified ticks belonged to Dermacentor, Amblyomma, Rhipicephalus and Hyalomma species.ConclusionsOn contrary to popular toxin theory, we were able to demonstrate treatable rickettsial aetio-pathology as the cause of otoacariasis associated lower motor facial palsy in Sri Lanka.

Isolated third nerve palsy complicating Rickettsial fever: A rare neurological complication

“…Facial nerve palsy, vestibulocochlear nerve palsy, abducens palsy and a single case of isolated third nerve palsy have been reported [7,8,9,10,11]. A series of lower motor facial nerve palsy due to intra-aural tick bites with associated rickettsial infection has been reported in Sri Lanka [12].…”

Rickettsial infections of the central nervous system

“…The most common neurological manifestations reported in rickettsial infections include meningitis, encephalitis, and acute disseminated encephalomyelitis [5]. However, unilateral facial nerve palsy [6], cerebral infarction [7], or visual loss [8] have also been diagnosed. Therefore, it is critical to enhance the awareness of physicians worldwide on CNS rickettsial infections (CNS R).…”

Rickettsioses in Sri Lanka – A mini review

“…38 Another neurological manifestation that has been attributed to rickettsial infections is facial nerve palsy following intra-aural tick bites. 39 Joint involvement leads to many patients presenting with joint pains of large and small joints. This has been reported from patients with spotted fever rickettsioses.…”

“…47 Ticks of the Rhipicephalus species removed from a patient with demonstrable sero conversion to rickettsial antibodies has been shown to have rickettsial DNA. 39 A number of ticks associated with rickettsial infections have been recovered from both humans (autocariasis) and animals in Sri Lanka. Interestingly, these ticks are known to reside on domestic as well as wild animals.…”