The First Reported Case of Mites, Suidasia pontifica, in the External Ear Canal of a Thai Agricultural Worker

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Yudthana Samung
Chamnarn Apiwathnasorn
Sutee Wonglakorn
Anon Phayakkaphon



The external auditory canal of a 57-year-old woman in Si Sa Ket Province was infested with > 20 mites. She complained of severe itching and a feeling of insects crawling in her right ear during the shallot (Allium ascalonicum) harvesting season. Mite specimens were collected from the patient’s ear and preserved in 90% alcohol. The remainders were removed by suction. The specimens were mounted with Hoyer’s medium and identified as the stored product mite, Suidasia pontifica. Possible sources of infestation were investigated by inspecting and collecting mites on dried chilies, shallots, and garlic bulbs, as well as house dust and other materials related to their cultivation, such as straw from the patient’s house. S. pontifica were recovered from house dust, shallots, and garlic bulbs. It was suspected that the mites entered the ear during the handling of these infested materials. This is the first report of stored product mites being implicated in occupational health in Thailand. Several species of mites have been reported to infest stored products; therefore, additional species of mites potentially injurious to agricultural workers are expected. An appropriate method of collecting mites, to permit correct identification, and for bionomics studies, is needed.

Keywords: mite; Suidasia pontifica; external auditory canal

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