Pyemotes ventricosus Dermatitis: A Case Report and an Extensive Review of Outbreaks and Clinical Cases

Abstract

(1) Background: Pyemotes ventricosus dermatitis, caused by free-living mites, could be difficult to diagnose since bites are painless and ectoparasites are not visible. We present an unpublished clinical case that occurred in Italy and an extensive review of clinical cases and outbreaks of Pyemotes species. (2) Methods: Case reports and outbreaks of Pyemotes spp. were searched for on Pubmed and Embase. Epidemiological and clinical data were analysed with descriptive statistics. (3) Results: In total, we found 40 case reports and 21 outbreaks to be considered in this review. The majority of cases involved young females, occurred in summer and were observed in Europe. Dermatitis was the most common clinical manifestation. Diagnosis was mainly based on risk factors. Treatment was based on topical steroids and antihistamine drugs. Regarding outbreaks, contact with grain or feed and exposure with infested furniture were the main risk factors. The mean number of involved patients were 69, with symptoms most commonly ending within a week. (4) Conclusions: Pyemotes ventricosus dermatitis is underreported, especially in countries like Africa and Central and South-America, since disease is self-limiting and comet sign is reported in a quarter of cases. The reduction in use of pesticides in agriculture could lead to an increased exposure to Pyemotes spp. in the future.

Trident-shaped Dermatitis in a Child

“…This mite is only just visible to the naked eye (length 0.16 mm (male) to 0.22 mm (female)). Human infestation occurs when infested materials (wood, wooden furniture, grain, feed, hay bales) are held or handled (2,3). Such infestation occurs in seasonal outbreaks and is more frequent during the summer, with a peak between May and September (4).…”

“…Cutaneous manifestations can be limited to a single lesion or manifest through multiple aspects (7). When a linear or serpiginous erythematous track called a "comet sign" is present (30% of cases) (2), the diagnosis is oriented toward Pyemotes ventricosus dermatitis and a clinical differentiation with other arthropod bites or stings (2,3,5,9). Usually there is 1 inflammatory track per lesion.…”

Microscopic Menaces: The Impact of Mites on Human Health

“…It is worth noting that chigger bites are sometimes confused for the bites of Pyemotes ventricosus, a white to yellow free-living ectoparasite that feeds on the larvae or nymphs of insects residing in seed, grain, straw, and wood. Pyemotes ventricosus displays very little host specificity, but if normal food sources are reduced, they may temporarily attack horses, cattle, and humans [57]. Utilizing its chelicerae, P. ventricosus injects a neurotoxin into the human epidermis, causing a skin eruption known as grain itch [58].…”

“…As the initial bite mimics that of chiggers, a characteristic linear serpiginous tract known as the 'comet sign' is pathognomonic for Pyemotes dermatitis. This sign may last up to 2-3 weeks after the bite and likely represents a local lymphangitis [57]. Oral antihistamines and corticosteroids have been recommended to prevent scratching and possible bacterial superinfection, and skin lesions typically self-resolve within 1-3 weeks [57][58][59][60][61].…”

“…This sign may last up to 2-3 weeks after the bite and likely represents a local lymphangitis [57]. Oral antihistamines and corticosteroids have been recommended to prevent scratching and possible bacterial superinfection, and skin lesions typically self-resolve within 1-3 weeks [57][58][59][60][61].…”