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Pyemotes ventricosus mites are an uncommon cause of pruritic dermatitis seen most commonly in occupational exposure, prominently found in professionals such as farmers, landscapers, and factory workers who work with grains, wheat, dried beans, or grasses. The clinical description of the rash has typically been described as papular, erythematous, with a central vesicular lesion. We describe a case of Pyemotes dermatitis with an atypical clinical presentation. A 30-year-old man presented with pruritic, umbilicated papules, which involved his right lateral trunk and upper thigh leading to the submitted clinical impression of molloscum contagiosum. A biopsy of the skin was taken, and fragments of arthropod consistent with P. ventricosus were identified within umbilicated indentations of skin. The patient subsequently admitted to the onset of the rash immediately after carrying bales of straw while supporting each bale with his right side. The possibility of Pyemotes dermatitis mimicking a poxvirus-like eruption should be considered when encountering an unusual umbilicated papular eruption in the appropriate patient with occupational exposure.

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Importance Although Pyemotes species have been known to cause dermatitis, recent reports are rare. During the past 30 years, only 3 outbreaks of dermatitis caused by Pyemotes ventricosus have been reported. Objective To analyze the causative agent of skin changes in employees of a company that produced herbal medicines. Design, Setting, and Participants This case series includes 18 patients (8 men, 10 women; mean age, 44 years) who contracted unusual dermatitis after an occupational exposure in July and August of 2012 while working for a company that produced herbal medicines. The patients were examined at the Lower Silesia Regional Centre of Occupational Medicine in Wroclaw, Poland. Exposures Workers weighed and packed 1 part of the Helichrysum arenarium herb. Main Outcomes and Measures We hypothesized the causative agent to be P ventricosus . An examination of the herbal specimens for ectoparasites confirmed the diagnosis. Results Initially 16 employees developed pruritic skin changes. Skin lesions with pruritic vesicles on an erythematous base with surrounding swelling and edema were observed. Several employees also developed a flulike illness. After 44 days, 2 new employees presented with the same skin changes. The analysis of working conditions showed that the same part of the H arenarium herb was weighed and packed at that time. Conclusions and Relevance We found that changing the time when the herbs were weighed and abandoning gas fumigation containing methyl bromide resulted in the recurrence of an almost forgotten disease.

Background Skin diseases caused by mites and insects living in domestic environments have been rarely systematically studied. Objectives To study patients with dermatitis induced by arthropods in domestic environment describing their clinical features, isolating culprit arthropods and relating the clinical features to the parasitological data. Methods The study was performed in 105 subjects with clinical and anamnestic data compatible with the differential diagnosis of ectoparasitoses in domestic environments. Clinical data and arthropods findings obtained by indoor dust direct examination were studied. Results Indoor dust direct examination demonstrated possible arthropods infestation in 98 subjects (93.3%), more frequently mites (56.1%) (mainly Pyemotes ventricosus and Glycyphagus domesticus) than insects (43.9%) (mainly Formicidae and Bethylidae). Strophulus (46.9%) and urticaria-like eruption (36.7%) in upper limbs and trunk with severe extent were prevalent. Itch was mostly severe (66.3%) and continuous (55.1%). Ectoparasitoses occurred frequently with acute course in summer (44.9%) and spring (30.6%). Conclusions Possible correlation between clinical and aetiological diagnosis of arthropods ectoparasitoses in domestic environments needs the close cooperation between dermatologist and parasitologist. This is crucial to successfully and definitely resolve skin lesions by eradicating the factors favouring infestation.

In 1976 and 1977 the larval population of T. oleisuga reached two peaks: a. June 1976, July 77, b. October 1976, 77. The pupation was delayed in 1976 due to the more severe winter. The crashes in the winter population were therefore delayed. These two crashes conformed well with the peaks of the empty tunnels. The delay of the peak of living larvae (tunnels from May/June 1976 to June/ July 1977) was due to the increase of the number of Khamassin days in May-July 1976. The population of Pyemotes ventricosus reached its peaks at: a. April-May 1976, 1977, b. Sept.–Oct. 76, Nov.-Dec. 1977. These two peaks do not conform with the peaks of the host. This shows that the weather conditions and not the mite control the fluctuations in the pest population. The activities of ovipositing adults in artificial wounds reached a peak in May-July and decreased till Dec. 1977. Adults prefer wounds of 1–56 days old over wounds 57–70 days old. The polyvoltinism of this insect is confirmed by: Ovipositing activities of the adults from May-Dec, - its short life cycle, - tunnels are continuously emptied for pupation underground during the summer months, - the gradual increase of living larval population in October 1976, 1977. Zusammenfassung Zur Haufigkeit der Gallmucke, Thomasiniana oleisuga Targ. (Dipt., Itonididae) sowie ihrer Parasiten und Predatoren in Amman, Jordanien In beiden Untersuchungsjahren 1976 und 1977 erreichte die Larvendichte von T. oleisuga 2 Maxima: im Juni/Juli sowie Oktober. Infolge des vorausgegangenen strengen Winters waren die Verpuppung 1976 sowie demzufolge auch der Mortalitatsverlauf der Winterpopulation verzogert. Dies ging mit den Maxima der leeren Minen in den Stengeln parallel. Die Verzogerung des Maximums an Larven (Mai/Juni 1976 auf Juni/Juli 1977) beruhte auf dem Anstieg der Zahl der “Khamassin”-Tage im Mai/Juli 1976. Die Population der Raubmilbe Pyemotes ventricosus erreichte ihre maximale Dichte im April/Mai 1976 und 1977 sowie im Sept./Oktober 1976 bzw. Nov./Dez. 1977. Diese 2 Spitzen gingen nicht mit jenen des Wirtes konform. Das zeigt, das die Witterungsbedingungen und nicht die Milben die Population des Schadlings regulieren. Die Aktivitat eierlegender Mucken in kunstlichen Wunden erreichte ihren Hohepunkt im Mai/Juni und nahm dann bis zum Dezember ab. Die ♀♀ zogen 1–56 Tage alte Wunden den 57–70 Tage alten vor. Der Polyvoltinismus von T. oleisuga wird bestatigt durch: die Eiablage von Mai bis Dezember, - den kurzen Lebenszyklus, - die kontinuierliche Leerung der Minen zwecks Verpuppung wahrend der Sommermonate sowie den gradualen Anstieg der Zahl lebender Larven im Oktober.

The spread of Pyemotes ventricosus (Newport, 1850) was observed during three years in 460 houses where dermatoses of environmental origin were reported. The period of highest mite spread was from May to August. This parasitic infestation was among the most important causes of human dermatitis in summer.

To the Editor: Recently, Pascal Del Giudice et al. published an interesting article (1) about dermatitis in France caused by Pyemotes ventricosus in which they highlight the presence of the comet sign in a number of their patients. It is, they assert, a sign that because of its peculiarity could be useful for diagnosing this type of dermatitis in outbreaks and sporadic cases. Some years ago, we studied 3 outbreaks (with >100 cases) of dermatitis caused by P. ventricosus parasitic mites in Castellon, Spain, produced by different infected materials (2). When we published the results, we concentrated on the epidemiologic characteristics and the discovery of the mite; perhaps we paid too little attention to the appearance of the lesions, of which we did not provide images. Nevertheless, we also observed the descriptions by Del Giudice et al., which we now show in the Figure. In 2 patients (Figure, panels A and B), the comet sign can be clearly assessed; the patients were 2 women who had had direct contact with the infected material against their legs. The other patient (Figure, panel C) displayed 56 macules with 1 pruritic central vesicle. We did not observe facial lesions on any of the case-patients (but we did observe lesions on the necks of some patients). Figure Photographs of 3 persons with skin lesions of Pyemotes dermatitis during the same outbreak in Castellon, Spain, showing the comet sign in 2 affected women (panels A, B), and macular form of the lesions in 1 of the affected investigators (panel ... Our data coincided with those of the French study and reinforce the specificity of this dermatologic sign. However, this was not the only coincidence; cases also occurred among the investigators after contact with the infected material in each of the outbreaks. Perhaps both signs may characteristic this dermatitis: the comet sign and “the sign of the infected investigators” of the outbreaks.

This article 'Occurrence of a Predatory Mite Pyemotes Ventricosus on Sitotroga cerealella Oliv' appeared in the International Rice Research Newsletter series, created by the International Rice Research Institute (IRRI). The primary objective of this publication was to expedite communication among scientists concerned with the development of improved technology for rice and for rice based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land scarce nations in the world.

A 1981 outbreak of dermatitis in Austin, Tex, was traced to occupational exposure to wheat infested with the straw itch mite, Pyemotes ventricosus ; the wheat was being sold for decorative purposes by an imported-goods store located on the second floor of a large, modern, shopping mall complex. In addition to an extensive varicelliform skin eruption, one employee also had chills, fever, malaise, diarrhea, and anorexia associated with her exposure to these mites. The straw itch mite has been associated with several large epidemics of dermatitis during the 19th and 20th centuries. This outbreak is the third reported in Texas since 1961. Physicians should consider the possibility of straw itch mite infestations of products brought into the home or places of employment when they observe patients with a varicelliform or chigger-bite-like dermatitis, which may be accompanied by constitutional symptoms. ( JAMA 1982;247:2821-2823)