Acute and chronic exposure to Tyrophagus putrescentiae induces allergic pulmonary response in a murine model

Effects of in-house and commercial extracts of the allergenic mite Tyrophagus putrescentiae on murine and human cell responses

Mites are among the major sources of domestic and occupational allergens worldwide, and continuous exposure to these allergens leads to chronic airway inflammation. One of the most allergenic species is the storage mite Tyrophagus putrescentiae (Schrank). Protein extracts are produced from this mite for tests that help the clinical diagnosis (via prick test), treatment, and monitoring of disease progression in patients who had positive results for allergic reactions. Therefore, the aim of the present study was to evaluate the cell viability of RAW 264.7 and L929 cells when exposed to in-house raw protein extracts of T. putrescentiae compared to a commercial product, as well as quantify TNF-α secretion by RAW 264.7. Additionally, this study quantified the effect of these extracts in IgE secretion in total blood of people affected by this mite. The study found similarity between the in-house extract and the commercial extract as they had equivalent TNF-α secretion. Additionally, viabilities of RAW 264.7 and L929 exposed to the in-house extract were compatible with viabilities of cells exposed to the commercial extract, with no cytotoxicity at the concentrations tested. Results corroborated the hypothesis that the extract produced in-house would be equivalent to the commercial extract in allergic patients when the IgE was quantified. This study is the first to show the cytotoxicity of T. putrescentiae extracts, and to provide a quantitative analysis of TNF-α and IgE.

Case report: Tyrophagus putrescentiae (Acari) attacking laying birds in conventional poultry houses

Tyrophagus putrescentiae (Schrank) (Acaridae) is one of the most allergenic mite species worldwide, and it particularly infests household environments, animal feed factories, and food factories. It has been the aim of several studies recently in the healthcare area due to its allergenic potential. However, there had been no records of this species attacking laying birds until this report. This is the first record of adverse reactions in animals triggered by infestations of this species. Therefore, the present study aims at describing the damages and symptomatology of T. putrescentiae infestations on commercial laying hens. Alopecia and dermatitis were symptoms exacerbated by T. putrescentiae infestation starting at 40 weeks old. The presence of this species on hens, as observed in the present study, might be directly related to the accumulation of food and poultry litter on these birds, in their cages, or in the vicinities. Hence, the results might be related to their feeding behavior, which consists of continuous supply of animal feed in these management systems. The present study provides an unprecedented record that reveals the importance and potential for emergency pest status of T. putrescentiae in the poultry industry. Its infestations in poultry houses probably required constant sanitary care and monitoring are required in order to prevent outbreaks of this mite.

Population growth of the stored product pest Tyrophagus putrescentiae (Acari: Acaridae) on environmentally and medically important fungi

The stored food mite Tyrophagus putrescentiae (Schrank) (Acari: Acaridae) has been associated with the presence of several fungal species. The aims of this work were to evaluate T. putrescentiae population growth associated to environmental and medically important fungal species to determine on which fungal species populations of T. putrescentiae performs best, and to evaluate their ability to disperse each fungal species. First, 24 fungal species were inoculated separately in Petri dishes containing Sabouraud agar medium. One week after inoculation, 50 mites were added to each plate. On the 28th evaluation day, mites and eggs were counted in each plate, and 50 mites randomly collected from each replicate were transferred to new plates containing only Sabouraud agar medium. Then, mites, eggs, and fungal population were evaluated in each plate on day 28 again. The highest population increases were on Trichophyton mentagrophytes, Alternaria sp., Microsporum gypseum, and Aspergillus chevalieri. With Fusarium guttiforme and the medically important fungi Microsporum canis, M. gypseum, T. mentagrophytes, and Sporothrix sp., mites were observed to feed on whole mycelium. Only eight fungal species were dispersed by T. putrescentiae to the new Petri dishes: Aspergillus clavatus, Candida tropicalis, Candida albicans, Fusarium guttiforme, Hyphopichia burtonii, Penicillium citrinum, Rhizophus azygosporus, and Trichophyton mentagrophytes. The best performance of T. putrescentiae was found feeding on F. guttiforme, P. citrinum, and T. mentagrophytes. In conclusion, T. putrescentiae successfully used fungi as a food source, and it proved to be an important tool for disseminating both environmental and medically important fungi.

Mite Fauna Assessment in Houses of Two distinct Socioeconomic Groups From Southern Brazil

House dust mites (HDM) are the main source of aeroallergens worldwide, yet epidemiological differences between socioeconomic factors in association with this medical condition have not been studied in the south region of Brazil. To assess the prevalence of HDM in two socioeconomically distinct populations of patients with allergic asthma or rhinitis, the differences between samples from houses of high-income families and low-income families were analyzed. Mite samples were collected between July and December 2015, in Porto Alegre, Brazil. The HDM were Dermatophagoides pteronyssinus and Dermatophagoides farinae (Hughes; Acari: Pyroglyphidae). Also, other non-pyroglyphid house mites were identified in dust samples: Tyrophagus putrescentiae (Schrank; Acari: Acaridae), Chortoglyphus arcuatus, and Cheyletus malaccensis. Identification of species was performed through morphological keys with a stereomicroscope and a phase optical microscope. A total of 104 homes was evaluated (low-income group: n = 53; high-income group, n = 51). We found a total of 721 mites, representing 11 species, in 93 (89%) houses. In the remaining houses, no mites were found. We observed no significant differences of species composition between the groups studied. However, the number of mites was significantly higher in the low-income group (P < 0.001). D. pteronyssinus was the predominant species detected, with 286 mites (39.6%). D. farinae was not detected in any sample. Our results show that living-rooms from low-income families present higher numbers of HDM.