House dust and storage mite contamination of dry dog food stored in open bags and sealed boxes in 10 domestic households

Label-free proteomic analysis reveals differentially expressed Wolbachia proteins in Tyrophagus putrescentiae: Mite allergens and markers reflecting population-related proteome differences

Tyrophagus putrescentiae is an astigmatid mite of great economic, medical and veterinary importance. The microbiome, especially intracellular bacteria, may affect allergy/allergen expression. We targeted Wolbachia proteins, allergen comparisons and markers in Wolbachia-mite interactions in three mite populations. A decoy database was constructed by proteogenomics using the T. putrescentiae draft genome, Wolbachia transcriptome assembly and current T. putrescentiae-related sequences in GenBank. Among thousands of mite-derived proteins, 18 Wolbachia proteins were reliably identified. We suggest that peroxiredoxin, bacterioferritin, ankyrin repeat domain-containing protein and DegQ family serine endoprotease indicate a higher-level bacterium-bacterium-host interaction. We produced evidence that the host-Wolbachia interaction is modulated through pattern recognition receptors (PRRs), mannose-binding lectins/mannose receptors, the cholinergic anti-inflammatory pathway with TNF-α, and others. We observed Tyr p 3 suppression in mites with Wolbachia, linking trypsin to PRR modulation. Nine out of the 12 current WHO/IUIS official allergens were reliably identified, but the remaining three allergens, Tyr p 1, 8 and 35, were detected as only trace hits. This study provides numerous markers for further Wolbachia-host interaction research. For accuracy, mite allergens should be considered according to abundance in species, but mite populations/strains, as well as their microbiome structure, may be key factors. SIGNIFICANCE: The astigmatid mites occurring in homes are significant producers of allergens that are highly dangerous to humans and domesticated animals. Mites are tightly associated with microorganisms that affect their biology and consequently allergy signatures. Mite populations were found to be infected with certain intracellular bacteria, but some populations lacked an intracellular bacterium. Our previous research showed that some populations of Tyrophagus putrescentiae are infected with Wolbachia, but some populations host additional bacteria of interest. Thus, there are not only interactions between the mites and Wolbachia but also likely an additional level of interaction that can be found in the interaction between different bacteria in the mites. These "higher-level" signatures and consequences that bacteria affect, including allergen production, are not understood in mites. In this study, we identified Wolbachia-specific proteins in mites for the first time. This study provides Wolbachia- and mite-derived markers that can be clues for describing "higher-level" mite-bacterium-bacterium interactions. Indeed, the microbiome contribution to allergies can potentially be derived directly from bacterial proteins, especially if they are abundant.

A Survey among Dog and Cat Owners on Pet Food Storage and Preservation in the Households

BACKGROUND

Pet food storage plays a crucial role in maintaining the nutritional and sensory properties of purchased products over time.

METHODS

An online survey was developed to collect data regarding owners' storage habits for both commercial and home-made diets.

RESULTS

The questionnaire was completed by 1545 dog owners and 676 cat owners. Pet and owner age played roles in the choice of the type of diet (commercial vs. home-cooked vs. raw meat-based) adopted. Kibble feeders (75.7%) usually bought one (50.1%) or two (24.6%) packages at a time, and most pets (64.4%) took a minimum four weeks to consume an entire bag. Almost half of the owners (43.5%) used a container to store pet food (plastic bins for 79.5%). Pet food was commonly stored in the kitchen (45.1%) and not exposed to direct light (94.5%); 23.6% of the kibble feeders said it might be exposed to high temperatures. Most commercial pet food feeders (67.3%) considered preservatives a potential health risk for pets. Among homemade diet feeders, 38.6% stored fish oil at room temperature.

CONCLUSIONS

Pet owners should be educated in proper food storage management when receiving feeding instructions from veterinarians. More comprehensive information on the nature and importance of additives in pet food should be promoted by manufacturers.

The Role of Dust Mites in Allergy

House dust mites are an unsurpassed cause of atopic sensitization and allergic illness throughout the world. The major allergenic dust mites Dermatophagoides pteronyssinus, Dermatophagoides farinae, Euroglyphus maynei, and Blomia tropicalis are eight-legged members of the Arachnid class. Their approximately 3-month lifespan comprises egg, larval, protonymph, tritonymph, and adult stages, with adults, about one fourth to one third of a millimeter in size, being at the threshold of visibility. The geographic and seasonal distributions of dust mites are determined by their need for adequate humidity, while their distribution within substrates is further determined by their avoidance of light. By contacting the epithelium of the eyes, nose, lower airways, skin, and gut, the allergen-containing particles of dust mites can induce sensitization and atopic symptoms in those organs. Various mite allergens, contained primarily in mite fecal particles but also in shed mite exoskeletons and decaying mite body fragments, have properties that include proteolytic activity, homology with the lipopolysaccharide-binding component of Toll-like receptor 4, homology with other invertebrate tropomyosins, and chitin-cleaving and chitin-binding activity. Mite proteases have direct epithelial effects including the breaching of tight junctions and the stimulation of protease-activated receptors, the latter inducing pruritus, epithelial dysfunction, and cytokine release. Other components, including chitin, unmethylated mite and bacterial DNA, and endotoxin, activate pattern recognition receptors of the innate immune system and act as adjuvants promoting sensitization to mite and other allergens. Clinical conditions resulting from mite sensitization and exposure include rhinitis, sinusitis, conjunctivitis, asthma, and atopic dermatitis. Systemic allergy symptoms can also occur from the ingestion of cross-reacting invertebrates, such as shrimp or snail, or from the accidental ingestion of mite-contaminated foods. Beyond their direct importance as a major allergen source, an understanding of dust mites leads to insights into the nature of atopy and of allergic sensitization in general.

Chemical profile, characterization and acaricidal activity of essential oils of three plant species and their nanoemulsions against Tyrophagus putrescentiae, a stored-food mite

Essential oils of Ocimum basilicum (L.), Achillea fragrantissima (Forssk.) and Achillea santolina (L.) were obtained by hydrodistillation and analyzed using gas chromatography (GC) and GC/mass spectrometry (MS). Oil-in-water nanoemulsions (10% active ingredient) were prepared through a high-energy (ultrasonication) emulsification process. Nanoemulsions were characterized by viscosity, pH, thermodynamic stability, droplet size, polydispersity index (PDI) and scanning electron microscopy (SEM) measurements. The plant oils and their nanoemulsions showed considerable acaricidal activity against the mold mite, Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae). In a contact toxicity bioassay and 48 h post treatment, O. basilicum oil was the most toxic, followed by A. fragrantissima and A. santolina, where LC₅₀ values were 8.4, 14.1 and 21.8 µl/cm², respectively. LC₅₀ for benzyl benzoate, a standard acaricide was 9.8 µl/cm². Upon fumigation, responses also varied according to the test oil. Based on the 48-h LC₅₀ values, the same manner of activity was also observed, where O. basilicum was the most toxic followed by A. fragrantissima and A. santolina. When prepared as nanoemulsions (particle size from 78.5 to 104.6) and tested as fumigants, toxicity of the oils was increased drastically with LC₅₀ values of 2.2, 4.7, and 9.6 µl/l air for O. basilicum, A. fragrantissima and A. santolina, respectively. The oils showed a moderate to strong residual acaricidal activity, where O. basilicum oil was the most effective. The results suggest that appropriate nanoemulsions containing the tested oils can be developed to control T. putrescentiae after the required toxicological assessments.

Critically Appraised Topic on Adverse Food Reactions of Companion Animals (8): Storage Mites in Commercial Pet foods

Background

Dogs with year-round atopic dermatitis are often sensitized to Dermatophagoides house dust mites (HDM). Storage mites (SM) are known to grow on cereal-rich foods. Tyrophagus SM can exacerbate clinical signs of allergy in laboratory dogs sensitized to HDM. Consequently, atopic dogs with high-levels of HDM-specific IgE are likely to have a flare of signs after eating a food contaminated with SM; the development of such flares would lead to a false positive diagnosis of food allergy. Herein, we reviewed the published evidence about the growth of SM on commercial dry pet foods.

Results

We searched two databases on January 25, 2019 for articles providing original information on the growth of SM on commercial dog foods. We found ten articles, five reporting results of laboratory experiments and five from field studies. Storage mites, especially Tyrophagus putrescentiae, can multiply on protein- and fat-rich dog foods. The population growth is higher when the initial mite density is high and when kibbles are crushed. When storage conditions lead to the overgrowth of molds on the kibbles, the mite proliferation is higher. Storage mites do not bore holes in food packages but invade bags via defective seals. In the field, SM contamination usually is undetectable in newly-opened commercial dog foods, and, if present, their number is low. When newly-purchased bags are stored in temperate conditions indoors, little overgrowth—if any—of SM occurs. However, when kept in environmental conditions with higher temperature and humidity, Tyrophagus mites will enter and proliferate in sealed food packages.

Conclusions

Commercial dry pet foods should be kept indoors and sealed to decrease the risk of contamination with SM. When performing dietary restriction (elimination) and provocation trials for the diagnosis of food allergies in dogs, it seems preferable to choose newly-purchased bags—of both original and testing diets—to reduce the probability of their contamination with SM, especially Tyrophagus putrescentiae. In case of doubt about the presence of SM in any of these foods, one should perform food challenges with single home-cooked ingredients. Storage mite contamination might lead to an erroneous diagnosis of food allergy in HDM-sensitized dogs.

Use of Lard, Food Grade Propylene Glycol, and Polysaccharides in Infused Nets to Control Tyrophagus putrescentiae (Schrank; Sarcoptiformes: Acaridae) Infestation on Dry Cured Hams

Tyrophagus putrescentiae (Schrank) is controlled in the U.S. dry cured ham industry with methyl bromide (MB) fumigation. However, MB fumigation is being phased out of use since it is an ozone depleting substance. The objective of this research was to evaluate ham nets that were infused with lard, propylene glycol (PG) and polysaccharide coating for their efficacy at controlling mite infestations on dry cured ham cubes from hams that were aged for 4 to 6 mo. Results indicated that fewer T. putrescentiae (P < 0.05) were on ham cubes with treated nets containing PG when compared to the number of mites on ham cubes with untreated nets over 10 wk of storage. Lard infused nets without PG did not decrease the mite population (P > 0.05). The net without coating slowed the growth and reproduction of T. putrescentiae since net controls had fewer mites (P < 0.05) than controls without nets. Fungi were not present on ham cubes that were treated with PG-containing nets over 10 wk of storage with a few exceptions. In conclusion, lard and xanthan gum, or carrageenan + propylene glycol alginate treated nets containing the medium concentration of PG effectively inhibited mite reproduction and fungal growth on dry cured ham and could potentially be used in an integrated pest management program to control mites on dry cured hams.

Feces Derived Allergens of Tyrophagus putrescentiae Reared on Dried Dog Food and Evidence of the Strong Nutritional Interaction between the Mite and Bacillus cereus Producing Protease Bacillolysins and Exo-chitinases

Tyrophagus putrescentiae (Schrank, 1781) is an emerging source of allergens in stored products and homes. Feces proteases are the major allergens of astigmatid mites (Acari: Acaridida). In addition, the mites are carriers of microorganisms and microbial adjuvant compounds that stimulate innate signaling pathways. We sought to analyze the mite feces proteome, proteolytic activities, and mite-bacterial interaction in dry dog food (DDF). Proteomic methods comprising enzymatic and zymographic analysis of proteases and 2D-E-MS/MS were performed. The highest protease activity was assigned to trypsin-like proteases; lower activity was assigned to chymotrypsin-like proteases, and the cysteine protease cathepsin B-like had very low activity. The 2D-E-MS/MS proteomic analysis identified mite trypsin allergen Tyr p3, fatty acid-binding protein Tyr p13 and putative mite allergens ferritin (Grp 30) and (poly)ubiquitins. Tyr p3 was detected at different positions of the 2D-E. It indicates presence of zymogen at basic pI, and mature-enzyme form and enzyme fragment at acidic pI. Bacillolysins (neutral and alkaline proteases) of Bacillus cereus symbiont can contribute to the protease activity of the mite extract. The bacterial exo-chitinases likely contribute to degradation of mite exuviae, mite bodies or food boluses consisting of chitin, including the peritrophic membrane. Thus, the chitinases disrupt the feces and facilitate release of the allergens. B. cereus was isolated and identified based on amplification and sequencing of 16S rRNA and motB genes. B. cereus was added into high-fat, high-protein (DDF) and low-fat, low-protein (flour) diets to 1 and 5% (w/w), and the diets palatability was evaluated in 21-day population growth test. The supplementation of diet with B. cereus significantly suppressed population growth and the suppressive effect was higher in the high-fat, high-protein diet than in the low-fat, low-protein food. Thus, B. cereus has to coexist with the mite in balance to be beneficial for the mite. The mite-B. cereus symbiosis can be beneficial-suppressive at some level. The results increase the veterinary and medical importance of the allergens detected in feces. The B. cereus enzymes/toxins are important components of mite allergens. The strong symbiotic association of T. putrescentiae with B. cereus in DDF was indicated.

Dry Dog Food Integrity and Mite Strain Influence the Density-Dependent Growth of the Stored-Product Mite Tyrophagus putrescentiae (Acari: Acaridida)

The infestation of foodstuffs by mites is connected to health risks and economic losses. The cosmopolitan stored-product mite Tyrophagus putrescentiae (Schrank, 1781) is an emerging and predominant pest of dry dog food. In this study, the influences on mite population growth of 1) the different dry dog food kernels present in the package; 2) the integrity of the dry dog food kernel, whether intact or crushed; 3) the initial population density of 10 or 100 specimens; and 4) the four mite strains used were investigated under laboratory conditions. The population growth tests were performed for 28 d at 85% relative humidity and 25°C. The intrinsic growth rates of the mites were compared. The population growth was higher on the brown and green kernels than on the red and white kernels. The kernel integrity affected the population growth, and the integrity effect was highly influenced by the initial mite population density. The mites showed density-dependent growth in three of the four mite strains tested. The initial population density changed the population growth ranking among the mite strains, thereby indicating strain-specific density-dependent growth. The results of this study have important implications for predictive models of stored-product mite populations in dry dog food. One practical recommendation is that the growth of mites should be considered with regard to the mite strains and according to the strain-specific density dependent growth. Next, the integrity of the kernels should be maintained because disrupted or crushed kernels promote increases in mite populations.

Population Growth of the Generalist Mite Tyrophagus putrescentiae (Acari: Acaridida) Following Adaptation to High- or Low-Fat and High- or Low-Protein Diets and the Effect of Dietary Switch

Tyrophagus putrescentiae (Schrank, 1781) is a cosmopolitan generalist feeder that prefers foodstuffs of high-fat and high-protein content. Our aim was to investigate the population growth of T. putrescentiae after long-term nutritional adaptation to two distinct diets that are commonly infested in the synanthropic environment. Crushed dry dog food kernels provided a high-fat, high-protein, and low-carbohydrate diet, whereas wholemeal spelt flour provided a low-protein, low-fat, and high-carbohydrate diet. After >6 mo of nutritional adaptation, each of the two populations were used in two 28-d population growth tests: one that mites remained on their adaptation diet (homogenous diet treatment) and one that mites underwent a dietary switch (dietary switch treatment). Dietary treatment, nutritional adaptation, and their interaction all significantly influenced population growth. The homogenous diet treatment showed 7.5 times higher growth on the dog food diet than on flour. In the dietary switch, flour-adapted mites switching to dog food experienced five times greater population growth than the flour-adapted mites remained on flour, whereas the dog food-adapted population showed a 2.8-fold decrease in population growth when transferred to the flour. A comparison of means between the two dietary switch treatments showed a 1.9-fold higher population growth after flour-adapted mites were shifted to dog food than when the dog food-adapted mites were shifted to flour. We demonstrated that T. putrescentiae is able survive and reproduce for many generations on dry dog food and flour with different levels of success. High-fat and -protein food accelerated T. putrescentiae population growth compared with the high-carbohydrate diet.

Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA)

Background

In 2010, the International Task Force on Canine Atopic Dermatitis (now International Committee on Allergic Diseases of Animals, ICADA) published the first consensus guidelines for the treatment of atopic dermatitis (AD) in dogs. This is the first 5-year minor update of this document.

Results

The treatment of acute flares of AD should involve the search for, and then elimination of, the cause of the flares, bathing with mild shampoos, and controlling pruritus and skin lesions with interventions that include topical and/or oral glucocorticoids or oclacitinib. For chronic canine AD, the first steps in management are the identification and avoidance of flare factors, as well as ensuring that there is adequate skin and coat hygiene and care; this might include more frequent bathing and possibly increasing essential fatty acid intake. The medications currently most effective in reducing chronic pruritus and skin lesions are topical and oral glucocorticoids, oral ciclosporin, oral oclacitinib, and, where available, injectable recombinant interferons. Allergen-specific immunotherapy and proactive intermittent topical glucocorticoid applications are the only interventions likely to prevent or delay the recurrence of flares of AD.

Conclusions

This first 5-year minor update of the international consensus guidelines for treatment of AD in dogs further establishes that the treatment of this disease is multifaceted, and that interventions should be combined for a proven (or likely) optimal benefit. Importantly, treatment plans are likely to vary between dogs and, for the same dog, between times when the disease is at different stages.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0514-6) contains supplementary material, which is available to authorized users.

Stored product mites (Acari: Astigmata) infesting food in various types of packaging

From 2008 to 2014, stored product mites have been reported from prepackaged dried food on the market in the Czech Republic. The infestation was by Carpoglyphus lactis (L.) in dried fruits and Tyrophagus putrescentiae (Schrank) in dog feed. The infestation is presumably caused by poor protection of the packages. We compared various packaging methods for their resistance to mites using dried apricots and dog feed in laboratory experiments. The trial packages included nine different plastic films, monofilm, duplex and triplex, and one type of plastic cup (ten replicates per packaging type). All packaging materials are available on the Czech market for dried food products. The samples of dried food were professionally packed in a factory and packaged dried apricots were exposed to C. lactis and dog food to T. putrescentiae. After 3 months of exposure, the infestation and mite density of the prepackaged food was assessed. Mites were found to infest six types of packages. Of the packaging types with mites, 1-5 samples were infested and the maximum abundance was 1,900 mites g(-1) of dried food. Mites entered the prepackaged food by faulty sealing. Inadequate sealing is suggested to be the major cause of the emerged infestation of dried food.

Equine intradermal test threshold concentrations for house dust mite and storage mite allergens and identification of stable acari fauna

BACKGROUND

House dust mite (HDM) and storage mite (SM) stable fauna and their associated equine intradermal test (IDT) threshold concentrations (TCs) for the midwestern region of the USA are unknown.

HYPOTHESIS/OBJECTIVES

To determine IDT TCs and serum IgE concentrations for two HDM and three SM species in clinically normal horses over two seasons, and to identify the mite taxa and habitats in a stable.

ANIMALS

Thirty-eight clinically normal horses.

METHODS

Threshold concentrations for HDMs and SMs were determined using IDT subjective measurements and a statistical model. An enzyme-linked immunosorbent assay was used to quantify serum IgE concentrations for the same mite species. A modified flotation method was used to identify morphologically HDMs and SMs.

RESULTS

Subjective IDT TCs were as follows: 1:80,000 w/v for Dermatophagoides farinae in both seasons; 1:80,000 w/v in spring and 1:160,000 w/v in late summer for Dermatophagoides pteronyssinus; 1:40,000 w/v in spring and 1:20,000 w/v in late summer for Acarus siro; 1:20,000 w/v for Lepidoglyphus destructor in both seasons; and 1:20,000 w/v in spring and 1:10,000 w/v in late summer for Tyrophagus putrescentiae. Statistically significant associations for increased serum IgE and a positive IDT reaction were evident for D. farinae in the spring and D. pteronyssinus in both seasons. One mite from all four genera specific to this study was identified; however,two HDM and A. siro species were not detected.Conclusions and clinical importance – This study established HDM and SM IDT dilution concentrations for the horses in this region. Exposure to diverse acaridae fauna may contribute to the pathogenesis of equine allergic disease.

The genomics revolution: will canine atopic dermatitis be predictable and preventable?

BACKGROUND

Heritability studies suggest that atopic dermatitis (AD) involves multiple genes and interactions with environmental factors. Advances in genomics have given us powerful techniques to study the genetics of AD.

OBJECTIVE

To review the application of these techniques to canine AD.

RESULTS

Candidate genes can be studied using quantitative PCR and genomic techniques, but these are hypothesis-dependent techniques and may miss novel genes. Hypothesis-free techniques avoid this limitation. Microarrays quantify expression of large numbers of genes, although false-positive associations are common. In the future, expression profiling could be used to produce a complete tissue transcriptome. Genome-wide linkage studies can detect AD-associated loci if enough affected dogs and unaffected relatives are recruited. Genome-wide association studies can be used to discover AD-associated single nucleotide polymorphisms without relying on related dogs. Genomic studies in dogs have implicated numerous genes in the pathogenesis of AD, including those involved in innate and adaptive immunity, inflammation, cell cycle, apoptosis, skin barrier formation and transcription regulation. These findings, however, have been inconsistent, and problems include low case numbers, inappropriate controls, inconsistent diagnosis, incomplete genome coverage, low-penetrance mutations and environmental factors.

CONCLUSIONS

Canine AD has a complex genotype that varies between breeds and gene pools. Breeding programmes to eliminate AD are therefore unlikely to succeed, but this complexity could explain variations in clinical phenotype and response to treatment. Genotyping of affected dogs will identify novel target molecules and enable better targeting of treatment and management options. However, we must avoid misuse of genomic data.