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Molecular cloning of Blomia tropicalis allergens--a major source of dust mite allergens in the tropics and subtropics.

Allergic asthma, rhinitis, rhinoconjunctivitis and atopic dermatitis are the most common allergic disorders that are caused by the house dust mite (HDM). Beside pyroglyphid mites, the clinical importance of non-pyroglyphid mites has also been increasingly recognized in the recent years. Blomia tropicalis is the most important and ubiquitous mite species in tropical and subtropical regions of the world. Well-standardized and characterized allergens are essential for the diagnosis and therapy of house dust mite allergy as well as for the study of the pathophysiology of allergic disease. With the introduction of molecular biology, a number of house dust mite allergens were obtained by cloning the genes encoding the allergens. To date, seven allergens from Blomia tropicalis have been identified and characterized. Among these, Blo t 5, with unknown function, is the major allergen of Blomia tropicalis, with up to 92% of allergic patients sensitized to it. Native Blo t 5 has been purified and shown to consist of multiple isoforms. With advancing knowledge of these specific allergens, it is anticipated that targeted, effective, diagnostic, efficacious and safe therapeutic modalities would be developed.

Allergens↗

House dust mite fauna in western Anatolia, Turkey.

House dust mites play an important role in the pathogenesis of allergic diseases. Many factors may influence mite growth. The presence of mites is related to mean temperature and humidity as well as altitude. The aim of this study was to analyze the mite fauna in 5 regions of western Anatolia, Turkey, that have similar climatic properties with low mean temperature and humidity, but differ in altitude. During the period October-November 2004, house dust was collected from 290 homes in 5 different cities. House dust mites were isolated in 67 (23.1%) of 290 samples. The family Pyroglyphidae (Astigmata) was present in all positive samples. This study suggests that the selected western Anatolian regions that share similar environmental conditions host similar dust mite populations.

Animals↗

House dust mite sensitivity is a factor in chronic urticaria.

BACKGROUND: Chronic urticaria is one of the perplexing problems faced by clinicians. There are a few reports associating house dust mite sensitivity with chronic urticaria, based upon the patient's history as well as intradermal skin testing and in vitro analysis. AIMS: To investigate the possible association between house dust mite sensitivity and chronic urticaria. METHODS: In this case control study three groups of patients were enrolled. Group I: Chronic urticaria (73 subjects). Group II: Chronic urticaria with collateral allergic disorders (49 subjects). Group III: Normal subjects without chronic urticaria or other allergies (25 subjects). All the patients underwent skin prick testing with antigens of the house dust mite, Dermatophagoides pteronyssinus (DP) and Dermatophagoides farinae (DF), with positive and negative controls. RESULTS: Among the patients with chronic urticaria, 78/122 (64%) patients had skin sensitivity to house dust mites. Out of these, 39/73 (53%) had chronic urticaria alone and 39/49 (79%) had chronic urticaria with other associated allergies. Among the normal control subjects, 7/25(28%) reacted positively to house dust mites. CONCLUSION: This study suggests a possible association of house dust mite sensitivity with chronic urticaria.

Adult↗

First report on sensitization to allergens of a house dust mite, Suidasia pontifica (Acari: Saproglyphidae).

A species of house dust mite, Suidasia pontifica, was recently shown to produce allergens affecting man. The species may be as important as other allergen producing mite in sensitization and causing allergic symptoms in Malaysians. Surveys conducted demonstrated that 80% of the houses surveyed were positive for this mite with densities ranged from 2 to 50 mites per gram of dust. Colonies of the species has been successfully established and materials from those colonies have been used to produce extracts for studies on sensitization to the mites. A total of 85 suspected allergic rhinitis patients were tested and 74.1% demonstrated positive reactions. Extract of this mite should be considered for routine diagnostic testing and possible immunotherapy.

Acari↗

Mite allergen exposure, sensitisation and clinical symptoms in Valdivia, Chile.

One hundred consecutive asthmatic paediatric patients were evaluated and skin tested with a battery of skin prick test reagents, including 8 different standardized house dust mite extracts. Asthma severity was graded according to the Global Initiative for Asthma (GINA) document in mild persistent (52 patients), moderate persistent (39) and severe persistent (9). Sixty patients had asthma and allergic rhinitis, 12 asthma and eczema, and 8 asthma, allergic rhinitis and eczema. The patient population was divided into 2 different socioeconomic groups (50 patients per group) based on a standardized, validated questionnaire. A dust sample was collected with an adapted vacuum cleaner from the mattress of each patient and analysed for Der p 1, Der f 1 and Der p 2 allergen content using monoclonal antibodies. Eighty patients were skin test positive to at least one mite species. All positive skin test patients were positive to Dermatophagoides pteronyssinus, 99% to D. farinae, 92% to Euroglyphus maynei, 80% to Lepidoglyphus destructor, 73% to Tyrophagus putrescientae, 72% to Blomia tropicalis; 70% to Acarus siro and 68% to Chortoglyphus arcuatus. All patients with severe persistent asthma had a positive skin test to mites, 85% in the moderate group, and 73% in the mild group (p < 0.01). 95% of patients with asthma and allergic rhinitis had a positive skin test to mites, 92% of patients with asthma and eczema and 100% of patients with asthma, allergic rhinitis and eczema; (p < 0.01). Mean Der p 1, Der f 1 and Der p 2 allergen concentrations were 18.3, 0.6 and 5.6 microg/g of mattress dust, respectively. Mean Der p 1 allergen levels in the middle-low socioeconomic group were significantly higher than in the middle high group (p < 0.01). There is a high rate of allergic sensitisation among pediatric asthmatic patients in Chile. More than one species are implicated, although sensitisation and exposure to D. pteronyssinus predominates. Mite allergic patients are exposed to high mite allergen concentrations, exceeding previously established risk levels for sensitisation and symptoms.

Adolescent↗

CACTA and MITE transposon distributions on a genetic map of rice using F15 RILs derived from Milyang 23 and Gihobyeo hybrids.

Up to 35% of the rice genome consists of various kinds of transposons, and CACTA and MITE are two of the major class 2 DNA transposons in the genome. We have employed the consensus sequences of Rim2/Hipa CACTA, Stowaway MITE Pangrangja, and Tourist MITE Ditto for transposon display (TD) analysis to locate them on a genetic map, with 58 SSR markers used to anchor them. The TD analysis produced a high profile of the polymorphisms between the parental lines, Oryza sativa var. Gihobyeo/O. sativa var. Milyang, in intraspecific F15 RIL lines, locating 368 markers of Rim2/Hipa CACTA, 78 markers of Tourist MITE Ditto, and 22 markers of Stowaway MITE Pangrangja. In the segregation analysis, non-parental segregating bands and segregation distortion bands were observed. The recombinant genetic map spans 3023.9 cM, with 5.7 cM the average distance between markers. The TD markers were distributed unequally on the chromosomes because many TD markers were located in pericentric chromosomal regions except in the cases of chromosomes 2, 3, 6 and 9. Although the number of transposon markers was not sufficient to include all rice class 2 transposons, the current map of CACTA and MITE transposons should provide new insight into the genome organization of rice since no previous DNA transposon map is available.

Chromosome Mapping↗

A technique for quantitative evaluation of ectoparasitic mites and insects of domestic animals.

A modified KOH dissolution technique using Tween 80 has been developed for the diagnosis and quantitative evaluation of ectoparasitic mites and insects of veterinary importance. Fifty intact skin segments from ten different domestic animals were artificially inoculated in vitro with ten specimens each of the mites Sarcoptes scabiei, Chorioptes bovis, Psoroptes ovis and Demodex caprae and insects Haematopinus eurysternus and Bovicola bovis. Sixty-seven to 88% of the mites and 80-99% of the insects were recovered by this technique. Using this method, parasitic mites and insects were found and identified in all skin scrapings from ten naturally infested animals. Using Cook's dissolution technique in our experimental design, 63.4% of C. bovis and 65% of S. scabiei mites were recovered.

Animals↗

Factors affecting the prevalence of mange-mite infestations in stray dogs of Yucatán, Mexico.

The aim of the present study was to determine the factors affecting the prevalence of mange-mite infestations in stray dogs of Yucatán, Mexico. The study was carried out in 200 stray dogs of Mérida capital city of Yucatán, Mexico. Four samples (head, thoracic-abdominal area, extremities and ear) were taken from each animal by skin scraping and examined microscopically in 10% KOH solution to detect the presence of mites. Mites were also collected from the external ear canal of dogs using cotton-tipped swabs. The prevalence of different mite species was calculated. A primary screening was performed using 2xK contingency tables of exposure variables. All variables with P< or =0.20 were analyzed by a logistic-binomial regression. The overall prevalence was 34%. Demodex canis (23.0%) was the most frequent mite, followed by Sarcoptes scabei var. canis (7.0%) and Otodectes cynotis (3.5%). The following factors were found: body condition (bad, OR: 5.35, CI 95%: 1.66-17.3; regular, OR: 3.72, CI 95%: 1.39-9.99) and the presence of macroscopic lesions of dermatosis (OR: 42.80, CI 95%: 13.65-134.24).

Age Factors↗

Comparative effects of mites and lice on the reproductive success of rock doves (Columba livia).

We report experimental data comparing the effects of Mesostigmatid mites and Ischnoceran lice on the reproductive performance of a single group of captive rock doves (Columba livia). Several components of host reproductive success were compared for the two groups, including number of eggs laid, hatching success, nestling growth rates, fledging success, post-fledging body mass and survival. Adult body mass and survival were also compared. There was a dramatic difference in the effects of the mites and lice. The former drove host reproductive success to zero, mainly by agitating adults and causing them to incubate eggs less faithfully. Nestling growth rates and post-fledging survival were also significantly reduced by mites. Lice showed no effect on reproductive success whatsoever, even though the feather damage they cause is known to have energetic consequences (Booth, Clayton & Block, 1993). Neither parasite had a significant effect on adult birds. Although Ischnocera are found on most species of birds, our results for lice constitute the first experimental test of the impact of Ischnocera on avian reproductive success (preliminary report by Clayton & Tompkins, 1994). We discuss reasons for the different effects of mites and lice, including the relationship of horizontal (mites) and vertical (lice) transmission to the evolution of virulence.

Animals↗

An epidemiological survey of therapy and diagnostic procedures used by Norwegian small animal practitioners in cases of nasal mite (Pneumonyssoides caninum) infection in dogs.

Forty per cent of the members of the Norwegian Small Animal Veterinary Association (NSAVA) returned a questionnaire regarding the treatment and diagnosis of canine nasal mite infection in their practices in 1996. A total of 2392 dogs were treated for this infection by 156 NSAVA members in clinical practice in that year, averaging 15.3 treated dogs per veterinarian. An estimated minimum of 6000 Norwegian dogs were treated for nasal mite infection in 1996, at an estimated cost of treatment exceeding 3.3 million NOK. Fifty-nine per cent of the practitioners included at least a case history and clinical examination as diagnostic criteria prior to initiating treatment for nasal mite infection. Fewer than 10% routinely performed more thorough diagnostic procedures, and only 1.8% of the diagnoses were verified prior to treatment. A total of 27 different treatment regimens, involving either subcutaneously injected ivermectin or orally administered milbemycin oxime, were routinely used by NSAVA veterinarians to treat these dogs. Seventy-two (53%) of the veterinarians used ivermectin exclusively, 14 (10%) used milbemycin oxime exclusively, while 50 (37%) used both ivermectin and milbemycin oxime. No other drugs were used. Evaluation of treatment was made by assessing resolution of the clinical signs following treatment, and 97% of the veterinarians were satisfied with the effect of the treatment regimen they used. Adverse side-effects following treatment for nasal mite infection in 1996 were seen on 9 occasions; 4 following ivermectin administration and 2 following milbemycin oxime treatment, while in 3 cases no information on the drug used was provided. The risk of adverse reactions to treatment of nasal mite infection in dogs was 0.4%.

Animals↗

Influence of volunteer wheat plant condition on movement of the wheat curl mite, Aceria tosichella, in winter wheat.

The wheat curl mite (WCM), Aceria tosichella Keifer, is the vector of wheat streak mosaic virus and high plains virus which cause significant crop loss in winter wheat throughout the western Great Plains. Volunteer wheat emerging before harvest, as a result of severe hail, is the primary source of mites and virus that infect fall-planted winter wheat. Wind-borne movement of the WCM is of key importance in the spread and infection of the virus complex. Significant movement of WCM from wheat has been thought to be closely tied to the senescence or deterioration of the host. Results from field and greenhouse studies indicated that movement from un-vernalized winter wheat was not closely associated with the deterioration of the wheat host. Greenhouse studies showed no correlation between WCM movement and plant condition, but there was a highly significant relationship between WCM movement and mite population on the host plant. Field studies did not demonstrate increased movement associated with deteriorating un-vernalized winter wheat. However, healthier hosts which were able to support a larger population of mites were associated with increased movement. The main influence on the level of mite movement relates to the size of the source population and not the condition of the host plant, but plant condition appears to be a factor in limiting the increase of the WCM population.

Animals↗

Phytoseiid mites on unsprayed apple trees in Oregon, and other western states (USA): distributions, life-style types and relevance to commercial orchards.

In unsprayed apple trees in eastern Oregon, Galendromus flumenis (Chant), Galendromus occidentalis (Nesbitt), Typhlodromus caudiglans Schuster and Metaseiulus citri (Garman and McGregor) were common phytoseiid mites; common plant-feeding mites were the eriophyid, Aculus schlechtendali Nalepa, the brown mite, Bryobia rubrioculus (Scheuten) and Eotetranychus spp.; apple rust mites seemed to be the primary prey for phytoseiids; the spider mites, Tetranychus urticae Koch and Panonychus ulmi (Koch) were scarce except for a few local outbreaks; the stigmaeid Zetzellia mali (Ewing) was at 10% of sites and its densities were inversely related to phytoseiid densities; phytoseiids were absent at some sites, particularly at high elevations where winters are severe. In seven Oregon ecoregions, G. flumenis was often at lower elevations in valleys with moderate winters; T. caudiglans was often at higher elevations; G. occidentalis was often at intermediate elevations, in young trees, and near where pesticides were used; it dominated in unsprayed trees only in almost treeless, sage-covered areas; M. citri was usually in older apple trees near agriculture. In mixed phytoseiid populations, M. citri, a generalist, and G. occidentalis, a specialist, occurred more often than expected; G. occidentalis was mostly found with T. caudiglans, a generalist; G. flumenis, a generalist, occurred less with others, possibly because it competes with both specialists and generalists. Analyses of species' distributions with multiple regression and genetic models gave explanatory r2s of 0.019-0.318. Of 29 variables, altitude of site, intensity of agricultural management, tree age, plant types, and Z. mali levels helped explain phytoseiid species presence. In the western USA, G. flumenis dominated in middle-southern latitudes; T. caudiglans dominated in the north near the Canadian border; G. occidentalis dominated in middle latitudes in parts of Washington, Idaho, Montana, and Wyoming; M. citri was at a few sites in these four states. Distributional and independent variable data were used to predict species presence at sites in Oregon with a 70% success rate. We discuss phytoseiid life-style types, community dynamics, presence in organic/conventional orchards, and trends as more selective IPM methods are used in apple orchards.

Animals↗

The poultry red mite, Dermanyssus gallinae, a potential vector of Erysipelothrix rhusiopathiae causing erysipelas in hens.

Erysipelas is a bacterial disease caused by Erysipelothrix rhusiopathiae, which may infect swine as well as several other species of mammals and birds, including domestic fowl. In poultry, erysipelas may cause sudden high mortality due to septicemia. This communication describes the first isolation of E. rhusiopathiae from the haematophagous poultry red mite, Dermanyssus gallinae DeGeer (Acari: Dermanyssidae), that was collected on three farms where hen erysipelas was diagnosed. The bacteria were isolated from the integument as well as from the interior of the mites. Serotypes 1a and 1b of E. rhusiopathiae found in the mites corresponded with those isolated from the diseased birds. These findings imply that D. gallinae is a potential vector of E. rhusiopathiae. The current lack of effective measures to control D. gallinae causes recurring mite problems in poultry facilities once afflicted by this parasite. Consequently, mites containing E. rhusiopathiae may act as reservoir hosts of this bacterium, allowing it to persist in the poultry house between flock cycles as a source of infection for the replacement pullets. The zoonotic potentials of both E. rhusiopathiae and D. gallinae should also be considered.

Animals↗

Presence of Borrelia burgdorferi sensu lato in mites parasitizing small rodents.

Ticks (especially those in the family Ixodidae) are the primary vectors of the infectious agent Borrelia burgdorferi sensu lato, which causes Lyme disease. To determine the potential role of mites as vectors of B. burgdorferi sensu lato, mites were collected from wild rodents in the Bazantula region of North Moravia (Czech Republic). These samples were examined for the presence of Borreliae by using DFM and PCR methods. Mites positive for the presence of DNA of B. burgdorferi sensu lato were determined as members of the families Haemogamasidae and Parasitidae. One sample from a mite of genus Haemogamasus was successfully isolated, and the specimen was confirmed as B. afzelii by using PCR-RFLP and by gradient SDS-PAGE. This suggests the possible participation of gamasid mites in borrelial circulation in nature and also points to the utility of further such studies to identify potential vectors (other than ticks) of the spirochete.

Animals↗

Use of selamectin for the treatment of psoroptic and sarcoptic mite infestation in rabbits.

Selamectin, a novel avermectin compound, was evaluated for its efficacy against naturally occurring infestations of Psoroptes cuniculi and Sarcoptes scabiei. A total of 42 New Zealand rabbits with psoroptic mange and 37 Angora rabbits with sarcoptic mange were used in the present study. On day 0, infested rabbits were treated topically with either selamectin at minimum dose of 6 mg kg(-1) (6-18 mg kg(-1) for New Zealand rabbits, n = 31 and 10-12 mg kg(-1) for Angora rabbits, n = 23) or vehicle only (control groups, n = 11 for New Zealand rabbits, n = 14 for Angora rabbits). The efficacy of selamectin was assessed both clinically and parasitologically by the presence or absence of viable mites. Rabbits were scraped for sarcoptic mites on days 7, 14, 28, 42 and 56 and had otoscopeic and/or microscopic examination for the detection of Psoroptes mites on days 7, 14, 42 and 56. Fisher's exact test was used to assess differences between the vehicle and selamectin treatment in the number of rabbits without mites (cure rates) on each assessment date. It was found that significantly fewer selamectin-treated rabbits had mites detected on skin scrapings (for S. scabiei) or otoscopeic and/or microscopic examination (for P. cuniculi) (P < 0.01) than the vehicle group. Results of the present study suggest that selamectin is effective against naturally infestations of P. cuniculi and S. scabiei in rabbits.

Administration, Cutaneous↗

Short form of Demodex species mite in the dog: occurrence and measurements.

A form of Demodex species mite shorter in length than Demodex canis was found in six consecutive cases of canine demodicosis. The mean length of the parasite was 122.6 microns (SD 12.0 microns, 39 mites counted), significantly shorter than either male or female forms of D canis (P < 0.0001). The proportion of short to long mites in each case varied from 0.5 to 22 per 100. In young dogs, skin signs associated with the presence of mites were first noted after about seven months, while in the oldest subject the disease became apparent at 10 years of age. This form of mite has now been found in four countries over three continents, the findings suggesting that it is not uncommon and is acquired in puppyhood, although it may be carried unnoticed for many years.

Animals↗

Ecology and host specificity of laelapine mites (Acari: Laelapidae) of small mammals in an Atlantic forest area of Brazil.

Mesostigmatic mites of the Laelapinae Berlese, 1892 (Acari: Laelapidae) are nidicolous arthropods that commonly occur in the fur of Neotropical small mammmals. In this 2-yr study, the laelapine acarofauna associated with the small mammal community in an area of Atlantic forest on Ilha Grande, Rio de Janeiro State, was examined, including observations on patterns of host specificity, mite dispersal, ecology, and food habits. A total of 1,347 laelapines was sampled from the pelage of 6 species of small mammals (Marmosops incanus, Nectomys squamipes, Oryzomys russatus, Rhipidomys n. sp., Oxymycterus dasytrichus, and Trinomys dimidiatus), all of which occurred exclusively in monoxenous associations with their hosts. No evidence of a blood meal was observed in the gut of the mites. With the exception of the 2 species of Tur, mite populations on hosts were entirely or nearly restricted to adult females. These results, together with some morphological characteristics of laelapines, reinforce the hypotheses that Neotropical laelapine mites are not ectoparasitic, and that females disperse by phoresy.

Animals↗

Acquired immune response of white leghorn hens to populations of northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago).

Three levels (high, low and control) of northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago), were maintained on White Leghorn hens for 24 weeks. The hens were then treated with carbaryl to eradicate the mites, were induced to molt, and were reinfested with mites 9 weeks later. Subsequent levels of mites on the three groups showed that the degree of acquired immunity was related to the initial level of mite infestation.

Animals↗