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IgE and IgE antibody to mite in nasal fluid.

The levels of total IgE and IgE antibodies to mite per unit quantity of nasal fluid were successfully determined by our special method of collecting nasal fluid. The mean value of IgE was 80 +/- 101 U/ml, and that of IgE Ab 1.45 +/- 1.29/ml (RAST score) in NF. Nasal IgE concentration was approximately one twenthieth of serum IgE on the average, and nasal IgE Ab to mite was one half of serum IgE. The IgE Ab/IgE ratio was nine times greater in NF (0.0181) than in serum (0.0022). The concentration of IgE Ab to mite was very well correlated between serum and NF (correlation coefficient of 0.83), while that of IgE was not (coefficient of 0.51). IgE Ab to mite was also well correlated to IgE (coefficient of 0.78) in NF while it was not in serum (coefficient of 0.48). The correlation coefficient of nasal/serum IgA was 0.41; that of IgE/IgA in NF was 0.31; and that of IgE/total protein in NF was also 0.31. The possibility of local production and secretion of IgE Ab to specific allergen is discussed in detail.

Adolescent↗

The PCR-based detection of Leishmania major infections in Meriones libycus (Rodentia: Muridae) from southern Iran.

Cutaneous leishmaniasis (CL) is an increasing public-health problem in the countries of the Mediterranean region. In southern Iran, for example, the incidence of CL has more than doubled over the last decade. As part of an investigation of this worrying trend, the leishmanial infections of the wild rodents that may act as reservoir hosts were investigated in the Iranian province of Fars. Overall, 82 rodents, 56 of them Libyan jirds (Meriones libycus), were collected, in live traps, from a new, hypo-endemic focus of zoonotic CL. When Giemsa-stained smears of ear tissue or any lesions on the rodents were prepared and checked under a light microscope, amastigotes were found in the smears from six of the rodents, all M. libycus. None of the other rodents investigated was found to be infected. The infected rodents were encountered in two of the three areas studied. In PCR-based assays, the amastigotes seen in the ear smears and those from two recent human cases of CL from the focus were all found to be identical to a reference strain of L. major. It therefore seems that M. libycus is the main active reservoir host for ZCL in the focus.

Animals↗

Evaluation of Arkansas Rous sarcoma regressor and progressor lines and giant jungle fowl for genetic resistance to the northern fowl mite.

Arkansas B1B1R, B2B2R, and B3B3R regressor lines, Arkansas B1B1Pr, B2B2Pr, and B3B3Pr progressor lines, and Giant Jungle Fowl were infested simultaneously at 28 weeks of age with northern fowl mites. The chickens were maintained in similar environments and mite ratings were recorded weekly for 5 months. No strains were completely resistant to mites, but there were significant (P less than or equal to .05) differences among strains in degree of infestation. The regressor lines generally showed significantly (P less than or equal to .05) less infestation than the progressor lines for both female and male chickens. The regressor lines appear to have genetic factors from the Giant Jungle Fowl in the development of the regressor lines that imparted increased resistance to the northern fowl mite.

Animals↗

MITES (FAMILY TROMBICULIDAE) PARASITIZING BIRDS MIGRATING FROM AFRICA TO EUROPE.

The mechanisms of dissemination of arthropod-borne human and animal pathogens are of considerable interest to the epidemiologist, veterinarian and biologist. Birds which are hosts to such pathogens and their arthropod vectors could transport them over long distances during their spring and autumn migratory flights.In April 1961, birds migrating from Africa to Europe were collected in south-western Spain and examined for ectoparasites and antibodies to arboviruses. Fully engorged larvae of two species of trombiculid mites unknown in Europe (genera Neoschoengastia and Blankaartia) but found in Africa were collected from two of the migrating birds (redstart and little bittern), suggesting that the birds were carrying the mites from Africa to Europe.Trombiculid mites are the proven vectors of scrub typhus; they have also been implicated in the transmission of human haemorrhagic nephroso-nephritis. The finding of the mite larvae on migrating birds is therefore of some epidemiological interest and underlines the importance of obtaining more data on the dispersal of trombiculids by migrating birds.

Africa↗

A study on Demodex folliculorum mite density and immune response in patients with facial dermatoses.

In the present study, 40 patients with facial skin lesions and Demodex folliculorum (DF) mite density > 5/cm(2) by SSSB were evaluated for their immune response through counting T-cell subsets (CD3-CD4-CD8) and NK cells (CD16) numbers and IgG, M, D concentrations in peripheral blood in relation to DF mite density. They were 26 females and 14 males with overall mean age was 48.57+/-15.33 years. A control group of 40 healthy individuals without any skin diseases was enrolled. The mean DF mite density (MD) was 11.82+/-3.72/cm(2) in patients compared to 1.77+/-2.39 /cm(2) and a prevalence of 47.5% in controls. The difference was statistically significant. MD significantly correlated with age both in study and controls, but not with sex. A significant decrease in the absolute numbers of lymphocytes, T-cell subsets and NK cells was found in the study group in comparison with controls. Mean IgM level was significantly higher in patients. No significant correlation was observed between MD and the immune response. So, DF mites modulate the host cellular immune response to their advantage, as T-cell subsets and NK cells seem to be the target of immuno-suppression, favouring dermatosis development.

Adult↗

Multimodal approach to treatment for control of fur mites.

Ectoparasites pose numerous research, health, and management problems for researchers and institutions. Our facility management experience was complicated by recurrence of murine fur mite (Radfordia affinis) infestation after several rounds of single-mode fur mite treatment with dichlorvos in the cage bedding. Subsequently, we successfully eradicated the fur mites using a multidrug therapeutic protocol. Over an 8-wk treatment period, 2 applications of topical selamectin were administered in conjunction with amitraz- and fipronil-treated nestlets changed weekly. Mice tolerated the therapy well with no side effects noted, and to date there has been no recrudescence. To our knowledge, this report is the first to describe combined use of these specific therapeutic agents to control fur mite infestation in laboratory mice.

Animals↗

Ultrastructural and microprobe analysis of simian lung mite pigments.

Using light microscopy, polarizable amorphorous bodies with tinctorial characteristics of lipochromes and flocculent pigmental materials were found within the alveolar macrophages and peribronchiolar region of the lungs in a pig-tailed macaque (Macaca nemistrina) infected with simian lung mite (Pneumonyssus simicola). Examination of these pigmental bodies, using a high-voltage (1.2 meV) electron microscope and an energy-dispersive X-ray analysis system, indicated that the pigmental bodies contained a high concentration of silica. One female adult P simicola also was examined, and its digestive tract had visible, polarizable pigment and a high concentration of silica. Thus, lesions associated with lung mite infection in Old World monkeys may be superimposed by this silicotic condition, which may be associated with their arid, dusty, environment. Therefore, until the link between lung mite infection and silicosis is clarified, experimental inhalation toxicologic findings in mite-infected Old World monkeys should be interpreted cautiously.

Animals↗

Occupational dermatitis associated with straw itch mites (Pyemotes ventricosus).

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.

Adult↗

Antigens of the sheep scab mite Psoroptes ovis.

Sheep scab caused by the mite Psoroptes ovis (Hering) is a highly contagious disease of sheep. As a first step in developing a mite-derived vaccine for controlling the disease, the soluble antigens in mite extracts which induce an immune response in sheep were identified by electrophoretic and immunoblotting techniques. At least 22 proteins were present in P. ovis extracts as revealed by Coomassie Blue staining. Mite-infested sheep serum recognised six antigenic bands in the extracts with approximate relative molecular weights ranging from 12 to 183 kDa. A deeply staining band at 31.2 kDa and another at 41.8 kDa are of particular diagnostic value. Immunoblotting studies showed that there was no cross reactivity between P. ovis and two other ectoparasites of sheep in the UK, the sheep louse Bovicola ovis (Schrank) and the sheep tick Ixodes ricinus L.

Animals↗

Outbreak of tropical rat mite dermatitis in laboratory personnel.

An outbreak of tropical rate mite (Ornithonyssus bacoti) dermatitis occurred in a group of research and animal technicians. The technicians were affected with an intense pruritic dermatitis after exposure to asymptomatic laboratory mice infested with the mite. Locating the resident host of the mite is critical in the successful elimination of the mite from the premises and in preventing further contact with and irritation to human occupants.

Animals↗

Use of low-temperature field emission scanning electron microscopy to examine mites.

Partly because mites are microscopic in size and fragile in nature, acarologists estimate that less than five percent of extant species have been taxonomically described. Recently, data from conventional scanning electron microscopy (SEM) have been used to facilitate the descriptions and complement the information that has been historically obtained with the light microscope. However, the conventional preparation techniques associated with SEM frequently prevent or compromise the results. This study evaluated the use of low-temperature field emission SEM to image mites and their hosts. Results indicated that a modified cryofixation procedure, which was associated with this technique, retained the mites at their living/feeding sites in natural behavioral positions. Furthermore, the turgor of the specimens, even eggs and soft-bodied species, was also maintained. The structure and orientation of delicate structures such as setae, which would be subjected to mechanical damage during conventional chemical fixation, dehydration, and drying, were also preserved after cryofixation. Field emission SEM, which provided useful magnification beyond that attainable with a conventional SEM, also enabled resolution of ultrastructural features, such as tenent hairs on the empodium and pores on the dorsal surface that had not previously been observed. These advantages indicate that the low-temperature field emission SEM can provide important structural data that can be used to study the anatomy, morphology, and bioecology of mites.

Animals↗

Disease prevalence and transmission of Microsporidium phytoseiuli infecting the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae).

Isolated colonies of the predatory mite, Phytoseiulus persimilis, were used to gain information regarding prevalence and transmission of Microsporidium phytoseiuli. Two colonies of P. persimilis were reared on spider mite (Tetranychus urticae)-infested bean plants in isolated cages. Disease prevalence of predators from Colony 1 remained relatively low (between 0 and 15%) over 57 weeks of observation whereas disease prevalence of predators from Colony 2 increased over 3 months (from 12 to 100%). Disease prevalence among predators from Colony 1 had increased to 100% 2 months after weekly sampling had ceased for this colony and periodic sampling confirmed that disease prevalence among individuals of both colonies remained at 100%. Microsporidian spores were not detected in randomly chosen samples of T. urticae prey mites that were removed and examined biweekly during this period. Although numerous microsporidian spores were observed in smear preparations of fecal pellets examined by light microscopy, spores were not observed on leaf surfaces or predator feces when examined by SEM. The latter appeared as intact aggregates composed of numerous dumbbell-shaped crystals and it is unlikely that spores are liberated from intact fecal pellets onto leaf surfaces. Vertical transmission of M. phytoseiuli was 100%; horizontal transmission was low (14.3%) and occurred only when immature P. persimilis were permitted to develop in contact with infected immature and adult predators. The mean number of eggs produced per mated pair was highest when uninfected females were mated with uninfected males (63.2 eggs per mated pair). Although mean egg production decreased when one or both parents were infected, not all differences were significant. Male predatory mites did not contribute to infection of their progeny. Results suggest that routine examination of P. persimilis for microsporidian spores is essential for the management of M. phytoseiuli within P. persimilis colonies. Low disease prevalence and lack of obvious disease signs or symptoms, as in the case of M. phytoseiuli, increase the probability that these pathogens will escape notice unless individuals are routinely examined for pathogens.

Animals↗

Optimisation of a screening procedure for house dust mite numbers in carpets and preliminary application to buildings.

The relative performances of the mobility and heat escape methods for measuring house dust mite numbers in carpet has been evaluated. The optimum method was found to be the mobility method for 24 hours at ambient temperatures which exhibited a mite collection efficiency of approximately 30%. Measurements in three dwellings showed that the method should be applied to carpet at several locations in the living room and/or bedrooms as a general sampling procedure, or adjacent to loungeroom seating to determine the worst case scenario. Carpets using different types of fibre within the same dwelling should be assessed separately. For the limited number of dwellings investigated, wool carpets were found to exhibit higher mite numbers than nylon carpets, even when the former had been insect-resist treated. No house dust mites were found in the wool carpets of an office building which was mechanically ventilated and heated and achieved low indoor humidities in winter.

Animals↗

Wolbachia: intracellular manipulators of mite reproduction.

Cytoplasmically transmitted Wolbachia (alpha-Proteobacteria) are a group of closely related intracellular microorganisms that alter reproduction in arthropods. They are found in a few isopods and are widespread in insects. Wolbachia are implicated as the cause of parthenogenesis in parasitic wasps, feminization in isopods and reproductive (cytoplasmic) incompatibility in many insects. Here we report on the widespread occurrence of Wolbachia in spider mites and predatory mites based on a PCR assay for a 730 bp fragment of the ftsZ gene with primers that are specific for Wolbachia. An additional PCR, using two primer pairs that amplify a 259 bp region of the ftsZ gene that are diagnostic for the two Wolbachia subdivisions A and B, showed that infected mites only carried type B and not type A Wolbachia. The fact that some species tested negative for Wolbachia does not mean that the entire species is uninfected. We found that natural populations of Tetranychus urticae are polymorphic for the infection. The possible effects of Wolbachia on mite reproduction and post-zygotic reproductive isolation are discussed.

Animals↗

Effects of five insect growth regulators on laboratory populations of the North American house-dust mite, Dermatophagoides farinae.

The potential of insect growth regulators (methoprene, hydroprene, fenoxycarb, diflubenzuron and triflumuron) to control populations of the North American house-dust mite Dermatophagoides farinae (Hughes) was assessed in laboratory bioassays. Methoprene was most effective at suppressing population growth, especially at concentrations of 1.0% (10,000 ppm) and 5.0% (5000 ppm) active ingredient. Hydroprene, structurally related to methoprene, also suppressed house-dust mite populations but not as consistently as methoprene. Fenoxycarb may be effective at controlling house-dust mites but at greater concentrations than were tested. Diflubenzuron and triflumuron, two chitin-synthesis inhibitors, failed to suppress mite numbers and may, in fact, stimulate reproduction in some cases. Almost all concentration of the insect growth regulators were shown to be ineffective when assayed 90 days after treatment.

Animals↗

Water balance and humidity requirements of house dust mites.

The house dust mites, Dermatophagoides farinae, D. pteronyssinus and Euroglyphus maynei, are prevalent in homes in humid geographical areas throughout the world. These mites thrive in humid environments in human dwellings where there is no liquid water to drink. However, their bodies contain 70-75% water by weight, which must be maintained in order to reproduce. Their primary source of water is water vapor which is actively extracted from unsaturated air. At relative humidities above 65-70%, adequate amounts of water can be extracted from unsaturated air to compensate for that lost by all avenues. Active uptake is associated with ingestion of a hyperosmotic solution which is secreted by the supracoxal glands. Active mites do not survive longer than 6-11 days at RHs < or = 50%. They survive extended dry periods by forming a desiccation-resistant protonymphal stage which can survive for months at RHs below the critical humidity for active stages. Feeding rate and allergen production is directly influenced by RH. Mites feed, multiply, and produce more fecal matter at higher RHs than at lower ones.

Animals↗

How relevant are house dust mite-fungal interactions in laboratory culture to the natural dust system?

Both house dust and house dust mites Dermatophagoides pteronyssinus contained a wider range of fungi than laboratory mite cultures. In total, nine species of fungi were isolated from D. pteronyssinus in house dust, and these included three xerophilic species (Eurotium amstelodami, Aspergillus penicillioides and Wallemia sebi) commonly found in laboratory cultures of D. pteronyssinus. It is concluded that mites do interact with a similar range of fungi in natural dust and in laboratory culture, but that the diversity of fungal species in the laboratory is reduced and the density of individual fungal species in culture exceeds that of house dust. In a second experiment, dust samples were incubated at room temperature with 75% relative humidity. The diversity of fungi invariably declined from up to 13 genera to the few species recorded in laboratory culture. This suggests that the dominance of xerophilic fungi in laboratory mite rearings is mediated primarily by low relative humidity, and the exclusion of air-borne spores.

Air Microbiology↗

The colonisation of new houses by house dust mites (Acari: Pyroglyphidae).

House dust mites, Dermatophagoides species (Acari: Pyroglyphidae), produce allergens, known for the provocation of asthma and other allergic reactions. To determine the time needed for complete colonisation of a new house by house dust mites, dust samples were collected from carpets of houses varying from 2 weeks to 2 years in age. In contrast to the expectation, no relation was found between age of the houses on the one hand and average levels of mite-allergens Der pI and Der pII and mite numbers on the other. However, presence of dogs appeared to be positively related to allergen levels. Furthermore, carpets in bedrooms appeared to contain more allergens than carpets in living-rooms. Finally, the age of the mattress was not related to allergen levels of bedroom floors.

Allergens↗