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A patient is presented herein with an acute generalized eczematoid eruption. The onset occurred in late spring and was caused by the American bird mite, Dermanyssus americanus. A review of mite infestations is presented. We suggest that puzzling cutaneous eruptions be evaluated closely as being possibly caused by mites.
The synthetic glucocorticoid dexamethasone was used to suppress bovine T-lymphocyte function. Dexamethasone-treated animals were challenged with Psoroptes ovis (Hering) to determine if the immunosuppressive treatment would normalize susceptibility to infestation. Dexamethasone suppressed T-lymphocyte function and anti-P. ovis antibody production, and delayed the onset of scab lesions. All animals were not equally susceptible to infestation as a result of dexamethasone treatment. These data further support the importance of anti-P. ovis antibody in colonization of cattle by P. ovis and the pathology associated with scab mite infestation.
Parasitic mites cause a variety of dermatoses in domestic animals. The clinical signs, diagnosis, and treatment of canine and feline demodicosis, canine scabies, notoedric mange, cheyletiellosis, otodectic mange, and other mite infestations are discussed.
Three studies were conducted to evaluate the therapeutic and protective efficacy of doramectin when given by injection at a dose of 200 micrograms/kg against induced Psoroptes otis infestations of cattle. The first study investigated therapeutic efficacy. Mite infestations were established on 15 test animals held in stanchions by transfer of material from infested donor calves. Test animals were then allotted on the basis of mite counts to a treatment group (10 animals) which received doramectin and a control group (5 animals) which received saline. Skin scrapings were collected for mite counts on the day before treatment and on days 7, 14, 21 and 28 after treatment. Efficacy assessed on the basis of the proportion of animals cured by day 28 was 100%. The second study was designed to determine the duration of protective efficacy. Forty-eight scabies-free heifers were allotted to a treated group of 32 which received doramectin, and a control group of 16 which remained untreated. These treatment groups were each divided into eight subgroups. Commencing on treatment day and continuing at weekly intervals for 7 weeks, a subgroup of animals from each treatment was placed in stanchions and challenged by transfer of material from infested donor calves. Skin scrapings for mite counts were collected 7 and 14 days later. Infestations were successfully established on all untreated control calves. Doramectin prevented the establishment of infestation for three weeks and significantly (P < 0.05) reduced infestation levels for an additional two weeks. The third study established the duration of residual protection conferred by doramectin and ivermectin under contact transmission. Ninety-six scabies-free heifers were divided into two equal treatment groups. Animals in one group received doramectin and animals in the other group received ivermectin at its recommended dose of 200 micrograms/kg by subcutaneous injection. Each treatment group was then divided into eight subgroups of six animals. Commencing on treatment day and continuing at weekly intervals for 7 weeks a subgroup of animals from each treatment was exposed to purposely infested seeder animals for one week. Three animals from each treatment subgroup were then placed in individual stanchions in which grooming was prevented and the other three were placed together in a pen where normal grooming behavior was permitted. Skin scrapings for mite counts were collected at weekly intervals for up to 4 weeks. Doramectin provided complete protection against infestation for five weeks compared to four weeks for ivermectin. These periods were not influenced by grooming behavior.
Theory suggests that the evolution of parasite virulence is linked to the dynamics of parasite transmission. All else being equal, parasites transmitted vertically from parents to offspring should be less virulent than parasites capable of horizontal transmission to unrelated hosts. This is because the fitness of vertically transmitted parasites is tightly linked to the reproductive success of the host, whereas the fitness of horizontally transmitted parasites is relatively independent of host reproduction. The virulence-transmission relation has seldom been tested because of difficulties inherent in comparing virulences of different parasite-host systems. We compared the virulence of lice and mites infesting a single group of captive rock doves (Columba livia). Lice, which were vertically transmitted, had no detectable effect on host fitness, whereas horizontally transmitted mites drove host reproductive success to zero. These results, in conjunction with a survey of the literature, support the hypothesis that ectoparasite virulence is linked to the mode of transmission.
The ectoparasitic mite, Varroa destructor, is the most destructive parasite of managed honeybee colonies worldwide. Since V. destructor transfers pathogens to honeybees, it may be adaptive for bees to respond to mite infestation by upregulating their immune responses. Mites, however, may overcome the host's immune responses by suppressing them, which could facilitate the mite's ability to feed on hemolymph. A humoral immune response of bees parasitized by V. destructor may be detected by studying the expression levels of antibacterial peptides, such as abaecin and defensin, known to be immune-responsive. Expression levels for these two antibacterial peptides changed non-linearly with respect to the number of mites parasitizing honeybee pupae. Bees exposed to low or moderate number of mites had fewer immune-related transcripts than pupae that were never parasitized or pupae with high mite loads. Although many of the pupae tested indicated the presence of bacteria, no correlation with mite numbers or immune-response levels existed. All bees tested negative for acute paralysis and Kashmir bee viruses known to be vectored by V. destructor.
Folliculitis is a common complaint and its etiology may be related to a variety of factors. We examine a case involving a 57-year-old white man presenting with scalp erythema and folliculitis secondary to Demodex mite infestation. We discuss the pathophysiology of Demodex folliculitis, as well as the epidemiology, clinical manifestation, diagnosis, and treatment of this infection.
This experiment assessed the efficacy of rotenone and oxalic acid (OA) in an aqueous sugar solution in controlling the honeybee mite Varroa destructor. Colonies were populated with mite-infested brood combs and worker bees. Three rotenone or OA treatments administered during the period with capped brood on 31 July, 14 and 18 August resulted in an average efficacy of 24.10%. In untreated colonies mite mortality averaged 5.40%. No significant differences (P>0.05) were found between the rotenone and OA treatments. Three OA treatments administered on 9, 12 and 18 September resulted in a 77.93% mite mortality. An increase in mite drop (P<0.05) was observed at 2 and 4 days after each treatment. OA applications in broodless colonies resulted in significantly (P<0.001) higher mite mortality rates (98.65% average) than the three treatments of rotenone or OA in colonies with capped brood. The dynamics of mite mortality after each rotenone or OA treatment are discussed in this study.
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A new compound containing imidacloprid 10% (w/v) and moxidectin 2.5% (w/v) (Advantage multi, Advocate) was applied as a spot-on treatment to mice experimentally infected with Trichuris muris. Case reports of reptiles found positive for nematode and mite infections following parasitological examination and treated with this compound are also discussed. The results demonstrated that the registered, recommended 2.5% moxidectin concentration for use in dogs was sufficient to eliminate nematodes and mites in reptiles. Infections with nematodes were successfully treated with a single application. Mite infestations in reptiles were eliminated using a treatment repeated on 3 consecutive days.
Aeration is a promising alternative to the use of pesticides for the control of storage insects by cooling bulk grain, but its effectiveness against mite pests is neither fully understood nor optimised. For this reason, the productivity of three species of storage mites, Acarus siro, Lepidoglyphus destructor and Tyrophagus longior, was studied in a laboratory-based experiment at four combinations of temperature and humidity (10 degrees C and 70% RH, 10 degrees C and 80% RH, 20 degrees C and 70% RH, 20 degrees C and 80% RH) with and without an airflow (at 10 m3/h/tonne, equalling 2.5 1/s/tonne, in tubes containing 15 g of grain). This is the first time that a study has examined the three principal components of aeration separately from each other. The effect of these factors was different for each species. For A. siro, temperature was the most important factor, while airflow and humidity were of similar but lesser importance. For T. longior, temperature was more important than humidity, while the reverse was true for L. destructor. For these two species, airflow was the least important factor. The airflow decreased the productivity of L. destructor and T. longior but increased the productivity of A. siro. This increase in productivity confirms that, in practice, prevention of mite infestations, in particular A. siro, will require storage of grain at low temperature, relative humidity and moisture content.
The deformations of bees occurring in connection with varroatosis was examined both in case of natural and artificial infestation. Under both conditions, the number of bees showing wing deformations increased with the degree of mite infestation. Shortened abdomina, however, only appeared in the case of natural infestation. Inadequate brood care in colonies severely infested by Varroa mites is supposed to be responsible. Wing deformations could be produced by experimental haemolymph extraction.
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During the summers of 1982 and 1983, black-tailed prairie dogs (Cynomys ludovicianus) were examined for parasites. Those collected and their respective prevalence included Linognathoides cynomyis (46.3%), Opisocrostis hirsutus (53.7%), Opisocrostis tuberculatus cynomuris (2.4%), Androlaelaps fahrenholzi (12.2%), Ixodes sculptus (2.4%) and Dermacentor andersoni (4.9%). The collection data indicated that L. cynomyis, O. hirsutus and A. fahrenholzi were at low population densities during this period.
Thoracic radiographs of rhesus macaques should be performed with short exposure times (1/60 s or faster) and the patient in the erect position. The patient's neck should be extended dorsally, and the arms extended above and behind the head. The tracheobronchial and lobar pulmonary anatomic features of the rhesus macaque are similar to those of the dog. The pulmonary parenchymal pattern also is similar; however, the interstitial markings are somewhat more prominent in the macaque. This may be due to lung mite infestation. The macaque does not appear from a radiologic standpoint to be superior as an animal model to dogs or cats unless there is something specific about the response or susceptibility to a disease being studied.
A 4-month-old female kitten developed generalized ataxia, mild tremors, weakness, incoordination, and miosis after receiving an injection of ivermectin (0.3 mg/kg of body weight, SC) for treatment of ear mite infestation. The kitten became comatose within 12 hours, and despite supportive treatment, died 7 days after administration of ivermectin. Caution should be exercised when this drug is administered parenterally to kittens.
Ivermectin was used for treating a breeding colony of guinea pigs heavily infested with fur mite Chirodiscoides caviae. In preliminary experiments on different dosages and routes of administration, spraying with diluted Ivomec (ivermectin 0.2 mg/ml) as well as applying undiluted ivermectin (10 mg/ml) drops on the fur proved effective and practical. The breeding colony was treated with diluted ivermectin aerosol and retreated two weeks later with undiluted ivermectin drops applied to the coat. After 3 months neither mites nor mite eggs were observed on microscopic examination. Two-and-a-half years later, the guinea pigs are still free of mites.
Spinosad is a reduced-risk insecticide derived as a fermentation product from the soil actinomycete Saccharopolyspora spinosa. It is toxic by ingestion and contact and has a unique mode of action on the insect nervous system. Spinosad exhibits a high degree of selective toxicity towards the insect orders Lepidoptera, Diptera and Thysanoptera, but is less toxic to many beneficial arthropods. To determine if spinosad could be valuable as an alternative acaricide for the control of Tetranychus urticae, laboratory toxicity experiments with leaf-disk bio-assays were performed on a laboratory susceptible and several resistant strains. LC50 values were rather high in comparison with newly developed commercial acaricides. Surprisingly, when spinosad was applied to the roots of tomato plants in rock wool, excellent control of spider mites was obtained. Apparently, spinosad has systemic properties and quantities as low as 1 mg/plant could protect tomato plants from mite infestation. Different substrates with varying percentage of clay and organic matter were tested in comparison with rockwool and showed that sufficient control was restricted to the rockwool substrate. Consequently, a dose-response experiment with tomato plants grown in rockwool was set up. The persistence of spinosad toxicity when applied via the roots was determined, and pointed to a long lasting control (up to 30 DAT). Spinosad amounts in leaves after systemic application were determined with an immunological technique to quantify spinosad uptake. Correlations between mite control, spinosad uptake and leaf concentrations can be helpful to determine the necessary dose in field situations.