Demodex sp.

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Demodex sp.
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<p align="CENTER"><span style="font-size: large;"><i><b>Demodex</b></i></span><span style="font-size: large;"><b> sp.</b></span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>ETYMOLOGY:</b></span><span style="font-size: medium;"><i>Demos</i></span><span style="font-size: medium;"> = tallow and </span><span style="font-size: medium;"><i>dex</i></span><span style="font-size: medium;"> = woodworm; this mite has not been assigned a specific name.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>SYNONYMS:</b></span><span style="font-size: medium;"> This mite has been recognized as separate from </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>cati</i></span><span style="font-size: medium;">, but no specific name has been given.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>HISTORY:</b></span><span style="font-size: medium;"> Conroy </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">. (1982) sent specimens of a </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"> recovered from a cat to Drs. Nutting and Desch for identification. They were informed that the speciments appeared distinct from Demodex cati and were similar in appearance to </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>criceti</i></span><span style="font-size: medium;"> which resides in the stratum corneum of the hamster. Chesney (1989) in his review of feline demodicosis summarized seven reports of feline infestations with this mite. Chesney also felt that the reports by Gabbert and Feldman (1976) and White and Ihrke (1983) probably dealt with this unnamed species based on the photographs of the mite that accompanied these case presentations. Chesney went on to discuss the report of Keep (1981) and stated that that these mites were also likely to be the unnamed species based on the description of the mites provided by Keep. Since the review of Chesney, additional cases of demodicosis due to this unnamed species have been reported, 3 cases by Guaguère (1993) and 3 cases by Morris (1996).</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>GEOGRAPHICAL DISTRIBUTION:</b></span><span style="font-size: medium;"> This unnamed species of mite has been reported from the United States (8 cases), from Europe (5 cases), and from Australia (one case). Chesney (1989) reports that the unnamed species occurred in the USA in a domestic longhaired cat (Trimmier, 1966); a Siamese cat (Gabbert and Feldman, 1979), a Siamese cat (Conroy </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">, 1982), a domestic shorthaired cat (Muller, 1983), a domestic shorthaired cat (McDougal and Novak, 1986), and in two domestic shorthaird cats (Medleau </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">., 1988). Morris (1996) describes infection in three Siamese cats in the United States. Chesney (1989) describes two cases from Europe: one from France in a domestic shorthaired cat (Carlotti </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">., 1986) and one from England in a domestic longhaired cat (Chesney, 1988). Guaguère (1993) has described three additional cases in domestic shorthaired cats in France. One Australian case is that of Wilkinson (1983) in a domestic shorthaired cat. Thus, of the 14 cases described, 5 have been described in Siamese cats, and all cases in Siamese cats have occurred in North America.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>LOCATION IN HOST:</b></span><span style="font-size: medium;"> The unnamed </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"> that occcurs is cats is found in the stratum corneum rather than in hair follicles. Two other species of </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"> that have been described from this location in their host include </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>criceti</i></span><span style="font-size: medium;"> of the hamster (Nutting and Rauch, 1958) and a species of </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"> which parasitizes </span><span style="font-size: medium;"><i>Onychomys</i></span><span style="font-size: medium;"><i>leucogaster, </i></span><span style="font-size: medium;">the grasshopper mouse (Nutting </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">., 1973). </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>IDENTIFICATION:</b></span><span style="font-size: medium;"> Chesney (1988) described two forms of the parasite, a longer form that measured about 143 to 148 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m in total lenght (gnathosoma 17 to 19 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m; podosoma 56 to 58 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m; and opisthosoma being 66 to 73 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m) with a maximum width of 37 to 41 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m. The shorter form was about 110 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m long and 28 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m wide (gnathosoma 16.5 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m, podosoma 47 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m, opisthosoma 47 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m). Foley (1995) gives measurements of 80 to 90 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m by 30 to 35 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">m. In the undamed </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"> of the cat, the opisthosoma makes up around 40% of the total body length, and in some of the illustrations it appears that significantly less than 40% of the total body length is made up of the opisthosoma. In </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>cati</i></span><span style="font-size: medium;">, the opisthosoma makes up about two-thirds of the total body length. There is no anus on any of the life cycle stages in the genus </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;">.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>LIFE CYCLE:</b></span><span style="font-size: medium;"> The location of the mite in the stratum corneum and the morphological resemblance to </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>criceti</i></span><span style="font-size: medium;"> has suggested that the biology is similar to that described for </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>criceti</i></span><span style="font-size: medium;">. Studies with </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>criceti</i></span><span style="font-size: medium;"> have indicated that this mite is transferred from mother to young during suckling. Very little else is known concerning this mite, and the different life-cycle stages have not been described in detail. It is assumed that the life cycle is similar to that described for </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>brevis</i></span><span style="font-size: medium;">. Thus, a six-legged larva hatches from the egg, develops to a six-legged protonymph, which matures to a nymph, which then matures to an adult male or female (Nutting, 1983). Work with </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>caprae</i></span><span style="font-size: medium;"> of the goat has revealed that only males will develop from fertilized females and that the males are haploid and the females diploid. It is believed that this form of development may be considered advantageous to transfer because a single female, fertilized or not, could ultimately establish a complete colony of mites on a new host. The span of time per stage or for the entire life cycle is not assurred for any species of Demodex (Nutting, 1983). </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>auratus</i></span><span style="font-size: medium;"> of the golden hamster, </span><span style="font-size: medium;"><i>Mesocricetus</i></span><span style="font-size: medium;"><i>auratus</i></span><span style="font-size: medium;">, can build up to large numbers of all life stages in 35 days; </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>follicularum</i></span><span style="font-size: medium;"> has been estimated to complete its cycle in 14 ½ days; and </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>caprae</i></span><span style="font-size: medium;"> has been estimated to undergo a complete cycle in several to 15 weeks (Nutting, 1983). Morris (1996) suggests that a cat which began to cohabitat with two infested cats contracted its infestation from these already infested cats.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>PATHOGENESIS AND CLINICAL SIGNS:</b></span><span style="font-size: medium;"> In the 13 cases of demodicosis due to the unnamed species of </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;">, Chesney (1989) considered 10 of the cases to represent generalized demodicosis. The 3 cases described by Guaguère (1993) were all of the localized type; while in the 3 cases described by Morris (1996), numerous mites were obtained from superficial skin scrapings of multiple sites on all animals. This mite typically induces pruritis, excessive grooming, alopecia, scaling, hyperpigmetation, erythema, and excoriation associated with self-abuse with signs suggestive of flea allergy dermatitis, atopy, immune-mediated or eosinophilic skin disease, food allergy, contact dermatitis, notoedric mange, or diabetic neurodermatitis (Foley, 1995). </span></p> <p align="JUSTIFY"><span style="font-size: medium;"> Many of the cases of infestation with the unnamed species of Demodex have been diagnosed after treatment with corticosteroids for the initial presentation of skin lesions, e.g., Chesney (1988); Conroy </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">. (1982); Medleau </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">. (1988); Morris (1996); Wilkinson (1983). Morris (1996) felt that exogenous corticosteroid therapy as an immunosuppressive factor must remain speculative. Signs in one of his three cases appeared prior to the corticosteroid injections and the signs resolved after lime-sulfur treatment. Two other cases were shown to actually have developed in cats that had an underlying food allergy. Human cases of demodicosis have developed following the long-term administration of corticosteroid therapy (Hakugawa, 1978; Sato </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">., 1965); and rosacea-like demodicosis has been reported in HIV-positive children (Barrio </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">., 1996). It is assumed that the mites are already present in these cases and that the immunotherapy causes the mites to increase in numbers.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>TREATMENT:</b></span><span style="font-size: medium;"> Foley (1995) recommends that cats infested with the unnamed species of feline Demodex be treated with parenteral ivermectin (300 </span><span style="font-family: 'WP MathA';"><span style="font-size: medium;"></span></span><span style="font-size: medium;">g ivermectin per kg bodyweight) along with 2.5% l;ime-sulfur immersion. He believes the mite is vulnerable to treatment with the lime-sulfur regimen alone in many cases because of this mites localization in the stratum corneum. Foley states that the prognosis for cats infested with this mite is good.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>EPIZOOTIOLOGY:</b></span><span style="font-size: medium;"> Very little is known about the epizootiology of these mites. The report by Morris (1996) would suggest that infestations can be transferred between cats, but this has not been demonstrated in other situations.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>HAZARDS TO OTHER ANIMALS:</b></span><span style="font-size: medium;"> It is believed that this mite is specific for the fieline host.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>HAZARDS TO HUMANS:</b></span><span style="font-size: medium;"> It is believed that this mite does not infest humans.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>CONTROL AND PREVENTION: </b></span><span style="font-size: medium;"> Control is by the isolation and treatment of infested cats. It is expected that cats are infested while nursing although there is no direct evidence that this occurs.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>REFERENCES:</b></span></p> <p align="JUSTIFY"><span style="font-size: medium;">Barrio J, Lecona M, Hernanz JM, Sanchez M, Gurbindo MD, Lazaro P, Barrio JL. 1996. Rosacea-like demodicosis in an HIV -positive child. Dermatology (Switzerland) 192:143-145.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Carlotti D, Lemaire C, Lavayssiere J, Magnool JP. 1986. Le demodecie feline. A propos de troius cas. Prat Med Chir Anim Comp 21:203-208.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Chesney CJ. 1988. An unusual specis of demodex mite in a cat Vet Rec 123:671-673.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Chesney CJ. 1989. Demodicosis in the cat. J Small Anim Pract 30:689-695.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Conroy JD, Healey MC, Bane AG. 1982. New </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"> sp. infesting a cat: a case report. J Am Anim Hosp Assoc 18:405-407.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Foley RH. 1995. Feline Demodicosis. Comp Cont Ed Pract Vet 17:481-487.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Gabbert N, Felkdman BF. 1976. Feline demodex. Fel Pract 6:32-33.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Guaguère E. 1993. Démodécie féline: étude réetrospective de 9 cas. Prot Med Chir Anim Comp 28:31-36.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Hakugawa S. 1978. </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>folliculorum</i></span><span style="font-size: medium;"> infection on the face - abnormal parasitis of </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>folliculorum</i></span><span style="font-size: medium;"> observable with persons using topical steroid preparastion habitually on the face. W Jap Dermatol 40:275.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Keep JM. 1981. Feline dermatoses. University of Sydney Post-Graduate Federation in Veterinary Science.. Sydney.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">McDougal WJ, Novak CP. 1986. Feline demodicosis caused by an unnamed </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"> mite. Comp Cont Ed Pract Vet 8:820-822.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Medleau L, Brown CA, Brown SA, Jones CS. 1988. Demodicosis in cats. J Am An Hosp Assoc 24:85-91.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Morris DO. 1996. Contagious demodicosis in three cats residing in a common household. J Am An Hosp Assoc 32:350-352.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Muller GH. 1983. Feline demodicosis. </span><span style="font-size: medium;"><span style="text-decoration: underline;">In:</span></span><span style="font-size: medium;"> Current Veterinary Therapy, Volume VIII. WB Saunders, Philadelphia, pg 487.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Nutting WB. 1983. Biology and pathology of hair follicle mites (Demodicidae). </span><span style="font-size: medium;"><span style="text-decoration: underline;">In:</span></span><span style="font-size: medium;"> Cutaneous infestations of man an animal. Parsih LC, Nutting WB, Schwartsman RM (eds). Praeger, Nerw York, NY, pgs 181-199.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Nutting WB, Rauch. 1958. </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"><i>criceti</i></span><span style="font-size: medium;"> n. species (Acarina: Demodicidae) with notes on its biology. J Parasitol 44:328-333.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Nutting WB, Satterfield LC, Cosgrove GE. 1973. </span><span style="font-size: medium;"><i>Demodex</i></span><span style="font-size: medium;"> sp. infesting tongue, esophagus, and oral cavity of </span><span style="font-size: medium;"><i>Onychomys</i></span><span style="font-size: medium;"><i>leucogaster</i></span><span style="font-size: medium;">, the grasshopper mouse. J Parasitol 59:893-896.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Sato Y, Higuchi H, Saito U. 1965. Demodectic eczematoid eruption on the face of a boy receiving a long-term corticosteroid treatment. Jap J Dermatol 75:331.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Trimmier WR. 1966. Demodicosis in a cat. Southwest Vet 20:57-58.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">White SD, Ihrke PJ. 1983. Feline Medicine. Pratt PW (ed). American Veterinary Publications, Inc. Santa Barbara, CA. Pg 541.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Wilkinson GT. 1983. Demodicosis in a cat due to a new mite species. Fel Pract 13:32-35.</span></p> <p align="JUSTIFY"></p>
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