Cheyletiella spp

From Cat
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Cheyletiella yasguri adult
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Adult C. blakei mite
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Typical dandruff and self-induced alopecia in Cheyletiella infestation in a cat
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Chronic Cheyletiella infestation in a cat

Cheyletiellosis is a very contagious but rare zoonotic parasite of cats caused by the dermal mite Cheyletiella spp[1].

Cheyletiella spp are contagious surface-living mites most often affecting the dorsal trunk of cats[2]. Three species can affect various hosts: C. yasguri usually affects dogs; C. blakei usually infests cats, and C. parasitovorax affects rabbits. All of these species can transiently affect humans. Experimental transfer of C. yasguri from dogs to rabbits is suggestive of non-host specificity[3].

Life cycle

The physical appearance of the large mite (385 micrometers) microscopically shows four pair of legs and prominent accessory mouth parts that terminate in hooks. The mites are surface dwellers and seldom burrow. They tend to reside on the dorsum of the animal, although anecdotal reports have mentioned their crawling into and out of the nares. The life cycle is 21 days with adult females able to live off the host for up to 10 days[4].

In addition to direct transmission, infestation may occur indirectly via fomites such as leashes, grooming tools, or even other, larger arthropods, such as fleas, lice, and flies. Eggs are bound to hair shafts, which, when shed, can also act as an environmental reservoir of infection[5].

Clinical signs

Scaling and pruritus are the main signs of the disease in cats and this can be confused clinically with other causes of pruritus around the head and neck[6], including:

- other mites (Neotrombicula autumnalis, Notoedres spp, Otodectes spp, Pulex irritans, Lynxacarus radovskyi, Sarcoptes spp)
- fleas - Ctenocephalides felis, Echidnophaga gallinacea, Eutrombicula alfreddugesi
- miliary dermatitis (which includes food allergy dermatitis)
- eosinophilic granuloma complex
- fungal infections, especially Malassezia spp
- breed predispositions, such as hereditary greasy seborrhoea in Persian cats

With Cheyletiella spp infection, the intensity of the pruritus is usually mild to moderate, but sometimes appears disproportionate to the apparent low numbers of mites. Scratching may cause open ulcers around the collar region and hairloss to the thighs which can be confused with overgrooming. This might be due to a hypersensitivity reaction to the mite. An asymptomatic carrier state also exists and this should be borne in mind when tackling problem cases in which repeated reinfestation and zoonotic transmission is occurring. Humans in contact with pets carrying Cheyletiella spp. are at risk of becoming transiently infested themselves, producing an uncomfortable, pruritic dermatosis, characterized by papular lesions that, typically, appear on the arms, legs, trunk, and buttocks. However, as Cheyletiella spp. are not capable of reproducing on humans, appropriate treatment of the pet host should prevent further infestation, making human acaricidal therapy unnecessary[7].

The ease of finding the mite or its eggs is variable. It can be especially difficult in cats because of their natural grooming habits. Diagnosis is made by direct viewing of the mite, microscopic examination of the products of superficial skin scrapings, acetate tape preparations or flea combing (with or without dissolution of hair and debris with KOH), or faecal flotations. The “KOH and flotation technique” has been reported to be one of the most reliable methods. Although not performed very frequently, faecal flotation may indeed be particularly useful for the detection of ingested mites and ova in cats, due to their grooming habits. In many cases, the diagnosis can be confirmed only by the response to treatment with an acaricidal trial. Moreover, an appropriate acaricidal trial is always required in order to rule out cheyletiellosis[8].

Treatment

Treatment duration, which should cover a minimum period of 6 to 8 wk, is directly influenced by the severity of the infestation, the number of animals involved, the acaricidal product chosen, and whether or not there is concomitant topical or environment decontamination, or both[9]. Weekly bathing in pyrethrin shampoo has shown efficacy, although in catteries, may be impractical.

Lime sulfur dips have been popular in the past, given every five to seven days for three weeks[10].

Fipronil spray is a highly effective at eliminating this parasite in cats[11].

Ivermectin and selamectin topically one dose every 15 days for a total of three months[12][13][14]. Ivermectin given at 200 micrograms/kg every week for three weeks (must be heartworm negative first and not used in herding breeds or crosses thereof — also avoid ivermectin in older patients).

Milbemycin 2 mg/kg once weekly for three weeks (one study treated for up to nine weeks)[15]

References

  1. Moriello KA (2003) Zoonotic skin diseases of dogs and cats. Anim Health Res Rev 4(2):157-168
  2. Euguere, E & Prelaud, P (2000) A practical guide to feline dermatology. Merial, France
  3. Scott DW et al (2001) In: Muller & Kirk's Small Animal Dermatology, 6th ed, Philadelphia; WB Saunders. pp:423–516
  4. Paradis M. Mite dermatitis caused by Cheyletiella blakei. J Am Acad Dermatol 1998;38:1014–1015
  5. Wagner R & Stallmeister N (2000) Cheyletiella dermatitis in humans, dogs and cats. Br J Dermatol 143(5):1110-1112
  6. Curtis CF (2004) Current trends in the treatment of Sarcoptes, Cheyletiella and Otodectes mite infestations in dogs and cats. Vet Dermatol 15(2):108-114
  7. Paradis M, Scott DW, Villeneuve A (1990) Efficacy of ivermectin against Cheyletiella blakei infestation in cats. J Am Anim Hosp Assoc 26:125–128
  8. Wagner R, Stallmeister N. (2000) Cheyletiella dermatitis in humans, dogs and cats. Br J Dermatol 143:1110–1112
  9. Shanks DJ, McTier TL, Rowan TG, et al (2000) The efficacy of selamectin in the treatment of naturally acquired aural infestations of Otodectes cynotis on dogs and cats. Vet Parasitol 91: 283–290
  10. Schwassman, M & Logas, D (2010) how to treat common parasites safely. In August, JR (Ed): Consultations in feline internal medicine. Vol 6. Elsevier Saunders, Philadelphia. pp:390
  11. Scarampella F et al (2005) Efficacy of fipronil in the treatment of feline cheyletiellosis. Vet Parasitol 129(3-4):333-339
  12. Chailleux, N & Paradis, M (2002) Efficacy of selamectin in the treatment of naturally acquired cheyletiellosis in cats. Can Vet J 43:767
  13. Fisher MA & Shanks DJ (2008) A review of the off-label use of selamectin (Stronghold/Revolution) in dogs and cats. Acta Vet Scand 50:46
  14. Chailleux N & Paradis M (2002) Efficacy of selamectin in the treatment of naturally acquired cheyletiellosis in cats. Can Vet J 43(10):767-770
  15. Pagé N, de Jaham C, Paradis M (2000). Observations on topical ivermectin in the treatment of otoacariosis, cheyletiellosis, and toxocariosis in cats. Can Vet J 41:773–6