Current Advice on Parasite Control:
Ectoparasites - Hairclasping Mite
• Cheyletiella spp. are also referred to as “walking dandruff” mites.
Overview of Life Cycle
- Adult Cheyletiella spp. are nonburrowing and live on the skin, where they feed on the keratin layer of the epidermis. Cheyletiella blakei also feeds on the hair coat of the cat.
- Cheyletiella spp. are very mobile and are contagious by direct contact. These mites have been found on fleas, lice, and flies; it has been hypothesized that this is one means by which they move between hosts.
- Lynxacarus radovskyi are laterally compressed and found clinging to the hairs of the cat. The large eggs (200 μm in length) are glued to the hairs and produce a six-legged larva. The larva molts to an eight-legged nymph, which molts to the adult.
- Cheyletiella spp. developmental stages include egg, prelarva, larva, a first and second nymphal stage, and adult. Eggs are very large (about 240 μm long) and glued to the hairs. The prelarva is a quiescent nonfeeding stage that appears to be no more than a legless sack. Adult Cheyletiella spp. are large, 500 μm long, and visible to the unaided eye. The key morphologic features are the large palpal claws.
- Lynxacarus radovskyi eggs are about 200 μm long and are attached by one end to the hairs of the cat. The six-legged larvae and eight-legged nymphs are also found on the hairs of the cat. Adult Lynxacarus sp. mites are about 500 μm long, laterally compressed, and have short legs anteriorly on the first two-thirds of the body. They are found clinging to the hairs with the anterior end held near the hair shaft.
- Infestation with Cheyletiella spp. causes exfoliative dermatitis with flaky, bran-like squames that is seen principally on the dorsum. The visual appearance of “walking dandruff” is caused by the agitation of epidermal debris by the activities of the mites. Cats sometimes develop miliary dermatitis with reddish yellow crusts.
- In Lynxacarus sp. infestations, mites most commonly are found on the tail head and tip and in the perineal area. In heavy infestations, mites may be found over the cat’s entire body. The hair coat can appear dull, dry, and rust-colored. The mites and eggs present on the hairs give the cat a “peppered” appearance, and the coat may be granular to the touch. Cats may present with gastrointestinal disturbances, rectal irritation, or hairballs due to excessive grooming. In addition, infested cats may have gingivitis, anorexia, restlessness, fever, and weight loss.
- Cheyletiella spp. infestations, though relatively uncommon, seem to occur most often on puppies from large breeding facilities.
- Lynxacarus sp. infestations in cats are rare in most parts of the United States but can be common in more tropical regions, such as Hawaii, Puerto Rico, and the Florida Keys. The mite is also found in Fiji and Australia
Host Associations and Transmission Between Hosts
- Species of hairclasping mites appear to be restricted to their respective hosts.
Prepatent Period and Environmental Factors
- In the case of cheyletiellosis, it takes 3 to 5 weeks for an infestation to develop from a single mite.
- Lynxacariasis development is not as well described but is considered to be 3 to 5 weeks.
Site of Infection and Pathogenesis
- Cheyletiella spp. mites and associated lesions typically are found on the dorsum.
- Cases of lynxacariasis typically are associated with the numerous mites clinging to the hairs and the associated pruritus induced by their presence.
- Mites typically can be found upon observation and identified by their distinct appearance. An examination of the skin with a hand lens often will clearly reveal the mites.
- Mites sometimes are found in the feces of cats that have groomed the mites from their body surface.
- Specific identification can usually be made by the host association. Specific morphologic diagnosis of the Cheyletiella spp. can be made by very close examination of the shape of a seta on the fourth pair of legs; the seta is heart-shaped in C. yasguri and conical in C. blakei.
- There are no treatments labeled for hairclasping mites in the United States.
- A number of different treatments have been shown to be effective against hairclasping mites, including high-dose ivermectin, milbemycin oxime, moxidectin, selamectin, fipronil, and pyrethrin shampoos.
Control and Prevention
- Infestations in cats and dogs can be prevented by routine administration of topical moxidectin, selamectin, or fipronil on a monthly basis.
Public Health Considerations
- Skin lesions may develop on people in contact with infested dogs or cats. Zoonotic infestations are more commonly reported from cat owners than dog owners, a phenomenon that may be attributable to the mite’s behavior or differences in likelihood of close contact with an infested pet.
- Lynxacarus radovskyi has not been associated with skin lesions on the owners of infested cats.
- Arther RG. 2009. Mites and lice: biology and control. VCNA Small Anim Pract. 39: 1159-71.