IN HUMANS continued
CLINICAL DISEASE • Human infestations with S. scabiei var. canis are usually self-limiting. It generally manifests in areas of contact associated with the affected dog, such as the forearms, thighs, chest and abdomen. 13 Lesions associated with S. scabiei var. canis are more limited in extent and duration than that of S. scabiei var. hominis. • The rash and irritation associated with scabies in humans due to canine associated Sarcoptes mites shows features of both type I (immediate) and type IV (delayed) hypersensitivity reactions. • Human scabies induced by the canine mite can result in a highly pruritic papulovesicular rash that can last for several weeks, but which typically resolves spontaneously (whereas human scabies can last several years without treatment). Human infestation with the canine strain of Sarcoptes can be evident within 24-96 hours of contact with an affected pet. 13 In contrast, the incubation period of S. scabiei var hominis following initial exposure is 3-6 weeks, as clinical signs are in part due to a hypersensitivity reaction to the mite. 14 With subsequent exposure the incubation period may be as short as 1-3 days. • In some cases, hyperinfestation of mites can occur due to an inadequate immune response (e.g. immunosuppression, including advanced HIV) and/or inadequate ability to react or seek treatment (e.g. in patients with dementia). Known as
Cutaneous lesions due to the transmission of Sarcoptes scabiei from a dog to its owner
‘crusted scabies’, this condition presents as hyperkeratotic dermatosis, often with deep skin fissures, and is highly contagious due to a significantly higher mite burden. 15 Crusted scabies requires longer courses of systemic therapy such as ivermectin, rather than topical preparations (permethrin cream). Crusted scabies due to Sarcoptes scabiei var. canis has been reported very rarely in the literature. 16 It is usual practice to treat all significant contacts.
• Diagnosis in humans can be made by microscopy of skin scrapings. When the mite is not detected on microscopy, response to treatment can be considered diagnostic.
KEY CONSIDERATIONS 1. Human scabies is mostly associated with the host adapted variety S. scabiei var. hominis after direct human-to-human transmission, however zoonotic infestation with S. scabiei var. canis from dogs may occur. 2. Human infestation with S. scabiei var. canis is typically self-limiting and the lesions of a more limited extent and duration compared to infestation with the human host-adapted variety. 3. Owners of infested pets should seek medical advice if they develop any cutaneous lesions.
An all year-round parasite control program in dogs with a parasiticide
registered to treat and control mites and other ectoparasites is recommended, particularly in areas with a high prevalence of sarcoptic mange.
References: 1. DeCandia, A.L., et al (2019) Of microbes and mange: consistent changes in the skin microbiome of three canid species infected with Sarcoptes scabiei mites. Parasit Vectors , 12(1), 1-10. 2. Beveridge, I., et al (2015) Australasian Animal Parasites: Inside and Out. Australian Society for Parasitology . 3. Saari, S., et al (2018) Canine Parasites and Parasitic Diseases . Academic Press. Chapter 9 - Arachnida, 187-228. 4. Beugnet, F., et al (2018) Textbook of clinical parasitology in dogs and cats . Servet editorial-Grupo Asís Biomedia, SL. 5. Arlian, L.G., et al (2017) A review of Sarcoptes scabiei: past, present and future. Parasit Vectors, 10, 297. 6. Craig, M., (2014) Disease facts: canine sarcoptic mange (scabies). Companion Animal , 19(7), 346-348. 7. Diwakar, R., et al (2017) Canine scabies: a zoonotic ectoparasitic skin disease. Int. J. Curr. Microbiol. Appl. Sci , 6, 1361-1365. 8. Pin, D., et al (2006) Localised sarcoptic mange in dogs: a retrospective study of 10 cases. J Small Anim Pract , 47(10), 611-614.
9. Mueller, R., et al (2001) Value of the pinnal-pedal reflex in the diagnosis of canine scabies. Vet Rec , 148(20), 621-623. 10. Chitty, J., et al (2007) Zoonotic skin disease in small animals. In Pract, 29(2), 92-97. 11. Walton, S.F., et al (1999) Genetically distinct dog-derived and human-derived Sarcoptes scabiei in scabies-endemic communities in northern Australia. Am J Trop Med Hyg , 61(4), 542-547. 12. Morrison, D.A., (2005) Networks in phylogenetic analysis: new tools for population biology. Int J Parasitol, 35(5), 567-82. 13. Burroughs, R.F., et al (2003) What’s eating you? Canine scabies. Cutis , 72(2), 107-109. 14. Chosidow, O., (2006) Clinical practices. Scabies. N Engl J Med , 354(16), 1718-27. 15. Chandler, D.J., et al (2019) A review of scabies: an infestation more than skin deep. Dermatology , 235(2), 79-90. 16. Stingeni, L., et al (2020) Nosocomial outbreak of crusted scabies in immunosuppressed patients caused by Sarcoptes scabiei var. canis . Br J Dermatol , 182(2), 498-500.
CONTENTS
Companion Animal Zoonoses Guidelines 78
Made with FlippingBook - professional solution for displaying marketing and sales documents online