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British Veterinary Camelid Society
Proceedings of 2005 conference
Ectoparasitic diseases of South American camelids
Aiden P Foster PhD, DipACVD, MRCVS The most common causes of parasitic skin disease in camelids include: Easily identified by their characteristic shape and leading to pruritus with matted wool and alopecia in heavy infestations. There are 2 main types: Sucking lice (Microthoracius sp) affecting the head, neck and withers. Sucking lice may respond
to ivermectin or moxidectin;
Biting lice (Bovicola breviceps) affecting the base of the tail and along the neck and trunk.
Biting lice can be treated with topical therapies such as spot-on/pour-on deltamethrin, fipronil,
diazinon, spinosad, insect growth regulators, OPs.
Psoroptes mites
Pruritus and fibre loss is particularly associated with the pinnae and ear canal, but the shoulders, back, sides, tail head, perineum, nares, axillae, groin, neck and legs can also be affected. Could camelids be a potential reservoir for sheep scab mites? Sarcoptes mites
Sarcoptes scabiei var auchinae causes intense pruritus with hyperemia, papules and pustules with crusting. There is a generalised distribution including the limbs especially between the toes, medial thighs, ventral abdomen, chest, axillae, perineum and prepuce. Remember the zoonotic risk. It generally responds well to treatment.
Chorioptes mites
Chorioptes bovis causes mild pruritus, alopecia and scaling of the feet and tail base, with possible extension to the ventral abdomen, medial limbs, and the ears. Llamas have also been seen with lesions on the head, ears and perineum.
Previous studies include d.Alterio et al (2005) Prevalence of Chorioptes sp. mite infestation in alpaca (Lama pacos) in the south-west of England: implications for skin health. Small Ruminant Research 57: 221-228.
This showed that 47/209 (22.5%) had signs of skin disease and chorioptes mites were identified from 33/83 (40%). Of these, 40% were showing concurrent skin lesions (13/33) and 55% of animals with no lesions also tested positive for mites (20/36). In 88% of positive cases (29/33) mites were detected from the forefoot and/or the axilla. Superficial skin scrapes of the interdigital areas are most likely to yield positive results.
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British Veterinary Camelid Society
Proceedings of 2005 conference
Macrocyclic lactone-based products do not seem to be very effective for treatment of chorioptic mites. If used, best advice is to use higher than label doses of ivermectin for ectoparasites in alpacas and llamas, eg 400� Animals should be weighed to allow accurate dosing and the whole herd should be treated. Chorioptes mites feed on epidermal debris, so topical treatment eg with fipronil spray may have a better effect, but there could be practical issues with administration. For psoroptic and sarcoptic mange or sucking lice, ivermectin at 200� injection has a variable but usually good effect. Also use in combination with fipronil for concurrent infections of chorioptes and sarcoptes in llamas.
Pharmacokinetics of ivermectin and moxidectin in the dromedary camel were compared with studies in cattle and sheep. It seems as if camelids do not absorb ivermectin (oral or injectable) as well as ruminants. However, there has been successful treatment of alpacas with lice, sarcoptic and psoroptic mange with two injections of moxidectin seven to 10 days apart.
As camelid fibre does not contain lanolin, it could be that there is little residual effect which is
why topical applications of insecticidal/acaricidal products used in other ruminants may not be as
effective in camelids. See d’Alterio, et al. (2005) Comparative study of the efficacy of eprinomectin
versus ivermectin, and field efficacy of eprinomectin only for the treatment of Chorioptes mange
in alpacas. Veterinary Parasitology 130: 267-275. There is a need for pharmacokinetic studies
and further controlled clinical trials.
The whole topic of parasitic skin diseases in camelids, particularly alpacas, raises several questions. What is the association with: Chronic chorioptes infestation? – an allergic response in certain individuals to chorioptic
mange? Is severe skin disease due to an allergic response to mite products? Problems associated
with intradermal skin testing include the need to remove the fibre, which antigen to use and
how to produce positive controls. What about detection of mite specific IgE antibodies in the skin
(IDT) or the circulation (allergen specific IgE serology or ASIS)? However, a positive test may
indicate prior exposure rather than current infestation, and may not represent a hypersensitivity
response in that individual.
Zinc metabolism? - orthoparakeratosis and parakeratosis with thickening, superficial dermatitis
and dermal infilatrate, can be associated with zinc related disorders such as zinc responsive
dermatosis. However, work done by Clauss et al in 2004 (Veterinary Journal 167, 302-305)
showed that all the animals studied, regardless of skin lesions, had low zinc and copper levels,
but only 1/35 responded to zinc supplementation.
Discussion after the presentation
None known. Many would be unsure about trying it.
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British Veterinary Camelid Society
Proceedings of 2005 conference
Comments
An alpaca herd in New Zealand had a severe problem which appeared to clear after serial OP dipping every 10 days for six weeks, but recurred within a further six weeks.
The big issue is that this condition is very difficult and frustrating to treat.
Perhaps this could be a hypersensitivity reaction to culicoides as in goats and sheep.
In really severe cases with profound hyperkeratosis, pruritus decreases as nerve endings become more damaged.
Various advice including: clip, treat with ivermectin or eprinomectin + a topical product for full coverage; encourage the owner to wash badly affected individuals to get rid of the mites and soothe inflamed skin.
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