Prevalence of Chorioptes sp. mite infestation in alpaca (Lama pacos) in the south-west of England: implications for skin health

A study aiming to determine the prevalence of Chorioptes sp. mite infestation in the alpaca (Lama pacos) was carried out following confirmation of widespread skin disorders affecting South American camelids in the United Kingdom, and the isolation of this species of mange mite in conjunction with skin lesions from case material referred to the authors. A total of 209 alpaca in nine units in the south-west of England were included in the study. Every alpaca on the unit was clinically examined for the presence of skin lesions. All alpaca presenting with signs of skin disease, as well as approximately one in five clinically healthy, randomly selected, in-contact alpacas were included in the sampled population (n = 83). Superficial skin scrapings were taken from each animal included in the sampled population from six different sites, in addition to a dry swab taken from the ear canal. Of the 209 alpaca examined, 47 (47/209; 22.5%) showed signs of skin disease, ranging from mild alopecia, thickening, crusting and scaling of the skin of the pinnae, to severe and similar diffuse lesions affecting mostly ears, axilla, face and dorsum. Of the sampled population, 33 alpaca (33/83; 39.8%) were positive for Chorioptes sp. mite. Cumulatively, in 29 out of 33 positive cases (87.9%) Chorioptes sp. mites were detected in scrapings taken from the forefoot and/or the axilla. Thirteen out of the 47 alpacas affected by skin lesions (27.7%) were concurrently positive for Chorioptes sp. mite, 20 out of 36 (55%) un-affected sampled alpaca were positive for the mite, and 34 out of 47 affected alpacas (72.3%) presented skin lesions but were negative for Chorioptes sp. mite. Statistical test showed that affected animals tended not to be positive for the mite whilst un-affected animals tended to be positive for the mite. Additionally, there was a highly significant association between lesions, age and mite, in that an increase in the presence of skin lesions and a decrease in the presence of mites with increasing age was observed. Chorioptes sp. mites have been previously observed in the llama and the alpaca, but chorioptic mange was considered a rare condition in both host species. Findings from the present study indicate high prevalence of both the mite infestation and related clinical signs in alpaca in the south-west of England.