Molecular detection and characterization of Sarcoptes scabiei var canis using skin scrapings and skin biopsies.

Canine sarcopticosis is a highly infectious and debilitating parasitic skin disease of dogs. Its diagnosis stands challenging as the golden standard of diagnosis; skin scraping microscopy is characterized by several diagnostic variations. Study thus employed several alternate diagnostic approaches using Polymerase Chain Reaction (PCR) on skin scrapings and skin biopsies. Whole Sarcoptes scabiei var canis mites, thirty six "3 cm × 3cm" skin scrapings and 3 mm punch biopsies from six different lesioned sites per infested dog were all obtained from six severely sarcoptes ridden dogs. Samples were mechanically disrupted for DNA extraction and amplification. Positive samples were further commercially sequenced. Amongst the thirty six (36) skin biopsy and scraping samples processed, PCR detected the DNA of Sarcoptes scabiei var canis in thirty two (32) skin biopsy samples with a sensitivity of 88.88%. Twenty five (25) skin scraping samples were also positive for scabies with a sensitivity of 69.44%. The Phylogenetic analysis revealed a relationship between the Sarcoptes scabiei var canis mites from Nigeria and Sarcoptes scabiei of humans, raccoon dogs and rabbits in Pakistan, Japan and Egypt.  The diagnostic errors and false negatives accompanying the skin microscopy diagnostic technique can best be limited with the use of PCR diagnosis on skin scrapings and skin biopsies most especially. This highly sensitive diagnostic tool would certainly and effectively control the menace of sarcopticosis in dogs.

Sequential Histopathological Changes and Cytokine Expressions in Dogs Naturally Infested with Sarcoptes scabiei Mites.

BACKGROUND: The diagnosis and treatment of canine scabies remain quite challenging as a result of the meddling of the invertebrate mite Sarcoptes scabiei var canis with the immunologic activity of its host. PURPOSE: This study aims to evaluate and better understand the immunologic, histomorphometric, histopathologic changes as well as their relationship in scabies infestation. METHOD: Ten healthy dogs were housed with five sarcoptes-ridden dogs. Skin biopsies were then obtained afterwards for 7 weeks into buffered formalin. Sections of obtained biopsies were processed and incubated in IL-4, IL-13, IL-17A and IL-23A antibodies, while the other sections were stained for cellular alterations, quantifications and measurement of tunnel height and diameters. Pearson's product-moment correlation was used to establish the association between the cytokines and the measured tunnel heights and diameters, while Student's t test and one-way analysis of variance were used to test for weekly significant differences in cytokine expressions. RESULTS: Histopathologic changes and early expression of all studied cytokines, eosinophils and mast cells were pronounced from the second week of infestation. Quite notable was the consistent amount of IL-13 and IL-23A all through the study duration. A dissimilar association was also observed between anti-inflammatory cytokines (IL-4 and IL-13) and pro-inflammatory cytokines (IL-17A and IL-23A). Also observed was the negative relationship between IL-13 and IL-23A as an increase in IL-13 was associated with a decrease in IL-23A. Tunnel height increase was also positively associated with pro-inflammation. CONCLUSION: Immunodiagnosis can possibly be achieved with IL-13 and IL-23A expressions, while immunotherapy seems possible with IL-13 cytokine therapy.

Establishment of infestivity model for Sarcoptes scabiei var canis in Nigerian dogs.

Experimental transmission patterns involved with the establishment of mange in dogs were studied to ascertain the effective means of infestation model for mange experiments in dogs. A total of eighteen (18) dogs were used out of which three (3) were naturally infested with Sarcoptes scabie var canis. Five (5) healthy dogs were co-mingled with the three (3) donor dogs for direct contact transmission. Another five (5) mange free dogs were aggregated in a kennel recently vacated by mange infested dogs for environmental and formite transmission while the last five (5) healthy dogs had scrapings from a proximate area of mange lesion sites transferred into the pinnae of each dog for experimental and indirect contact transmission. Successful mite transmission with associated clinical features of pruritus, alopecia, erythema, papules and crusts was achieved with co-mingling of mange naïve and mange infested dogs. These clinical features also differed (p < 0.05) from dogs experimentally infested as this method of transmission was largely unsuccessful. Following the success of the direct contact model closely is the environmental and formite transmission model. Here, healthy dogs were housed in recently vacated mange infested kennels. The direct contact model only differed from the environmental model (p < 0.05) in the expression of erythema and papules in dogs. Although comingling infested and mange naïve dogs guarantees successful direct contact transmission, exposure of healthy dogs to infested facility would also lead to infestation. This study showed that comingling remain an effective means of infestation model for mange experiments in dogs.