A molecular technique for the detection and differentiation of Demodex mites on cats

Abstract

Demodex gatoi causes a pruritic dermatitis in cats. Diagnosis requires the demonstration of mites using superficial skin scrapings or faecal flotation, which can be insensitive. The goal of this study was to develop a molecular method to diagnose D. gatoi infection in cats and distinguish these mites from Demodex cati. Fifty-three shelter cats, 11 cats from a closed research colony and 12 privately owned cats were used. Demodex gatoi and D. cati were obtained from scrapings of cat skin. The 16S rRNA DNA was amplified by PCR, sequenced and compared with available Demodex sequences. Hair and skin samples were also collected for microscopic examination and DNA isolation. DNA sequences were obtained from D. gatoi and D. cati. qPCR with D. gatoi specific primers and probe amplified DNA isolated from D. gatoi and not D. cati. Conversely, D. cati qPCR primers and probe amplified D. cati DNA and not D. gatoi. Five of the shelter cats were positive for D. gatoi. Two of these cats were pruritic, and the other three were in contact with these cats. Only one cat was positive for D. gatoi on skin scraping but was negative for D. gatoi or D. cati DNA. Results from this study show D. gatoi and D. cati to be distinct species. A novel qPCR test for the identification and differentiation of D. gatoi and D. cati was developed. Once optimized, this test could provide a valuable technique for the diagnosis of D. gatoi infection.