The prevalence of Trichophyton mentagrophytes and Cheyletiella spp. in guinea pigs in Dutch petshops

Abstract

Dermatophytes form a group of closely related fungi that can cause disease in animals and man by invading hairs, skin and nails. They use keratin for their growth. Dermatophytosis is an important zoonotic disease. The source of human infections usually originates from a lower animal source and in some research projects Trichophyton mentagrophytes was the most frequently isolated dermatophyte with the guinea pig as a main source. Most guinea pigs infected with T. mentagrophytes are asymptomatic carriers and do not show clinical signs. Skin lesions, which usually start on the head and then progress over the back, flanks and limbs, however, do occur. These skin lesions are pruritic in guinea pigs, just as they are in man, in which pruritus and the specific ‘ringworm’ lesion are the main symptoms.

Little is known about the number of infected guinea pigs (carriers and clinical cases) in the Netherlands. Outside the Netherlands prevalence’s of 1.4% to 34.9% were found.

The aim of this study was to determine the prevalence of T. mentagrophytes in guinea pigs in Dutch pet shops. 179 guinea pigs in 88 pet shops without skin lesions were examined. In 17.3% of the guinea pigs and in 27.3% of the total number of pet shops T. mentagrophytes was isolated. The A. benhamiae-complex was isolated in 29 of 31 positive guinea pigs and the A. vanbreuseghemii-complex of the T. mentagrophytes-complex was isolated in 2 of the 31 positive guinea pigs. T. mentagrophytes was predominantly found in the Northern and Western parts of the Netherlands. Furthermore, neither a significant sex, breed or age predisposition, nor a significant correlation of infection with T. mentagrophytes and hairtype, cage-occupation, turnover-rate, origin, exchange of bowls and coupling/combining of animals were found.

Cheyletiella is an on the surface of the skin living mite, which is a common parasite in dogs, cats and rabbits. Since it does not have extreme host specificity, it can also infect guinea pigs and humans. Cheyletiella is an obligate parasite which completes its life cycle in approximately 35 days on the skin surface. The mite is transmitted by direct contact. In rabbits the severity of clinical signs ranges from asymptomatic to moderate. Since little is known about the prevalence of the zoonotic ectoparasite Cheyletiella parasitovorax in Dutch pet shops and this ectoparasite can enhance susceptibility for Trichophyton mentagrophytes infections, the guinea pigs examined for Trichophyton mentagrophytes were also examined for the presence of Cheyletiella, but no ectoparasites were found.

This study shows that in a quarter of the Dutch pet shops guinea pigs are being sold which are a zoonotic risk of dermatophytosis in humans and that in Dutch petshops Cheyletiella is a very uncommon parasite in guinea pigs.