T. mentagrophytes, T benhamiae and Guinea Pigs: What’s the connection?
T. benhamiae and T mentagrophytes are both common in guinea pigs and guinea pigs often harbour these fungi asymptomatically. Most guinea pigs infected with Trichophyton mentagrophytes fail to develop clinical signs and become asymptomatic carriers of the fungus. The prevalence of Trichophyton mentagrophytes infection ranges from 1.4 to 34.9% in these animals.
In a study published in 2013 by Hiruma et al, Trichophyton mentagrophytes was isolated from 19 out of 20 completely asymptomatic guinea pigs housed in a zoo in the city of Urayasu, Japan.
In 2019, Bartosch et al. demonstrated that, in a group of 41 animals housed together (rabbits, rats, mice and guinea pigs), 18 out of 26 guinea pigs had dermatophytosis, although only 11 showed clinical signs. Of 18 confirmed cases, 11 were caused by Trichophyton mentagrophytes and 15 were due to T benhamiae. 8 of the guinea pigs had both types. Dermatophytosis was less common in the other animals and rabbits were not affected at all.
The prevalence of zoonotic T. benhamiae infections has increased worldwide over the last 15 years. T benhamiae has spread ubiquitously to guinea pigs since the turn of the millennium and is an emerging problem. In a study in 2016, T. benhamiae was isolated in more than 90% of (55 of 59) of the guinea pigs sampled in 15 pet shops in Berlin (Kupsch, 2017). Overall, it’s estimated that 50-90 % of guinea pigs have T benhamiae. Just like with T mentagrophytes, a large proportion of guinea pigs are completely asymptomatic.
Consultation with a vet is important for guinea pig owners to determine asymptomatic carriage. Topical treatments are available to help erradicate fungi.
Understanding the unique dermatophytes transmitted by guinea pigs is important. According to Kaveecage.com, there are an estimated 3.8 million guinea pigs in the United States, 1.5 million in Germany, 800,000 in the UK, 800,000 in France and about half a million in each of Canada, Spain and Italy
REFERENCE
Cukierman E et al. Alopecia and pet: a case report. Einstein (Sao Paulo). 2022 Jul 4;20:eRC6881.
Hiruma J, Kano R, Kimura U, Takamori K, Suga Y, Hiruma M et al. Mating type gene for isolates of Trichophyton mentagrophytes from guinea pigs. J Dermatol. 2014;41(8):743-45.
Kupsch C, Ohst T, Pankewitz F, et al. “The agony of choice in dermatophyte diagnostics—performance of different molecular tests and culture in the detection of Trichophyton rubrum and Trichophyton interdigitale” Clinical Microbiology and Infection (2016) 735.e11-735.e17
Bartosch T, Frank A, Günther C, Uhrlaß S, Heydel T, Nenoff P et al. Trichophyton benhamiae and T. mentagrophytes target guinea pigs in a mixed small animal stock. Med Mycol Case Rep. 2018;23:37-42.
