OutbreaksandEpidemics
Notable epidemic and outbreak episodes due to dermatophytes are considered to be rare, especially compared with other pathogens, such as bacteria and viruses. For instance, GIDEON (Global Infectious Disease and Epidemiology Network) database
(http://www.gideononline.com/) reports 1267 outbreaks (with approximately 275,000 patients involved) of diarrhea by Escherichia coli in an 82-year period (1934-2016) and 140 outbreaks (with approximately 9600 patients involved) of dermatophytosis in a 133-year period (1882-2015).
Of these latter, 25 episodes (18%) were due to M. canis and distributed worldwide. This discrepancy between the number of reported outbreaks and real significance of dermatophytes is due to many factors. The episodes occur in different contexts and usually with a limited number (less than 20) of people/animals involved, but in some occasions numbers are much higher. Outbreaks in households and animal communities are frequent worldwide, although they are hardly reported in the literature because dermatophytosis, both in humans and animals, is not a notifiable disease in most countries. Among factors that contribute to the occurrence of such episodes, one of the most important is the poor awareness of people about the role of animals, especially pets, as carriers of dermatophytes. Indeed, in most cases, infected animals are introduced and manipulated without any precaution (e.g., a quarantine period, a veterinary visit, etc.) and left free to stay with animals already present in the house, breeding, pet shop, etc. Significant changes in epidemiological patterns on the large geographic areas take place on relatively long time scale (years and decades) and are detectable only when long-term epidemiological data are available what is an uncommon condition in veterinary dermatology. Additionally, changes in the prevalence of dermatophytosis can be easily neglected in principal hosts of particular pathogens because infections are commonly asymptomatic in high percentage of infected animals. The screening should therefore include ostensibly healthy animals as well.Exceptionally, extensive changes in the epidemiology happen very quickly. For instance, the emergence and rapid spread of T. benhamiae in Europe have been one of major public health events in the field of zoonotic superficial mycoses in recent years that underscored the need for closer collaboration between the veterinary profession, dermatologists, epidemiologists, and public health personnel. Zoonotic infections associated with pet shops are likely to result in individual cases or small familial outbreaks. On the other hand, an infected animal kept in a group in a pet shop can potentially transmit the illness to other animals, and subsequently to a large number of pet owners, who may be geographically dispersed (Halsby et al. 2014). Because of this, pet shops can be the focus of large outbreaks, such as in the case of recent epidemics of T. benhamiae infections in pediatric patients. Epidemiological surveys in different European countries showed that ~17-90% of guinea pigs (commonly asymptomatic) in pet shops are infected. This resulted in high incidence of tinea corporis and capitis in children and young adults in affected countries. The first human infections started to occur in different European countries between 2000 and 2010, and it seems that the incidence has not yet reached its peak. For instance, in Germany and Czech Republic, T. benhamiae became within several years the most important agent of zoonotic dermatomycoses at all (Hubka et al. 2014b; Uhrlaβ et al. 2015).
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