The epidemiology of sporotrichosis has undergone major shifts in recent decades.1,2 Recent epidemics have demonstrated the potential for zoonotic transmission of Sporothrix and have nearly always involved cats as the main source of infection.3,4 In this setting, an epidemic of sporotrichosis has been occurring for the last three decades in Abancay province, a poor area in the south central highlands of Peru,5 where several reports have suggested that cats may be a source of infection.6,7 This province is hyperendemic, both among the general population (mean annual incidence, 98 cases per 100,000 inhabitants) and among children <15 years old (mean annual incidence, 156 cases per 100,000 inhabitants).7,8 Since 1982, a steady increase in the number of cases has been reported from the city and surrounding areas, reaching a total of 1503 cases between 1985 and 2012.5 A survey has confirmed that cats in the Abancay province are a large reservoir of Sporothrix. The fungus has been isolated from claw fragments and materials collected from nasal and oral cavities of infected cats.6 These cats harbouring Sporothrix showed no clinical evidence of skin disease. Thus, this situation raises the possibility of zoonotic transmission of Sporothrix from healthy-appearing cats to humans either through direct or close contact with cats or indirectly through exposure to environments that are contaminated by infected cats. Moreover, contact with cats has been shown to be a significant risk factor for sporotrichosis in one case control study.7 For these reasons, many questions related to the mechanism of zoonotic transmission and to the context in which this transmission occurs remain unanswered.
Following these observations, we reanalyzed data from previously published results of a large cohort of cases from Santa Teresa Clinic (STC) of Abancay between 2004 and 2011,5,9 to test the hypothesis that epidemic transmission of sporotrichosis occurs through contact with cats. To explore the epidemic characteristics of sporotrichosis, cases of patients who had contact with cats were compared with cases of traumatic inoculation with infected environmental materials.
From 2004 to 2011, 479 cases of sporotrichosis were recorded in STC, all from different geographic provinces of Apurimac region (Fig. 1A). It is noteworthy that most cases occurred in Abancay province (84%). Of the 479 cases, 39.5% (n=189) reported previous contact with cats, and 21.5% (n=103) described traumatic inoculation with infected materials. There was a statistically significant difference in the risk factors between the two groups (p<0.03, χ2 test) (Fig. 1B). The rest of the patients (187, 39%) could not definitely remember whether they had been exposed to cats or not.
(A) Geographic distribution of cases of sporotrichosis in the region of Apurimac, Peru 2004–2011. The most affected area is Abancay, where the carriage rate of Sporothrix in the cat population is 2.38%.6,9 (B) Distribution of cases of sporotrichosis according to the presence or contact with cats, and traumatic inoculation.
Sixty-five of 189 patients that were in contact with cats, reported experiencing a traumatic injury that preceded the symptoms, consisting of a history of receipt of cat scratch, and 124 patients denied experiencing a traumatic injury before the onset of the disease. The cats involved in the transmission of the disease were not evaluated.
A proportion of the sporotrichosis cases included in the study cohort had previous direct contact with cats, which possibly led to an increased likelihood of infection. Although it is difficult to establish a specific causality, taken together, these data strongly implicate cats as a source of infection. Moreover, these findings suggest that epidemic transmission of sporotrichosis in Abancay is likely to occur through direct contact with cats, rather than through traumatic inoculation with infected materials. Therefore, the province of Abancay in Peru is hyperendemic for cat-associated sporotrichosis. In order to gain better insight into the mechanism of zoonotic transmission of Sporothrix, more epidemiological studies in cats are needed to confirm the association found.
FundingThe author has no support or funding to report.
Conflicts of interestThe author reports no conflicts of interest.
