Incidence of Mediterranean Spotted Fever in Sicilian children: a clinical-epidemiological observational retrospective study from 1987 to 2010

Background: Zoonoses are human infectious diseases caused by pathogens that primarily infect animals. Mediterranean Spotted Fever (MSF) represents one such example, affecting the Mediterranean region, in which household animals can be immune-carriers of infected ticks. Materials and methods: We retrospectively analysed the incidence and the clinical and laboratory features of MSF caused by R.Conorii in children admitted to the Paediatric Operative Unit from 1987 to 2010, for persistent fever and generalised macular-popular erythematous lesions. Clinical, immunological and serological parameters of 55 cases of Rickettsia infections observed in children between 2 and 11 years of age were collected. Results: We found an increasing incidence of MSF in childhood from 1987 to 2010. Diagnosis of MSF at the moment of hospital admission was done in 16 patients (29.09%). The presence of the typical Tache noire was observed in 16 cases out of 55 patients (29.09% of cases). We noticed a different representation of R. conorii antigens in serological testing over the time period of the study, corresponding to overall higher incidence rates for infection in the latter years. We also observed a higher incidence of infection in those years in which all four antigens were found positive at serum testing with respect to those years in which only two of the four antigens were observed (1987-1990: 0-16%; 2007-2010: 0.46%; P<0.005). Conclusions: These changes in R. conorii antigenicity may be the cause of higher pathogenicity in this parasite, perhaps linked to increased immigration along with consequent changes in the epidemiology of infectious diseases in host countries