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

• 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.
• Data from the Italian National Statistic Institute (ISTAT) show that of 1489 cases of Mediterranean fever, 569 (33%) have been diagnosed in Sicily and 333 (22%) in Sardinia. Nevertheless, these data are a likely underestimate because most cases are not reported to the relevant authorities and have been treated in the regional paediatric hospitals with a relatively higher risk of severe complications.
• The aim of our study was to retrospectively analyse the incidence as well as clinical and laboratory parameters of Rickettsioses cases causing MSF in children admitted to the Paediatric Operative Unit of the Policlinico-Vittorio Emanuele University Hospital, University of Catania, Italy, from 1987-2010.
• In our study we found an increasing incidence of Rickettsia infection causing MSF in children living in Catania, Sicily, Italy, from 1987 to 2010. This was associated with a concurrent change of antigenicity of R. conorii, with a higher expression of pathogenic antigens. The widespread incidence of pets living in domestic environments seems to be linked to a higher incidence of R. conorii infections.
• Therefore we want to stress the importance of our study in improving knowledge about this infectious disease, especially in its atypical forms, aiding the paediatrician considering a diagnosis of Rickettsia infection in cases presenting with fever and skin rash but without its typical Tache Noire, and encouraging the scientific population to diagnose those cases of Rickettsia infection to avoid further spread of the disease.

SummaryBackgroundZoonoses 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 methodsWe 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.ResultsWe 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).ConclusionsThese 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.