Prevalence of antibodies to Bartonella henselae in patients with suspectedcat scratch disease (CSD) in Italy

Cat scratch disease (CSD) is a relatively new diagnosed illness with clinic al signs of self-limiting regional lymphadenopathy accompanied by symptoms of fever and malaise, to encephalopathy and neuropathy, occurring after a c at scratch or flea bite. Bartonella henselae is now accepted as the etiolog ic agent of CSD. From January 1994 to September 1998, 412 patients were eva luated for suspect CSD in Italy. Sera were tested for antibodies to B. hens elae by a commercially available indirect immunofluorescent assay (IFA), ba sed on B. henselae-infected Vero-cells as the antigen substrate. Of the 412 patients, 26 (6.3%) were considered positive having titers of immunoglobul in G (IgG) to B. henselae of 64 or higher. In these patients CSD was indeed confirmed by either histopathologic examination of lymph nodes biopsy or f ourfold raise in antibody titers. Nevertheless, sera were tested by IFA for Afipia felis and one showed a double reactivity to B. henselae and A. feli s. Finally, three sera, negative to B. henselae serology, were positive to A. felis. Three hundred and eighty-six patients received alternative diagno ses. One hundred and twenty-five serum samples from control subjects were n egative by IFA for either B. henselae or A. felis. Moreover, a cross-reacti vity with sera from patients affected by other diseases was not observed. O ur study shows that the ascertained cases of CSD are etiologically determin ed by B. henselae, IFA assay is confirmed as a useful tool in the laborator y diagnosis and, over a 5 years period of study, the incidence of CSD in It aly has been low.