Serological evidence of Cryptosporidium infections in southern Europe

Although cryptosporidiosis outbreaks have been frequently reported in the U nited States, Canada and the United Kingdom, few outbreaks have been report ed on the European continent. The reasons for this are unclear. To ascertai n whether a European population has been previously exposed to Cryptosporid ium, we conducted a survey of 100 resident blood donors in a northern Itali an city for IgG serological response to two oocyst antigen groups. A serolo gical response to the 15/17-kDa antigen group was detected in 83% of blood donors and response to the 27-kDa antigen group in 62%. Donors who traveled outside of Italy during the prior 12 months were less likely to have had a response to the 15/17-kDa antigen group (p < 0.04) and to have a less inte nse response (p < 0.05). Older age was predictive of a more intense respons e to each antigen group (p < 0.01). The fraction of Italian blood donors wi th a serological response to either antigen group was higher than in four U nited States blood donor populations, with differences more pronounced for response to the 15/17-kDa antigen group (p < 0.01). A lower fraction of Ita lian donors had a serological response to either antigen group than persons tested at the time of a cryptosporidiosis outbreak in the United States or blood donors tested six months after that outbreak (p < 0.05). Since the p resence of serological responses to these antigen groups predicts a reduced risk of cryptosporidiosis, the high prevalence of serological responses in these Italian blood donors may explain the infrequent occurrences of clini cally detectable cryptosporidiosis in this city.