ABSTRACT
Seroepidemiological studies of particular areas have indicated that the percentage of the population affected at some time in life can vary from under 20% to over 90%. Surveillance provides the foundation for understanding the epidemiology of cryptosporidiosis. Good laboratory detection coupled with timely reporting and regional or national analysis and reporting are essential for detecting all but the largest of outbreaks. The occasional occurrence of Cryptosporidium hominis in cattle and goats means that careful comparisons of human and animal strains are required to elucidate the epidemiology of human cryptosporidiosis. Two types of immunity have a bearing on the epidemiology of cryptosporidiosis. The first is the immune response to infection that results in resolution of infection within a week or two. The second is the sustained impact of prior infection on reexposure to oocysts. The strains involved in human disease appear to differ in their epidemiological characteristics.
