Cryptosporidiosis surveillance - United States, 2006-2008

Cryptosporidiosis is a nationally notifiable gastrointestinal illness caused by chlorine-tolerant protozoa of the genus Cryptosporidium.

2006-2008.

State and two metropolitan health departments voluntarily report cases of cryptosporidiosis through CDC's National Notifiable Diseases Surveillance System.

During 2006-2008, the number of reported cases of cryptosporidiosis increased dramatically (79.9%), from 6,479 for 2006 to 11,657 for 2007, and then decreased (9.9%) to 10,500 in 2008. All jurisdictions reported cryptosporidiosis cases during the reporting period, and the number of jurisdictions reporting >2.5 cases per 100,000 population increased from 20 in 2006 to 26 in 2007 and 27 in 2008. A greater number of case reports were received for children aged 1-9 years and for adults aged 25-39 years than were received for persons in other age groups. The number of cases reported among males and females was similar. Racial and ethnic comparisons were difficult because many case-reports did not report race and ethnicity. Peak onset of illness occurred annually during early summer through early fall.

Transmission of cryptosporidiosis occurs throughout the United States, with more frequent diagnosis or reporting occurring in northern states. An increase in cases reported for 2007 and 2008 is attributable partially to multiple large recreational water-associated outbreaks. State incidence figures should be compared with caution because individual state surveillance systems have varying capabilities to detect cases, and reporting might vary. The seasonal peak in age-specific case reports coincides with the summer recreational water season and likely reflects increased use of communal swimming venues (e.g., lakes, rivers, swimming pools, and water parks) by young children.

Local and state health departments can use cryptosporidiosis surveillance data to better understand the epidemiologic characteristics and the disease burden of cryptosporidiosis in the United States, design efforts to prevent the spread of disease, and establish research priorities.