Problem/condition: Cryptosporidiosis is a nationally notifiable gastrointestinal illness caused by extremely chlorine-tolerant protozoa of the genus Cryptosporidium.
Reporting period: 2009-2010.
System description: Fifty state and two metropolitan public health agencies voluntarily report cases of cryptosporidiosis through CDC's National Notifiable Diseases Surveillance System.
Results: For 2009, 7,656 confirmed and probable cases of cryptosporidiosis (2.5 per 100,000 population) were reported; for 2010, 8,951 confirmed and probable cases (2.9 per 100,000 population) were reported. All jurisdictions reported cryptosporidiosis cases for 2009-2010, and the number of jurisdictions reporting >3.5 cases per 100,000 population was 18 for 2009 and 20 for 2010. Cases were most frequently reported in children aged 1-9 years, followed by adults aged 25-29 years. This is the first reporting period in which more cases of cryptosporidiosis were reported in females than in males. Peak onset of illness occurred during early summer through early fall; the sympton onset of cases in children aged 5-9 years peaked earlier than that of cases reported in adults aged 25-34 years.
Interpretation: Transmission of Cryptosporidium occurs throughout the United States. Rate data from reporting jurisdictions should be compared with caution because individual jurisdictions have varying capacities to detect, investigate, and report cases. The symptom onset and age-specific peaks coincide with the summer recreational water season and might reflect increased use of communal swimming venues (e.g., swimming pools and interactive fountains) by young children who then transmit the parasite to other users and their caregivers.
Public health action: Local, state, and federal public health agencies can use cryptosporidiosis surveillance data to characterize the epidemiology of cryptosporidiosis in the United States, establish public health priorities (e.g., research) to improve cryptosporidiosis prevention and control, and design and evaluate efforts (e.g., health communication and policy) to prevent and control the transmission of Cryptosporidium.