The Centers for Disease Control and Prevention (CDC) has released its 2009 – 2010 surveillance summary for Cryptosporidium in the United States. The Cryptosporidium protozoa causes the gastrointestinal illness cryptosporidiosis. During the reporting period, fifty state and two metropolitan public health agencies (District of Columbia and New York City) reported cases of the disease through the CDC’s National Notifiable Diseases Surveillance System.
In 2009, 7,656 confirmed and probable cases were reported. That increased to 8,951 confirmed and probable cases in 2010. The cases were most frequently reported in children aged 1 to 9 years, followed by adults aged 25 to 29 years. The cryptosporidiosis rate in the Midwest was 1.3 to 2.9 times greater than other regions in 2009 and 1.8 to 4.6 times greater than other regions in 2010. The peak illness onset is in early summer through early fall, which coincide with the summer recreational water season. The increase in cases may reflect the increased use of swimming pools, water parks, and interactive fountains by young children.
Transmission is from fecal contamination in the water, by contact with infected animals, and by ingesting contaminated food. The infectious dose is very low. Swimmers can swallow water that contains the parasite or the oocyst, which is infectious immediately after excretion in feces. For instance, there was an outbreak of Cryptosporidium at two Minnesota water parks in April 2012.
The parasite is evolving, with multiple species that can infect human beings. C. hominis exists in a human-t0-human transmission cycle, while C. parvum infects humans and rumaninants (cows). Multiple subtypes of those species can infect humans.
Cryptosporidiosis is characterized by weight loss, abdominal pain, diarrhea, anorexia, fatigue, joint pain, headache, fever, and vomiting. Young children, pregnant women, and those with severely weakened immune systems can develop dehydration and other serious or life-threatening diseases.
The oocyst is very tolerant to chlorine, which means that swimmers must practice healthy behavior to control the spread of this disease. Do not swim if you have diarrhea and, if you are diagnosed with cryptosporidiosis, stay out of the water and avoid serving food to others for at least 2 weeks following recovery.