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CDC Works to Improve Cryptosporidium Tracking in the United States

In the United States, the parasite Cryptosporidium sickens almost 750,000 people each year with watery diarrhea that can last for weeks. Many of these illnesses are linked to swallowing contaminated water, such as water in swimming pools, because the parasite is not easily killed by chlorine. Illnesses can also be linked to eating contaminated food or coming in contact with an infected person or animal. State health departments track these illnesses by collecting information on the people who get sick.

Cryptosporidium used to be thought of as one species, but it is now known to be a family of species with many different subtypes. Some of these subtypes infect people. Being able to identify them will help public health professionals understand how the parasite is being spread and how to stop infections in the future, but Cryptosporidium species and subtypes all look the same when using traditional tests, like looking under the microscope. That’s why CDC scientists use DNA fingerprinting tests that identify the parasite’s species and subtype through its genes. However, even these DNA fingerprinting tests cannot distinguish between some of the most common subtypes. CDC must develop advanced DNA fingerprinting methods – with even more precise test results – to make this possible.

In 2010, CDC launched CryptoNet to collect Cryptosporidium DNA fingerprinting results. CryptoNet is the first tracking and DNA fingerprinting system for a disease caused by a parasite. It has provided valuable information on the different Cryptosporidium species infecting people in the United States. However, as the number of common Cryptosporidium species being entered into CryptoNet began to grow, state and federal scientists realized they needed a new, even more precise test. They also saw an opportunity to combine new, more detailed DNA fingerprinting information with tracking information about the people who got sick. This would help provide a clearer picture of how Cryptosporidium is spreading and help identify any new subtypes that come into the United States and start to spread.

Next Steps for CryptoNet

CDC will upgrade the current CryptoNet tracking system and fingerprinting methods to combine the information collected about people who got sick from the parasite with the DNA fingerprinting data. CDC also will develop new tests using whole genome sequencing to better distinguish all subtypes of Cryptosporidium. CDC will merge CryptoNet into PulseNet, CDC’s bacterial disease fingerprinting system. CDC scientists will work with the Minnesota Department of Health and others to look at all of Cryptosporidium’s DNA in samples from infected animals and humans, as well as in water and other environmental samples. Scientists will use these data as the basis for a new tracking system that will consistently distinguish which subtypes of Cryptosporidium are infecting people and animals in different parts of the country.

This new information will help health officials:

  • Detect and respond to outbreaks;
  • Learn more about how Cryptosporidium is spreading in the United States;
  • Identify new subtypes spreading in the United States; and
  • Develop more effective ways to prevent people from getting sick.
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