What is Cryptosporidium?

Cryptosporidium is a genus of apicomplexan protozoans that can cause a diarrheal disease called cryptosporidiosis. These microscopic parasites are encased within an outer shell, or oocyst, which allows them to survive outside a host for long periods and makes them resistant to common disinfectants like chlorine. When ingested, the oocysts travel to the small intestine where they release sporozoites that infect the epithelial cells, leading to cryptosporidiosis.

Cryptosporidium primarily spreads through contaminated water, but foodborne transmission is also a significant concern. There are several species of Cryptosporidium that infect humans, with Cryptosporidium hominis and Cryptosporidium parvum being the most common.

What Foods Can Be Contaminated?

Cryptosporidium can contaminate a wide range of food products, particularly those that come in contact with contaminated water or fecal matter. Here are some of the foods most commonly associated with Cryptosporidium contamination:

  • Uncooked Fresh Produce: Cryptosporidium can contaminate fresh produce such as salads, fruits, and vegetables if they are washed or irrigated with contaminated water.
  • Raw Milk and Dairy Products: These can become contaminated if the animal has cryptosporidiosis or if the milk is mixed with contaminated water.
  • Raw or Undercooked Meats: Meat from animals infected with Cryptosporidium can carry the parasite, especially if the meat comes in contact with fecal matter during processing.
  • Shellfish: Shellfish harvested from contaminated waters can be a source of Cryptosporidium.

Cryptosporidium oocysts are hardy and can survive on the surface of foods for long periods. Their resilience, combined with their small size, makes preventing contamination particularly challenging.

How Does it Affect Human Health?

Ingestion of Cryptosporidium oocysts can lead to cryptosporidiosis, an intestinal disease. The severity and duration of the illness can vary widely among individuals based on their immune status.


The symptoms of cryptosporidiosis may appear within 2 to 10 days after exposure, and can include:

  • Watery diarrhea
  • Stomach cramps or pain
  • Dehydration
  • Nausea
  • Vomiting
  • Fever
  • Weight loss

At-Risk Populations

Certain populations are more at risk for severe or prolonged illness:

  • Young Children: Their immune systems are not fully developed, making them more susceptible to infection and severe symptoms.
  • Elderly Individuals: The elderly may have weakened immune systems and are thus more susceptible to severe infections.
  • Immunocompromised Individuals: People with weakened immune systems due to conditions like HIV/AIDS, cancer, or organ transplants are particularly at risk.


In severe cases, cryptosporidiosis can cause life-threatening complications, especially in immunocompromised individuals. Prolonged or severe diarrhea can lead to dehydration, malnutrition, and weight loss.

Cryptosporidium infections have also been associated with the development of Irritable Bowel Syndrome (IBS) and other chronic gastrointestinal disorders in some individuals.

How Common is Illness?

Cryptosporidiosis is a significant global public health concern, particularly in low-resource settings with inadequate water sanitation. The disease incidence can be quite high during rainy seasons or in the aftermath of natural disasters when water supplies may become contaminated.


In developed countries, the reported incidence of Cryptosporidium infection has been on the rise. For instance, in the United States, the Centers for Disease Control and Prevention (CDC) recorded a 13% increase in cryptosporidiosis cases each year from 2009 to 2017. Such infections are also common in Europe, Australia, and other developed regions.


Outbreaks of cryptosporidiosis have been associated with recreational water facilities, child care settings, and contaminated food products. Foodborne outbreaks, though less common than waterborne outbreaks, can result in significant numbers of illnesses due to the widespread distribution of contaminated food products.


Regular surveillance and reporting of Cryptosporidium infections help in understanding its prevalence and in forming strategies to control its spread. Various countries have established surveillance systems to monitor and respond to Cryptosporidium outbreaks.

Where Does It Come From?

Cryptosporidium is primarily associated with fecal matter from both humans and animals. The parasites are shed in the stool of infected individuals or animals in the form of oocysts, which can then contaminate food, water, and the environment. Here are some common sources:

Animal Reservoirs

  • Livestock: Animals such as cattle, sheep, and goats can be significant reservoirs of Cryptosporidium, especially the species Cryptosporidium parvum.
  • Wildlife: Wild animals can also harbor Cryptosporidium and contaminate water sources.

Human Reservoirs

  • Infected Individuals: Humans infected with Cryptosporidium, particularly young children, can shed millions of oocysts daily during an infection.

Environmental Sources

  • Water: Water sources can become contaminated with Cryptosporidium from agricultural runoff, sewage overflow, and improperly treated wastewater.
  • Soil: Soil contaminated with fecal matter can harbor Cryptosporidium, which can then be transferred to food crops.

Food Processing and Handling

  • Cross-contamination: During food processing and handling, cross-contamination can occur from contaminated water, equipment, or the hands of food handlers.

Understanding the sources of Cryptosporidium is crucial for devising effective strategies to prevent and control its spread within the food chain.

How Is It Affected By Environmental Factors?

The environmental persistence of Cryptosporidium largely contributes to its transmission. The oocysts can survive for long periods in the environment, awaiting ingestion by a new host. Various environmental factors can affect the survival and transmission of Cryptosporidium:


  • Cold Temperatures: Cryptosporidium oocysts are more likely to survive in colder temperatures, which can extend their viability in water and on food surfaces.


  • Water: Cryptosporidium thrives in moist environments and can remain infectious in water for months.


  • Resistance to Chlorine: Unlike many other microorganisms, Cryptosporidium oocysts are highly resistant to chlorine disinfection, which is a common method used to treat drinking water and recreational water.

Soil and Organic Matter

  • Protection by Organic Matter: Organic matter can provide a protective environment for Cryptosporidium oocysts, shielding them from desiccation and UV radiation.

UV Radiation

  • Susceptibility to UV: Cryptosporidium oocysts are susceptible to inactivation by ultraviolet (UV) light, making UV disinfection a potential method for controlling Cryptosporidium in water.

Understanding these environmental interactions helps in devising strategies to control Cryptosporidium transmission, particularly in the context of food safety and water treatment.

How Can It Be Controlled?

Controlling the spread of Cryptosporidium requires a multi-faceted approach given its resilience and the various ways it can be transmitted. Here are some measures that can help in controlling Cryptosporidium particularly in the context of food safety:

Prevention at Source

  • Proper Animal Husbandry: Practices such as rotational grazing and regular veterinary care can help manage Cryptosporidium at the source.
  • Wastewater Treatment: Ensuring effective wastewater treatment can help reduce Cryptosporidium contamination in water sources.

Food Processing and Handling

  • Good Agricultural Practices (GAPs): Implementing GAPs can help prevent contamination of fresh produce.
  • Good Manufacturing Practices (GMPs): Adhering to GMPs can prevent cross-contamination during food processing.

Water Treatment

  • Ultraviolet (UV) Disinfection: As Cryptosporidium is sensitive to UV light, UV disinfection can be an effective measure.
  • Filtration: Physical removal of Cryptosporidium oocysts from water through filtration is another effective control measure.

Public Education

  • Awareness: Educating the public about the risks of Cryptosporidium and promoting personal hygiene can help prevent person-to-person transmission.

Surveillance and Monitoring

  • Regular Testing: Testing water and food products for the presence of Cryptosporidium can help identify and control outbreaks.


  • Continuous Research: Ongoing research to understand Cryptosporidium better and to develop new control measures is crucial for long-term management.

Implementing a combination of these measures can significantly contribute to reducing the risk of Cryptosporidium contamination and ensuring food safety.

Are There Rules and Regulations?

Numerous countries and international bodies have established rules and regulations to manage and mitigate the risks posed by Cryptosporidium, particularly in water and food supplies. Some of the key regulatory frameworks include:

United States

  • Safe Drinking Water Act (SDWA): Under the SDWA, the Environmental Protection Agency (EPA) has set standards for the reduction of Cryptosporidium in drinking water.
  • Food Safety Modernization Act (FSMA): The FSMA emphasizes preventing food contamination, including by pathogens like Cryptosporidium, through rigorous food safety plans.

European Union

  • Drinking Water Directive: The EU’s Drinking Water Directive sets standards for Cryptosporidium monitoring and reduction in drinking water.
  • Food Hygiene Regulations: EU’s food hygiene regulations require food businesses to implement procedures to manage food safety risks, including those posed by Cryptosporidium.

World Health Organization (WHO)

  • Guidelines for Drinking-water Quality: The WHO guidelines include recommendations for the management of Cryptosporidium in drinking water.

Codex Alimentarius

  • Codex Guidelines on Food Hygiene: The Codex Alimentarius, managed by the FAO and WHO, provides guidelines on food hygiene to prevent contamination, including by Cryptosporidium.

Other Regional and National Regulations

Various other countries have their own regulations and guidelines regarding Cryptosporidium control in water and food supplies.

These regulatory frameworks aim to provide a structured approach to managing Cryptosporidium risks, promoting public health, and ensuring food and water safety. The effectiveness of these regulations can be enhanced through continuous monitoring, research, and international cooperation to address the global challenge posed by Cryptosporidium.

References and Further Readings

Prevention & Control – General Public | Cryptosporidium | Parasites | CDC – This resource provides comprehensive information on the prevention and control of Cryptosporidium for the general public, hosted on the Centers for Disease Control and Prevention (CDC) website.

Foodborne cryptosporidiosis – PubMed – This article discusses the aspect of foodborne cryptosporidiosis, which is authored by researchers from various institutions including the Centers for Disease Control and Prevention.

Cryptosporidium | Institute of Food Science and Technology – This resource from the Institute of Food Science and Technology discusses Cryptosporidium outbreaks in the UK and measures for water treatment to prevent contamination in food.

Cryptosporidiosis: guidance, data and analysis – GOV.UK – This resource from the UK government provides guidance, data, and analysis on Cryptosporidiosis, which is beneficial for understanding regulatory and public health perspectives on managing Cryptosporidium​.

Cryptosporidiosis Control Guideline by NSW Health – This guideline by NSW Health serves as a control manual for public health units in managing Cryptosporidiosis cases, focusing on rapid response, case and contact management, environmental evaluation, and handling special situations like outbreaks in childcare facilities or swimming pools. It also emphasizes education on hygiene practices to prevent transmission.