Battling Cyclospora:

Unveiling the Emerging Pathogen’s Threat and Strategies for Containment


In the realm of infectious diseases, Cyclospora cayetanensis has emerged as a formidable adversary. Once a stranger in many regions, this microscopic parasite has now spread its wings far and wide, causing an infection known as cyclosporiasis. With its ability to wreak havoc through a range of debilitating symptoms, Cyclospora poses a significant public health challenge. In this article, we delve into the world of Cyclospora, exploring its impact, transmission, and offering proactive strategies to combat its spread. Cyclospora cayetanensis is a microscopic parasite that can cause a diarrheal illness called cyclosporiasis. This infection is becoming increasingly common in the United States, and it can be especially serious for vulnerable individuals, such as children and those with weakened immune systems.

Infected people shed unsporulated (non-infective; immature) Cyclospora cayetanensis oocysts in their stool; immature oocysts usually require at least 1–2 weeks under favourable laboratory conditions to sporulate and become infective. An unsporulated oocyst, with undifferentiated cytoplasm, is shown (far left), next to a sporulating oocyst that contains two immature sporocysts (A). An oocyst that was mechanically ruptured has released one of its two sporocysts (B). One free sporocyst is shown as well as two free sporozoites, the infective stage of the parasite (C). Oocysts (D) are auto-fluorescent when viewed under ultraviolet microscopy (E). (Credit: CDC/DPDx)

The Rise of Cyclospora

Cyclospora cayetanensis is a protozoan parasite responsible for cyclosporiasis, an infection that primarily affects the gastrointestinal system. While it was initially considered a rare occurrence in many parts of the world, Cyclospora has gained notoriety for its ability to thrive in various environments, leading to outbreaks in regions where it was once uncommon. The reasons behind its proliferation are multifaceted, including global travel, changing weather patterns, and contaminated food and water sources.

The Trouble with Cyclosporiasis

Cyclosporiasis is characterized by a range of distressing symptoms, which can include watery diarrhea, nausea, vomiting, abdominal cramps, bloating, and flu-like symptoms. Left untreated, the infection can persist for weeks to months, causing chronic discomfort and dehydration. Vulnerable populations, such as children and individuals with compromised immune systems, are at a higher risk of severe illness and complications. People can become infected with Cyclospora by eating or drinking contaminated food or water. The incubation period for cyclosporiasis is usually 7-10 days, but it can range from 2-14 days.

There is no vaccine or specific treatment for cyclosporiasis. However, it can be treated with antibiotics, such as trimethoprim/sulfamethoxazole. Treatment usually lasts for 7-10 days, but it may take longer for the symptoms to go away completely

Cyclospora life cycle

The life cycle of Cyclospora involves several stages and typically requires a host to complete its development. Here’s an overview of the Cyclospora life cycle:

Oocyst Stage:

The life cycle begins with the formation of oocysts, which are the infectious stage of Cyclospora. These oocysts are typically excreted in the feces of an infected individual. They are not immediately infectious upon excretion and require a period of time outside the host to become fully mature and capable of causing infection.


Oocysts released in the environment undergo a process called sporulation. During sporulation, the oocysts develop into a mature and infectious stage. This process usually occurs in a moist environment, such as in soil or water.


Once the oocysts have sporulated and matured, they become infectious to humans. Individuals can become infected with Cyclospora by consuming food or water that has been contaminated with sporulated oocysts.

Human Host:

Once ingested, the sporulated oocysts pass through the stomach and reach the small intestine, where they release sporozoites. These sporozoites invade the epithelial cells lining the intestine and develop into a form known as trophozoites.

Trophozoite Stage:

Trophozoites are the replicating stage of Cyclospora. They multiply within the host’s intestinal cells and can cause damage to the epithelial lining. This can lead to gastrointestinal symptoms such as diarrhoea, abdominal cramps, nausea, and vomiting.

Sexual Reproduction:

After several rounds of asexual replication as trophozoites, some of the trophozoites undergo sexual reproduction within the host’s intestinal cells. This results in the formation of new oocysts.

Oocyst Shedding:

The newly formed oocysts are then excreted in the host’s feces. These oocysts are not immediately infectious and need to undergo sporulation outside the host to become capable of causing infection in a new host.

It’s important to note that the precise details of the Cyclospora life cycle may vary depending on environmental conditions and the specific host species involved. Additionally, the life cycle can take around one to two weeks to complete.

Transmission and Risk Factors

Cyclospora infections are typically contracted by consuming food or water contaminated with sporulated oocysts, the infective form of the parasite. The oocysts can survive in the environment for an extended period, making contamination of water sources and fresh produce a major concern. Travellers to regions with poor sanitation and hygiene practices are also at risk, as they may inadvertently ingest contaminated food or water.

Cyclospora is spread through contaminated food and water. The parasite can survive for weeks in warm, moist environments, so it can be found in a variety of foods, including:

  • Fresh produce, such as raspberries, lettuce, and basil
  • Unpasteurized dairy products
  • Contaminated water

The symptoms of cyclosporiasis typically include:

  • Watery diarrhoea
  • Fatigue
  • Loss of appetite
  • Weight loss
  • Stomach cramps
  • Bloating
  • Nausea
  • Vomiting
  • Headache/ Fever

In some cases, cyclosporiasis can also cause more serious complications, such as kidney damage and inflammation of the heart, lungs, and liver.

Proactive Measures to Combat Cyclospora

To effectively manage the threat posed by Cyclospora, a multi-faceted approach is necessary:

  1. Improved Sanitation and Hygiene

Implementing stringent sanitation and hygiene practices in food production, processing, and preparation are crucial. This includes proper hand washing, safe water handling, and thorough cleaning of fruits and vegetables. 

  1. Enhanced Surveillance and Reporting

Developing robust surveillance systems to monitor outbreaks and track cases of cyclosporiasis is essential for early detection and swift response. Timely reporting can help prevent further spread. 

  1. Public Awareness and Education

Raising awareness about the risks of Cyclospora infection and disseminating information on preventive measures can empower individuals to protect themselves and their communities. 

  1. Safe Water and Food Supply

Ensuring access to clean and safe water sources and promoting responsible farming practices can significantly reduce the risk of contamination. 

  1. Medical Training and Resources

Equipping healthcare professionals with the knowledge and tools to diagnose and treat cyclosporiasis promptly is vital for reducing the severity of infections and preventing complications. 

  1. Travel Precautions

Travellers should be educated about the risks of consuming local foods and water in areas with inadequate sanitation. Precautionary measures such as using bottled water and avoiding raw produce can help minimize exposure. 

  1. Wash your hands often

This is the single most important thing you can do to prevent the spread of cyclosporiasis and other infections. Be sure to wash your hands with soap and water for at least 20 seconds, especially after using the bathroom, changing diapers, and before preparing or eating food. 

  1. Cook food thoroughly

Cyclospora can be killed by cooking food to the proper internal temperature. Be sure to cook poultry, meat, and fish to an internal temperature of 165 degrees Fahrenheit. Vegetables should be cooked until they are tender. 

  1. Avoid raw or undercooked vegetables

Cyclospora can be found in raw vegetables, especially leafy greens. If you are concerned about cyclosporiasis, it is best to avoid raw vegetables altogether or to cook them thoroughly. 

  1. Drink bottled or boiled water when travelling

If you are travelling to a region where cyclosporiasis is common, it is best to drink bottled or boiled water. Avoid drinking tap water, as it may be contaminated with cyclosporiasis. 

  1. Get tested if you have symptoms

If you develop symptoms of cyclosporiasis, such as watery diarrhea, fatigue, loss of appetite, and weight loss, it is important to see a doctor right away. Cyclosporiasis can be treated with antibiotics, but it is important to get treatment early to prevent complications. 

  1. Be proactive and vigilant

Cyclosporiasis is an emerging threat, but it is one that can be prevented. By following these tips, you can help protect yourself and your family from this infection.

Q & A:

  • What is cyclosporiasis? : It is an intestinal illness caused by a microscopic parasite.
  • How is it spread? : People can become infected by consuming food or water contaminated with feces (stool) that contains the parasite. Cyclospora is not spread directly from one person to another.
  • What should I do if I think I might have cyclosporiasis? : See your healthcare provider.
  • What can I do to prevent cyclosporiasis? : Avoid food or water that may have been contaminated with stool.
    When travelling, follow safe food and water habits
  • How is cyclosporiasis diagnosed? : By examining stool samples. Identifying Cyclospora in stool requires special lab tests that are not routinely done. Therefore, your healthcare provider should specifically request testing for this parasite. And more than one stool sample from different days might be needed. Your healthcare provider also might have your stool checked for other organisms that can cause similar symptoms.
  • How is cyclosporiasis treated in people with symptoms? : It usually is treated with the antibiotic trimethoprimsulfamethoxazole (also known as Bactrim*, Septra*, or Cotrim*). People with diarrhoea also should rest and drink plenty of fluids.


Cyclospora’s journey from being a stranger to a widespread and concerning pathogen highlights the dynamic nature of infectious diseases in today’s globalized world. As cyclosporiasis continues to challenge public health systems, proactive and vigilant measures are essential to curb its spread. By fostering collaboration among governments, healthcare institutions, and communities, we can effectively mitigate the impact of Cyclospora cayetanensis and safeguard the health and well-being of populations, especially those who are most vulnerable.

Ashutosh Jaiswal

Author is Head of Quality Assurance & Food Safety