Fresh produce used to make salads has always been a cornerstone of healthy meals. Eating raw salads can offer better hydration and availability of heat-sensitive vitamins, but occasionally these fresh fruits and vegetables can become the carriers of invisible parasites.
Cyclospora cayetanensis is a cyst-forming coccidian protozoan that causes a severe gastro-enteric diarrheal disease called cyclosporiasis. Although there are about 19 identified species of Cyclospora, C. cayetanensis is commonly associated with acute and chronic diarrhoea in humans. In addition to being highly resistant to the disinfectants commonly used in the food industry, globalization and export of food products have also increased its geographical spread.
Cyclospora is transmitted via the faecal-oral route. Unsporulated oocysts are shed in the faeces of infected individuals, contaminating soil and water sources. These oocysts require a period of sporulation in the environment to become infectious. This makes human-to-human transmission unlikely. Infection occurs following the ingestion of sporulated oocysts in contaminated food or water. After an incubation period of 1 to 11 days, patients typically present with abdominal cramps, watery diarrhoea, fatigue, anorexia and low-grade fever. Although Cyclospora cayetanensis can infect individuals of all ages, children, older adults, and immunocompromised individuals are at greater risk of developing severe and prolonged disease.
Laboratory diagnosis can be made by observing oocysts isolated from the wet mount of the patient’s faecal sample under the light microscope. Modified acid-fast staining can be used to detect Cyclospora oocysts. Because infected individuals may shed only small numbers of oocysts, multiple stool specimens collected over several days are often required to establish the diagnosis. Moreover, Cyclospora is not routinely included in many gastrointestinal multiplex PCR panels, increasing the likelihood of missed diagnoses.
Cyclosporiasis outbreaks have been reported in countries such as the US, Canada and Australia since 1995. They were primarily linked to the consumption of fresh produce such as raspberries, cilantro, lettuce, and bagged mixed salads. A multistate outbreak of cyclosporiasis is currently ongoing in the United States. According to the Centers for Disease Control and Prevention (CDC), 1,645 confirmed cases have been reported, of which 141 required hospitalizations. However, the true burden of the disease is likely to be substantially higher due to the underdiagnosis and underreporting of cyclosporiasis, particularly among individuals with self-limiting illness.
Published reports of cyclosporiasis in India are limited and have largely been confined to immunocompromised populations, particularly post-transplant recipients. Reports involving immunocompetent individuals are comparatively rare.
The mainstay treatment for C. cayetanensis infection is an antibiotic called trimethoprim–sulfamethoxazole (TMP–SMX: 160 mg trimethoprim, 800 mg sulfamethoxazole) twice daily for 7–10 days. This reduces the duration and the rates of recurrence of the disease. Ciprofloxacin is not as effective but can be used in patients with sulphonamide intolerance.
Hygiene practices such as cleaning hands well with soap and water pre- and post-handling of raw produce, rinsing fruits and vegetables using clean running water before consuming, and removing their outer layer and cooking/freezing whenever possible can reduce the chances of contracting cyclosporiasis. Prompt medical consultation may facilitate early diagnosis and treatment, which can significantly improve clinical outcomes in individuals with cyclosporiasis.
Dr Sowmya Sridharan
Consultant, Infectious Disease and Infection Control
Kauvery Hospital, Chennai
Dr. Deepti Nirja
Physician Associate, Department of Infectious Diseases
Kauvery Hospital, Chennai
