When Paradise Strikes Back: The Curious Story of Cyclospora

Cyclospora is in the news, causing explosive travelers' diarrhea throughout the United States and reportedly linked to lettuce served at Taco Bell. (1)  What most people don't know is that this outbreak traces back to a discovery story that was almost missed entirely - one that began in a quiet clinic in Kathmandu.

It was 1989. I had arrived in Kathmandu on a Fulbright scholarship to study the many causes of travelers' diarrhea (TD) in Nepal. Not a sexy topic, I know. Sadly, Nepal in the 80s and 90s was known in travel circles for two things: its beautiful mountains and its unsightly bathrooms. It was simply the cost of seeing Mt. Everest at the time. In fact, Nepal was the world headquarters for this prized TD distinction. The Fulbright foundation was keen on getting to the bottom of this issue - pun intended.

I was immediately taken in by physicians and friends at the Tribhuvan University Teaching Hospital (TUTH) and at the private CIWEC clinic run by Dr. David Shlim. I was introduced to David's laboratory technician, Rama—a quiet, hard-working perfectionist. The perfect protagonist for this curious story.

Rama, a methodical scientist, was the one person in Nepal you wanted analyzing your stool sample in 1989. A devout Bahá'í, Rama was serious about what he did, and he was the best in the world at it. Every stool sample mattered to Rama. As opposed to the generic analyses available on the streets of Thamel - the kind that positively listed every possible parasite, protozoa, or bacteria imaginable on your lab sheet - Rama's analyses were spot-on accurate. His reputation had spread to every consulate in Nepal, and they all fell in line to seek consultation from this stool master.

Rama utilized a variety of techniques on each stool sample to provide a comprehensive analysis of the pungent specimens before him. It was not long after my arrival that he told me about an organism he was seeing on a special sucrose flotation assay. Rama was looking for Cryptosporidium, but this bug looked different. It was twice the size of Crypto, and it appeared to be increasingly common - but only seasonally, in the summer months.

Bacterial pathogens account for approximately half of the cases of TD in Nepal with the main culprit being the local E. coli which envelops the market produce. The other endemic causes vary and include viruses, protozoa (like Entamoeba, Giardia & Cryptosporidium), and parasites like intestinal roundworms and flatworms. (2) What Rama found was different, and he knew it.

As with most great discoveries, it took more than one attempt to convince the powers that be that something was going on. When Rama finally yelled loud enough (and Rama never yelled), David listened. He was then able to link this new laboratory finding with a clinical illness that curiously was not improving with standard TD medications. David and Rama ultimately published their findings in a groundbreaking article and the CDC swarmed in from Atlanta to dig deeper. Initially believed to be blue-green algae (a cyanobacterium), Cyclospora was ultimately identified as a protozoa. (3)

Cyclosporiasis is now a well-documented cause of explosive diarrhea, cramping, and flu-like symptoms worldwide. It is spread through contaminated food and water, and assumed to be brought into the USA from foreign travel. It is now included in the Stanford Gastroenteritis PCR panel and can be treated with Bactrim, though symptoms are usually self-limited, and so many cases go undiagnosed.

Nearly 4 decades after Rama first spotted something strange under his microscope in Kathmandu, Cyclospora is back in headlines - this time not from a trekker’s stool sample but from a Kalamazoo Taco Bell. Paradise, it turns out, has a long reach.

References

1. Jewett, C., Callahan, A., & Legaspi, C. H. (2026, July 17). Cyclospora linked to Taylor Farms lettuce sent to Taco Bell. The New York Times. https://www.nytimes.com

2. Gianotti, A. J. (1990). Intestinal parasites of Nepal. Journal of the Nepal Medical Association, 28, 242–247.

3. Shlim, D. R., Cohen, M. T., Eaton, M., Rajah, R., Long, E. G., & Ungar, B. L. (1991). An alga-like organism associated with an outbreak of prolonged diarrhea among foreigners in Nepal. American Journal of Tropical Medicine and Hygiene, 45(3), 383–389.

Alan Gianotti is a concierge primary care physician at Crescendo MD in Portola Valley, California. He holds degrees in Microbiology (BS), Biology (MS) and is a Fulbright Scholar (Nepal) where he fostered a lifelong interest in infectious disease, travel and preventative medicine.