By: Heather Williams

Cyclospora cases are on the rise with New York City on the list as the next major city issuing a Health Alert.  Commissioner Mary T. Bassett, MD, MPH of the New York City Department of Health and Mental Hygiene has issued a Health Alert on July 24, 2017 for an “increase in Cyclospora diarrheal disease,” urging New York City clinicians to consider Cyclospora diagnostic testing for patients presenting unexplained watery diarrhea for more than 5 days.  Clinicians must specifically order a test for Cyclospora diagnostic testing, as this organism is not typically part of the routine panel.

According to the Health Alert, the New York City Health Department generally sees around 50 reported cases of Cyclospora infection per year.  Most cases occur in the Summer months, between June and September.  The city is on par to surpass the two previous years numbers. Between January 1, 2017 and June 30, 2017, the city had 27 reported Cyclospora cases.  This is a drastic increase from the 13 cases in 2016 and 21 cases in 2015 for that same time period.  While the presence of an “outbreak” has not yet been expressed, health officials are monitoring this unusual frequency of this pathogen.

The New York City Health Department is currently investigating to determine if there is a common source.  According to interviews, about half of those infected had traveled to places where Cyclospora is endemic around two weeks prior to illness onset.  Other options to consider is the implementation of a more sensitive diagnostic device, multiplex PCR, that may be able to identify more cases of the disease that may have been overlooked using other diagnostic methods.  Previous diagnostic methods consisted of identifying the cells in a stool sample.  Cyclospora oocyst spores are difficult to identify and the technician must have a keen eye or looking for those cells in particular.  Using wet mount microscopy is a reliable method for many bacterial identifications, but PCR is very reliable with a small number of cells.  Presence of that specific bacterial DNA provides a more sensitive way of identifying infection.  More samples may be confirmed now than in previous years using a different diagnostic method.

Key symptoms include watery diarrhea, loss of appetite, nausea, abdominal cramping, and fatigue.  Cyclospora is not transmitted directly from person to person, but from ingesting food or water contaminated with infectious feces.  While most cases Cyclospora throughout the world occur because they are endemic in those areas, instances in the United States are often linked to fresh produce.  Raspberries, lettuce, and cilantro are the primary sources.  No known source has been identified so far for those sickened in New York City.

Where is the Cyclospora Coming From?

The Cyclospora in this geological area could be linked to the current outbreak in Texas, or could be completely coincidental.  Looking at both the interviews in current cases and previous outbreak scenarios, epidemiologists will start to put the pieces together.

First, investigators will ask those with confirmed cases what they have done in the past few weeks.  What foods do the eat, places they shop, groups they interact with, etc. Hopefully, a common source comes from these interviews.  In many cases, most of those who are ill have eaten at a particular restaurant.  Perhaps they shop from stores who use the same distributor.  Maybe they have visited the same recent travel destinations.  Texas is also experiencing a Cyclospora outbreak with unknown source.  Investigators will likely reach out to identify if the two outbreaks are related.

Investigators will look at common sources of Cyclospora. In the United States, this is often contaminated produce.  Produce that is typically served raw is more susceptible than other foods where the parasite could be killed by cooking.  Lettuces, soft berries such as raspberries, blackberries, and strawberries, and herbs such as cilantro and basil have been responsible for Cyclospora outbreaks in the past.

Interviews in the current cases in New York City have found many of those affected have traveled outside of the United States within the last two weeks.  It is possible many of those cases came back already infected with the bacteria.  With immediate fecal matter being immediately non-contagious, it is unclear where the others who have not travel to those high-risk destinations came in contact with infectious fecal matter.  For this reason, travel locations may not be the actual source for all of those who are ill.

How to Stop the Life Cycle and Prevent Future Infections

Cyclospora infection occurs when a person ingests food or drinks that have been contaminated with fecal matter.  The person becomes ill and then infectious themselves.  The pathogen is eliminated in the feces of the infected person in spore form.  With the pathogen being sporulated, typical diagnostic methods are often ineffective.  Additionally, in the spore form, the pathogen is not infectious.  After the oocytes come out of their spore phase within a few weeks, any food or water supply can become contaminated.  The next host somehow consumes the infectious feces and the cycle starts all over again.

Understanding how Cyclospora infection is transmitted, a person can take control of the life cycle and successfully avoid becoming infected.

  • Use caution when traveling to areas where Cyclospora are endemic. In some tropical locations, the bacteria live in the environment and transmission is at a much higher rate than in other parts of the world.  Refer to the CDC’s travel notices page for updated information on risks associated with your destination.
  • Use a clean water source. Most public water supply is safe for consumption.  Always pay attention for advisories to boil water in the event of known contamination from the water source.  Water from rivers, lakes, and streams should be treated with an appropriate sterilization method.  When traveling to higher risk areas
  • Always wash fresh produce with clean water thoroughly before consuming. Produce consumed fresh is not killed by heat, so bacteria may be present on the surface from growing near an infected water source. Be sure to use safe, clean water to clean produce.
  • Protect yourself by washing your hands prior to preparing, serving, and/or eating food. This will help reduce the spread of infection if you have come in contact with the bacteria in daily contact.