By: James Peacock

The outbreak of Cyclospora poisoning in Texas continues to be investigated by the Texas Department of State Health Services. The outbreak investigation was originally announced on July 17, when Texan health officials announced that there had been an uptick in reported cases of Cyclospora poisoning. At that point, there were 68 people sickened in the outbreak. The health department has continued to update the number of cases every Tuesday and Friday. As of August 1, there are now 160 cases of illness linked to this outbreak. For comparison’s sake, there were only 148 cases of Cyclospora poisoning reported in Texas for the entire year of 2016.

There have been 38 different counties affected by the outbreak. Harris County has been hit hardest by the outbreak, with 42 cases being reported. Bexar County has reported the next highest number of cases with 23. Tarrant County has reported 14 cases, Travis County has reported 10 cases, Dallas County reported 10 cases, Denton County reported seven cases, Fort Bend County has reported seven cases, Montgomery County has reported four cases of illness, Galveston County has reported three cases, and Williamson County has reported three cases. Collin County, Comal County, Coryell County, Hidalgo County, Kendall County, and Parker County have all reported two cases of illness. Bastrop County, Bell County, Brazoria County, Brazos County, Cameron County, Cooke County, Erath County, Freestone County, Guadalupe County, Hays County, Hood County, Johnson County, Kaufman County, Lavaca County, Maverick County, Midland County, Montague County, Palo Pinto County, Throckmorton County, Walker County, Washington County, and Wilson County have all reported one case each. Three cases of illness have not been attributed to any county as of yet.

Cyclospora outbreaks are commonly caused by outbreaks, with outbreaks being tied to salads, basil, raspberries, snow peas, contaminated water, and various lettuces. Cyclospora outbreaks are somewhat common and usually happen at a rate of two outbreaks per year. A source for each outbreak is discovered about half of the time. Most of these outbreaks average about 21 cases of illness. Recently, outbreaks of Cyclosporiasis have been repeatedly linked to cilantro from Mexico. So many illnesses were linked to imported cilantro that the FDA eventually filed an importation alert on cilantro from Puebla, Mexico. The FDA has updated and refined their alert over the years, especially after 2016, when the FDA reported that there was a noticeable drop in the number of Cyclospora cases after the alert was issued.

There has still not been any confirmation about the source of the current Cyclospora outbreak. The Texas Department of State Health Services is working with local health departments in an effort to track down more information about the outbreak. The process of investigating an outbreak usually involves the taking of samples and the conducting of interviews. There is sometimes a correlation between interview answers, which can help investigators find food or drink items common amongst affected individuals. These commonalities can aid in determining a source. Interviews can help locate potential sources, the best way for health officials to confirm information about an outbreak is through the testing of samples. When medical providers retrieve samples from ill people or from the environment, the samples undergo testing to learn more about them. This type of testing reveals is the bacteria’s DNA fingerprint. This fingerprint, a solution of the process of pulsed field gel electrophoresis (PFGE), is unique to the bacteria and strain involved in the outbreak. Health investigators will also run a test called whole genome sequencing (WGS). This test will record the entire DNA sequence of a pathogen and will provide a more detailed report on the pathogen than a PFGE. When multiple samples are shown to be closely related on a genetic scale, it is likely that they are a part of the same outbreak or contamination depending on when the sample was taken. By looking at clues like these, investigators can figure out what caused an outbreak and just how widespread the outbreak is.


Cyclospora are single celled protozoa that can be found in a variety of animals and environments. There are quite a few different types of Cyclospora, but only one species, Cyclospora cayetanensis, has been known to cause illness in humans. Immature oocysts are shed through fecal matter. It takes around one or two weeks outside of the body in order for the oocysts to mature. After this maturation process, Cyclospora protozoa can become infective. Not much is known about the number of protozoa required to cause a case of illness, but upon exposure to the protozoa, symptoms will appear between 7 and 10 days afterward. There is a wide variety of symptoms that can present with a Cyclospora infection including loss of appetite, weight loss, watery diarrhea, nausea, abdominal cramping, bloating, headache, fever, vomiting, and body aches. These symptoms can last up to months, although they may go away on their own within a few days. Cyclospora infections do present with the chance to cause a relapse, meaning that the illness may return even after symptoms originally subside. According to the CDC estimates from January of 2011, there have been no deaths attributed to Cyclospora infections. However, Cyclospora infections can still be fairly serious, and can even result in hospitalization being required. Anyone can get a Cyclospora infection, but children, the elderly, those with suppressed immune systems, and those living in tropical or subtropical areas are more likely to catch a Cyclospora infection. Cyclospora infections are much more common in the summer than in the winter. In the United States, the majority of Cyclospora infections take place between May and July.

Cyclospora Testing and Diagnosis

If you or a loved one begins to show the symptoms of a Cyclospora infection, it is a good idea to go see a doctor. Often, the doctor will recommend rest and hydration, but they will also probably run some tests to find the cause of the infection. Cyclospora is not necessarily tested for on every occasion, so if you believe that you have a Cyclospora infection–and are presenting the symptoms listed above–it is a good idea to suggest that your doctor run a Cyclospora test. This test involves a stool sample and will attempt to isolate Cyclospora oocysts. There are quite a few steps that are involved in sampling and testing for Cyclospora. For more information about the testing process, click here. If you test positive for a Cyclospora infection, the doctor will likely prescribe a round of antibiotics. The antibiotic Trimethoprim/sulfamethoxazole, usually sold under the names Bactrim, Septra, or Cotrim, is typically used to treat cases of Cyclosporiasis.