The number of people in Texas with infections from Cyclospora parasites has more than doubled since mid-July, causing state officials to renew requests for the public and health care providers to watch for symptoms — and report cases.

Often associated with fresh produce, the microscopic parasite has caused infections in 160 people as of Tuesday, up from the 68 confirmed cases initially reported by the Texas Department of State Health Services on July 17.

To view a larger version of the map, please click on the image.

“Disease investigators are busy gathering information about the current illnesses as they attempt to determine whether there is a common source for the current outbreak,” according to the outbreak update this week.

Victims are spread across at least 38 Texas counties, with highest case counts in Harris County with 42, Bexar County with 23, and Tarrant County with 14.

When the state posted its alert on July 17, it reported the 68 cases “within the past month.” Another 92 cases have been reported since then. It can take from two days to two weeks for symptoms to develop after exposure.

“The main symptom is watery diarrhea lasting a few days to a few months,” according to the Texas health department.

“Additional symptoms may include loss of appetite, fatigue, weight loss, abdominal cramps, bloating, increased gas, nausea, vomiting and a low fever. Symptoms may come and go multiple times over a period of weeks or months.”

Some people who are infected may not have any symptoms, but the infection is generally not spread via person-to-person contact, the state reported. Most infections from the parasite are from contaminated water or food. Cooking can kill the parasite, but routine chemical disinfection and sanitizing methods are unlikely to kill Cyclospora, according to the federal Centers for Disease Control and Prevention.

“Past outbreaks in the U.S. have been associated with consumption of imported fresh produce, including fresh pre-packaged salad mix, raspberries, basil, snow peas, and mesclun greens. Texas has had multiple outbreaks linked to cilantro,” according to the July 17 alert posted by the state health department.

“(The department) recommends thoroughly washing all fresh produce, but that may not entirely eliminate the risk because Cyclospora can be very difficult to wash off.”

Infections spike despite preventive measures
The number of people in the United States infected from Cyclospora parasites has been peaking annually in June and July for several years, with the vast majority of illnesses from May through August.

Because of multiple outbreaks traced to fresh cilantro from the region of Pueblo, Mexico, the U.S. Food and Drug Administration stepped up inspection and enforcement there.

“Beginning in 2015, from April 1 through August 31, cilantro from this region has been and continues to be detained without physical examination at the U.S.-Mexican border and refused admission into the United States,” according to the FDA.

“The April through August time period aligns with the seasonality of previous (Cyclospora) outbreaks. Only cilantro producers on the Green List in the state of Puebla, who must comply with 11 minimal requirements on good agricultural and food safety practices as part of Mexico’s Systems of Risk Reduction of Contamination, are excluded from detention without physical examination under the import alert.”

The Texas case count for 2016 — 148 reported Cyclospora infections — was an improvement on the previous three years. Texas reported 351 cases of cyclosporiasis in 2013; 200 in 2014; and 316 in 2015.

The FDA suggested in September 2016 that the lower number of infections that year correlated with the first full season that FDA’s Import Alert for fresh cilantro from Puebla was in effect.

Texas officials reported this week that they are working with local health departments in the search for the source of the infections this year. They stressed the importance of the cooperation of the public and health care providers.

The state health department urges people to seek medical treatment and providers to test them for Cyclospora if they have symptoms of infection.

“People with symptoms that could be related to Cyclospora should contact their health care provider for treatment,” according to the Texas health alert.

“(Providers should) test patients who have diarrhea lasting more than a few days or diarrhea accompanied by severe loss of appetite or fatigue. Health care providers should promptly report cases so that public health can investigate them and attempt to determine the source in order to head off future cases.”

(To sign up for a free subscription to Food Safety News, click here.)