The US Centers for Disease Control and Prevention (CDC), state and local health departments, and the US Food and Drug Administration have issued a Health Alert Network advisory after an increase in reported cases of cyclosporiasis, an intestinal illness caused by the parasite Cyclospora cayetanensis.
According to the alert, clinicians should consider a diagnosis of cyclosporiasis in patients who experience prolonged or remitting-relapsing diarrhea.
Since May 1 of this year, 206 cases have occurred, more than twice the 88 cases reported from May 1 to August 3, 2016.
The reports have come from 27 states, but it's unclear whether those cases are related; 18 patients required hospitalization, but no deaths have been reported. The alert says it's too early to point to a source of contamination.
Most laboratories in the United States do not routinely test for Cyclospora, even when a stool sample has been tested for parasites, so providers must specifically order the test.
"Several stool specimens may be required because Cyclospora oocysts may be shed intermittently and at low levels, even in persons with profuse diarrhea," the report states.
Any suspected or confirmed cases should be reported to public health authorities, the CDC says.
The most common symptom is watery diarrhea, which can be profuse. Other common symptoms include anorexia, fatigue, weight loss, nausea, flatulence, stomach cramps, myalgia, vomiting, and low-grade fever.
On average, symptoms begin 7 days after ingestion of the parasite, but symptoms can begin from 2 days to more than 2 weeks after ingestion.
Infection with Cyclospora can occur following consumption of contaminated food or water. Cyclospora is not transmitted directly from person to person.
The recommended treatment is trimethoprim/sulfamethoxazole (TMP/SMX). There are no effective alternatives for people who are allergic to or who cannot tolerate TMP/SMX; observation and symptomatic care is recommended for those patients. If untreated, illness may last for a few days to a month or longer.
Previous outbreaks in the United States have been linked to imported produce, but no link to produce has been reported this year.
Cyclospora was among reported causes of foodborne illness in 2016. The latest FoodNet report shows that Campylobacter (8547) and Salmonella (8172) were the leading causes of such infections last year, followed by Shigella (2913), Shiga toxin–producing Escherichia coli (1845), and Cryptosporidium (1816). For comparison, about 300 or fewer cases each of Yersinia, Vibrio, Listeria, and Cyclospora infection were also reported.