Cyclospora cases reach 843 in US as officials seek outbreak source

A cyclospora outbreak has reached at least 843 confirmed cases and 86 hospitalizations in the United States, according to the Centers for Disease Control and Prevention, with no common source yet identified. The uncertainty has left restaurants, grocers and agricultural suppliers awaiting guidance, although stocks across those sectors were largely steady on Monday.

The CDC figures, current as of July 9, may understate the scale of the outbreak because state health departments report cases to the federal agency with a delay. State officials have reported above-average case counts in geographically dispersed places including Michigan, New York, Kentucky and Texas.

Cyclospora is a parasite that can spread through contaminated food or water. The illness it causes, cyclosporiasis, is commonly associated with watery diarrhea that can last for weeks, according to the CDC. Other symptoms cited by the agency include weight loss and loss of appetite.

The outbreak has not been connected to a single product, supplier or location. That matters for food-related businesses because public health investigations often determine whether recalls, menu changes or supply-chain checks are needed. Without an identified source, companies have limited information on what operational steps, if any, are warranted.

Spokespeople for several restaurant companies told CNBC they were aware of the outbreak but had not seen evidence that their ingredients were at risk. Those companies included Chipotle Mexican Grill and Restaurant Brands International, the parent company of Burger King, Popeyes, Tim Hortons and Firehouse Subs.

What health officials know

The CDC describes cyclospora as an infection that is rarely fatal. Dianna Blau, acting chief of the CDC’s parasitic diseases branch, told the Associated Press on July 9 that there was no evidence the parasite had changed in a way that made it more infectious.

Past cyclospora outbreaks have often been associated with fresh produce. The foods cited in prior outbreaks include raspberries, basil, cilantro and lettuce. Federal and state investigators have not linked the current spread to any of those items or to any other common source.

Food-borne illness investigations typically rely on case reports, interviews with patients and supply-chain tracing. In this case, the CDC’s surveillance depends partly on reports from health providers and state agencies, which is why the confirmed national count can lag the actual number of infections.

CDC guidance for consumers

The CDC advises consumers to wash fresh produce before eating it and to wash their hands before handling or preparing food. Those steps reduce risk for a range of food-borne illnesses, although they do not identify the source of the current cyclospora cases.

For people with symptoms such as watery diarrhea, weight loss or loss of appetite, the CDC recommends contacting a primary healthcare provider rather than relying on at-home remedies. Clinicians can prescribe appropriate treatment, and confirmed diagnoses help public health authorities track the outbreak.

The economic impact remains unclear while the source is unknown. For now, the market reaction has been muted, and the public health investigation remains the central variable for companies exposed to fresh produce, prepared food and consumer dining demand.

This story draws on original reporting from CNBC.