In a Monday update on the nationwide Cyclospora outbreak from the U.S. Centers for Disease Control and Prevention (CDC), the agency stated that not all of the more than 600 current cases reported in 22 states and New York City are directly related to each other. Many of the recent cases have been reported from Texas, so CDC is collaborating with state and local health officials there by interviewing ill people about their exposure two weeks before becoming sick and identifying a cluster of those who reported eating at the same restaurant.

“The preliminary analysis of results from this ongoing cluster investigation in Texas does not show a connection to salad mix, leafy greens, and salad mix components produced at Taylor Farms de Mexico,” the latest CDC update reported. Officials with the U.S. Food and Drug Administration (FDA), along with Mexican government authorities, did an environmental assessment at the firm’s processing facility from Aug. 11-19 and also at five farms identified through traceback information from the investigation. According to the agency, officials found that conditions and practices at the facility and the farms during the assessment “were in accordance with known food safety protocols.” On Aug. 25, Taylor Farms resumed export of salad mix, leafy greens and salad mix components to the U.S. The firm had voluntarily stopped production and shipment of these food products on Aug. 9. CDC noted that the findings in Texas differ from results found in Iowa and Nebraska, which linked some Cyclospora cases to eating a bagged salad mix from Taylor Farms at certain restaurants. “It is not unusual to recognize outbreaks that happen in the same season but are due to different foods. As in 2013 and in years past, most cases and outbreaks of cyclosporiasis in the United States are detected in spring and summer months. Not all cases during the same time of year are necessarily caused by the same exposure,” the Monday update stated. There are no available lab tests which can distinguish different strains of Cyclospora cayetanensis, although CDC and other groups are working on developing some. If such tests were available, officials could quickly tell one strain from another, identify whether Cyclospora cases are linked and point to potential sources of the infection. The investigation into the Cyclospora outbreak continues. Most onset of illness dates ranged from mid-June through mid-July and 43 people have reported being hospitalized. No deaths have been reported.