ATLANTA – Preliminary surveillance data for incidents of foodborne illness show that 2018 was not a good year. Incidents of Campylobacter, Salmonella and Cyclospora infections increased last year, according to FoodNet 2018 preliminary data released by the Centers for Disease Control (CDC) and Prevention report. CDC explained the increases were due, in part, to more infections being diagnosed using culture-independent diagnostic tests (CIDTs), but the agency noted the possibility that the number of infections actually is increasing.

Campylobacter infections were the commonly identified infection in FoodNet sites since 2013 with poultry being the major source of infection, CDC reported.  More infections are being diagnosed, CDC said, because more laboratories use CIDTs to detect Campylobacter and other pathogens. CIDTs detect the presence of a specific genetic sequence of an organism. The tests produce results more rapidly because they do not require isolation and identification of living organisms.

CDC said reducing Campylobacter infections will require more knowledge of how case patients are becoming infected. The pathogen can contaminate raw chicken or poultry juices, and cross-contamination can impact hands, other foods or kitchen equipment.

“Focusing on interventions throughout the food production chain that reduce Campylobacter bacteria in chicken could lead to fewer illnesses in people,” CDC said. “Whole genome sequencing might help us figure out the contribution of various sources and help target interventions.”

Salmonella infections, the second most common infection, also appear to be increasing, according to the preliminary report. The most common Salmonella serotypes were Enteritidis, Newport and Typhimurium. Additionally, Enteritidis infections aren’t decreasing despite regulatory programs aimed at reducing Salmonella in poultry and eggs.

CDC said the best interventions can depend on serotype, but overall Salmonella infections could be decreased by focusing prevention measures on Enteritidis and other common serotypes, on poultry and on raw produce.

The incidents of STEC infections increased 26 percent in 2018 compared with 2015-2017. However, increased use of CIDTs may also be linked to an increase in the number of non-O157 STEC infections diagnosed, CDC noted. “With the increasing use of CIDTs, clinical laboratories now commonly determine if a specimen contains a Shiga toxin, and then test the specimen for O157,” the agency explained. “If they do not find O157, they assume a non-O157 STEC is present. They can then send the specimen to a specialized laboratory to determine which non-O157 STEC serogroup is present.”

Incidents of Cyclospora infections spiked in 2018 due mainly to large outbreaks associated with produce which is a major source of foodborne illness, CDC reported. Investigators are using DNA-based syndrome panel tests for the pathogen which is helping to find more infections.

Other pathogens noted as on the rise include Vibrio and Yersinia. Rising temperatures of coastal waters contribute to growth and persistence of Vibrio bacteria, CDC said, and infections have been increasing for many years. The increase in Yersinia infections is likely due to more laboratories testing for the bacteria.