ATLANTA – Foodborne illness was more prevalent in 2018, according to preliminary surveillance data from the Centers for Disease Control (C.D.C.) and Prevention. Incidents of Campylobacter, Salmonella and Cyclospora infections increased last year, according to FoodNet 2018 preliminary data released by the C.D.C. The increases were due, in part, to more infections being diagnosed using culture-independent diagnostic tests (C.I.D.T.s), but the C.D.C. 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.  More infections are being diagnosed, the C.D.C. said, because more laboratories use C.I.D.T.s to detect Campylobacter and other pathogens. C.I.D.T.s 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.

Reducing Campylobacter infections will require more knowledge of how case patients are becoming infected, the C.D.C. said. 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,” the C.D.C. 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 are not decreasing despite regulatory programs aimed at reducing Salmonella in poultry and eggs.

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% in 2018 compared with 2015-2017. However, increased use of C.I.D.T.s may also be linked to an increase in the number of non-O157 STEC infections diagnosed, the C.D.C. noted.

“With the increasing use of C.I.D.T.s, clinical laboratories now commonly determine if a specimen contains a Shiga toxin, and then test the specimen for O157,” the C.D.C. said. “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, the C.D.C. reported. Investigators are using D.N.A.-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, the C.D.C. said, and infections have been increasing for years. The increase in Yersinia infections is likely due to more laboratories testing for the bacteria.