In its annual report summing up the latest trends with pathogens that are common sources of foodborne illness, the Centers for Disease Control and Prevention (CDC) said today that the incidence of most illnesses increased in 2018, especially Cyclospora infections.
A team from the CDC and partners in 10 states that are part of the FoodNet surveillance network looked at levels for 2018 and compared them with levels for 2015 through 2017. The pathogens they tracked included Campylobacter, Cryptosporidium, Cyclospora, Listeria, Salmonella, Shiga toxin-producing Escherichia coli (STEC), Shigella, Vibrio, and Yersinia. They published their findings today in the latest edition of Morbidity and Mortality Weekly Report.
In preliminary findings for 2018, the FoodNet system flagged 25,606 infections, 5,893 hospitalizations, and 120 deaths. They note that the incidence for most infections is rising, including Campylobacter and Salmonella. However, they added an important caveat that some of the increase might be partly due to the increased use of culture-independent diagnostic tests (CIDTs), which can identify pathogens not regularly found by other testing methods — complicating data interpretation.
Campylobacter, Salmonella still most common illnesses
Campylobacter, with poultry as a major source, is still the most commonly identified foodborne illness since FoodNet tracking began in 2013. Also, the incident of Enteritidis, the most common Salmonella subtype for which poultry and eggs are often the source, has not declined over the last 10 years. Compared with 2015-2017 levels, incidence significantly increased for Cyclospora (399%), Vibrio (109%), Yersinia (58%), STEC (26%), Campylobacter(12%), and Salmonella (9%).
Produce is a major source of foodborne illness, and the authors note that in 2018, contaminated romaine lettuce triggered two E coli O157 outbreaks and a marked increase in Cyclospora infections probably reflects several factors, including produce outbreaks and continued adoption of DNA-based syndrome panel tests.
Cyclospora infections are caused by the parasite Cyclospora cayetanensis, which is spread by eating food or drinking water contaminated by feces. Symptoms occur between 2 and 14 days after ingesting food or water tainted with oocytes, and the hallmark of the disease is profuse diarrhea that can last weeks to months.
Isolate testing still important
In summing up the report, the group wrote that obtaining and subtyping isolates from sick patients is becoming an increasing burden on state health departments, but it is critical for doing surveillance that is key for detecting and investigating outbreaks.
They said steps that can decrease foodborne illnesses includes more efforts to target Campylobacter contamination of chicken, strengthening safety during egg production, vaccinating poultry against Salmonella Enteritidis, decreasing Salmonella in produce, poultry, and meat, and continuing the implementation of the Food Safety Modernization Act.
Apr 26 MMWR report
Mar 23, 2018, CIDRAP News story "CDC says some FoodNet Salmonella infections rising"