Better testing fuels US meat pathogen reports

By Rod Addy

- Last updated on GMT

Rapid testing should be followed up with lab tests, said the CDC
Rapid testing should be followed up with lab tests, said the CDC

Related tags Foodborne illness Bacteria Beef Lamb Pork Poultry

Reported US infections linked to pathogens Yersinia and Shiga toxin-producing E.coli, commonly contaminating meat products, grew in number in 2016, but experts blamed better testing, not more people becoming sick. 

In its report on bacterial foodborne illnesses, published on 21 April, the US Centers for Disease Control (CDC) stated: “Reported Yersinia, Cryptosporidium, and Shiga toxin-producing E.coli infections increased. These increases are likely due to newly available rapid tests that make infections easier to diagnose, rather than to a true increase in illness.”

Elsewhere, there was good news concerning Salmonella typhimurium infections, often linked to beef and poultry, which decreased by 18% in 2016 compared with the average for 2013-2015.

The CDC claimed the continuing decreases in Salmonella typhimurium might be due to regulatory action to reduce Salmonella contamination in poultry and vaccination of chicken flocks by producers.

For the first time, the 2016 report also included foodborne bacterial infections diagnosed only by rapid diagnostic tests in FoodNet sites. Previously, the report counted foodborne bacterial infections confirmed only by traditional culture-based methods in the total numbers.

Note of caution

However, the CDC sounded a note of caution: the faster tests could have immediate benefits for treatment, but miss important information. They do not collect information needed to determine if an infection is antibiotic-resistant or if it is linked to an outbreak.

Positive results on rapid tests can be followed-up by culture-based tests to get detailed data, but often are not, according to the report.

“We need foodborne-illness trend data to monitor progress toward making our food supply safer,”​ said Robert Tauxe, director of CDC’s Division of Foodborne, Waterborne, and Environmental Diseases. “It’s important that laboratories continue to do follow-up cultures on CIDT​ [culture-independent diagnostic test]-positive patients so public health officials can get the information needed to protect people from foodborne illness.”

The FoodNet system – a collaboration between the CDC, 10 state health departments, the Food Safety & Inspection Service (FSIS) and the Food and Drug Administration (FDA) – is developing tools to track progress accurately in reducing incidences of foodborne illness. It hopes these tools will determine how far increasing disease reports are fuelled by better testing and how far they are down to increasing instances of the diseases themselves.

Campylobacter, Salmonella

Campylobacter and Salmonella caused the most reported bacterial foodborne illnesses in 2016, according to preliminary data published today in CDC’s Morbidity and Mortality Weekly Report. CDC’s Foodborne Diseases Active Surveillance Network (FoodNet) report provides the most up-to-date information about foodborne illnesses in the US.

FoodNet collects data on 15% of the US population. FoodNet sites alone reported 24,029 foodborne infections, 5,512 hospitalisations, and 98 deaths in 2016.

The numbers of reported illnesses by germ were:

• Campylobacter (8,547)
• Salmonella (8,172)
• Shigella (2,913)
• Shiga toxin-producing E.coli (1,845)
• Cryptosporidium (1,816)
• Yersinia (302)
• Vibrio (252)
• Listeria (127)
• Cyclospora (55).

Commenting on the latest CDC report, the FDA welcomed improvements in detecting, and responding to, foodborne illness. However, it stressed the main priority remained the prevention of infection.


Final rules being implemented under the FDA Food Safety Modernization Act focus on prevention. The FDA said it would continue to work closely with government agencies, tribal and territorial partners to support industry compliance with the new requirements.

In 2016, prevention measures included FSIS finalising new performance standards for reducing harmful bacteria in chicken parts and ground poultry. FSIS expects these actions could prevent as many as 50,000 illnesses each year caused by Salmonella and Campylobacter in chicken and turkey products.

“Our new performance standard for chicken parts is a perfect example of the type of proactive, prevention-based food policies that we’re focused on at FSIS – policies that are based on science, that are supported by strong data, and that will truly improve public health,”​ said Al Almanza, FSIS administrator.

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