World Health Day | barfblog

I’m collaborating with Matt Shipman, public information officer at NC State University and curator of The Abstract, on a set of food safety-related posts from other NCSU folks as we roll toward WHO’s World Health Day on April 7– which is focused this year on food safety. Here’s a post on Listeria’s history with produce by Danisha Garner, a graduate student in NC State’s Department of Food, Bioprocessing and Nutrition Sciences.

In the United States and other industrialized nations, consumption of fresh fruits and vegetables is considered a key component of a healthy diet.

There are many benefits to eating fresh produce such as receiving adequate vitamins and minerals, reducing the risk of heart disease, lowering blood pressure, and preventing some types of cancer. Even healthy foods, however, can be vehicles for foodborne pathogens. Indeed, fresh produce is now considered a major contributor to human foodborne disease, and an increasing number of produce-associated foodborne disease outbreaks have occurred in recent years.

An especially worrisome trend is the increase in outbreaks of listeriosis, involving the pathogen Listeria monocytogenes.

Danisha Garner. Photo courtesy of Danisha Garner.

What Is Listeriosis?

Although it is relatively uncommon, human listeriosis remains a major public health concern due to high hospitalization and death rates. In fact, it has the highest hospitalization rate of all foodborne pathogens in the U.S. and is the third largest contributor to deaths from foodborne illness. Symptoms of infection can be severe and include septicemia, meningitis, stillbirths and abortions. At high risk are the elderly, pregnant women and their fetuses, and patients with cancer and other immunocompromising conditions.

L. monocytogenes can be found in decaying plant material, soil and water, and has been detected on many types of fresh produce. Its reservoirs in nature remain poorly characterized but likely include soil and vegetation. Major contributors to the ability of L. monocytogenes to contaminate foods include its capacity to persistently colonize the environment and equipment of both food processing plants and produce packing sheds, and to grow even at refrigeration temperatures. Hence, foods typically implicated in human listeriosis are those that are processed, cold-stored and ready-to-eat – i.e. consumed without further treatment.

History of Listeriosis Outbreaks

The first outbreak of human listeriosis to be epidemiologically investigated (and to confirm foodborne transmission of the pathogen) involved produce (coleslaw) and took place in the Maritime Provinces of Canada in 1981. However, most subsequent outbreaks involved dairy products (especially soft cheeses) and ready-to-eat meats. Fresh produce was generally considered at low risk for listeriosis.

This situation changed dramatically in 2011, when one of the largest listeriosis outbreaks on record was traced to contaminated whole cantaloupe and resulted in a total of 147 cases of illness and 33 deaths across 28 states. This was also the first time that whole cantaloupe was found to serve as food vehicle for listeriosis. Contamination of the cantaloupes occurred in the packing facility, likely due to inadequate cleaning and sanitation of equipment. The pathogen was not recovered from the field where the melons were grown or from fruit prior to packing.

Even though additional melon-associated outbreaks of listeriosis have not been noted since the 2011 outbreak, several other produce-associated outbreaks have been documented in the U.S. since 2010. Implicated produce included diced celery (2010), sprouts (2014) and commercially produced, prepackaged caramel apples (2014). In all investigated cases, the source of contamination was the packing/processing environment or equipment. These outbreaks highlight the importance of having good sanitation practices in the packing/processing facility to prevent or reduce contamination with Listeria and other pathogens.

Research and Prevention

At NC State, several efforts are being focused on characterizing Listeria-produce associations with the ultimate goal of identifying new tools and strategies to reduce the risk of contamination.

In the Department of Food, Bioprocessing and Nutrition Science, researchers in the lab of Sophia Kathariou are collaborating with Lisa Gorski and William G. Miller at USDA-ARS to investigate genes of L. monocytogenes that mediate the pathogen’s adherence and growth on both fresh produce and on surfaces likely to be encountered in packing sheds and processing plants.

In collaboration with Christian Melander (in NC State’s Department of Chemistry) the Kathariou lab is also investigating the potential of novel compounds to prevent or disperse biofilms formed by L. monocytogenes on environmental surfaces and equipment. Such research will be critically needed for development of novel tools and strategies to ensure the safety of fresh produce and reduce the risk for human listeriosis.

More information about Listeria monocytogenes and listeriosis outbreaks can be found at http://www.cdc.gov/listeria/

Last week I gave a guest lecture to an undergraduate nutrition class at UNC-Chapel Hill on the burden of foodborne illness as sort of an introduction to how and why folks like small farmers, school garden managers, cafeteria staff address food safety.

In a lot of my talks I get looks of bewilderment when I throw up the details from Elaine Scallan (and lots of her colleagues) papers on the burden of foodborne illness. Same with when I show economic estimates from friend of barfblog and all-around-good-guy-with-hipster-glasses Mike Batz (and colleagues). Foodborne illness, is kind of a big deal (at least to us food safety nerds).

Here’s the first post:

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Food safety poses a global health problem. According to the World Health Organization, contaminated food can cause more than 200 diseases – and food- and water-borne diseases that cause diarrhea are estimated to kill two million people each year worldwide.

And food safety is not just someone else’s problem.

“Foodborne illnesses are a significant problem in the United States, with massive impacts on public health and the economy,” says Ben Chapman, a food safety expert and researcher at NC State. And the numbers back Chapman up.

According to a 2012 report from researchers at the Emerging Pathogens Institute, Resources For the Future, and the U.S. Department of Agriculture’s Economic Research Service, foodborne illness is estimated to cost the U.S. more than $14 billion annually. (The estimate takes into account factors such as medical costs and productivity losses.)

And a 2011 report from the U.S. Centers for Disease Control and Prevention (CDC) reported an estimated 9.4 million episodes of foodborne illness each year in the U.S. from known pathogens. An additional 38.4 million cases are estimated to come from unspecified or unknown pathogens. In total, foodborne illnesses are thought to contribute to 48 million illnesses annually – resulting in more than 128,000 hospitalizations and 3,000 deaths.

It is, in short, a big deal.

So what are these foodborne illnesses? And how much damage does each of them cause?

In advance of World Health Day, we wanted to explain a handful of the relevant pathogens implicated in foodborne illness.

Campylobacter: Campylobacteris a genus of bacteria, many of which can cause an illness called campylobacteriosis in humans, with symptoms including diarrhea and abdominal pain. People can contract campylobacteriosis from undercooked chicken, from cross-contamination via raw chicken, or from drinking unpasteurized milk.

According to the 2012 paper, campylobacteriosis affects 845,000 people annually in the U.S., costing the nation an estimated $1.747 billion every year and leading to 8,463 hospitalizations.

Listeria monocytogenes: This is a bacterium that causes listeriosis, which is characterized by fever, muscle aches, and sometimes by gastrointestinal problems, such as diarrhea. Listeriosis can be contracted from an incredibly broad range of foods.

According to the 2012 study, listeriosis costs the U.S. $2.577 billion annually, despite the fact that there are only 1,591 illnesses per year. But 1,455 of those illnesses require hospitalization – and 255 result in death.

Norovirus: Noroviruses are the most common cause of foodborne illness in the U.S., affecting an estimated 19-21 million people each year. Symptoms range from vomiting and diarrhea to fever and headache. Transmission comes from ingesting infected feces or vomit particles – for example, by touching a contaminated surface and then touching food or touching your mouth.

According to the 2012 study, noroviruses cost the U.S. $2 billion per year, with more than 14,000 hospitalizations and approximately 150 deaths annually. NC State is a leader in norovirus research, and home to NoroCORE – the Norovirus Collaborative for Outreach, Research, and Education. NoroCORE pulls together norovirus research from 18 institutions, with funding from the U.S. Department of Agriculture.

Salmonella enterica: This is one species of the pathogen that has myriad of subspecies and types – more than 1,400 of which are known to cause human illness. Infection with Salmonella species causes salmonellosis, with symptoms including diarrhea, fever, and cramping. Salmonellosis can be contracted from a variety of sources, ranging from poultry to peanut butter to mangoes.

According to the 2012 study, the subspecies within S. entericaalone costs the U.S. $3.3 billion each year, causing more than one million hospitalizations and almost 400 deaths annually.

What are researchers doing about this?

The four pathogens listed above are just a few of the rogue’s gallery of bacteria and viruses that can cause foodborne illness. But researchers are constantly learning more about these health risks.

“New technology and new research on pathogens, practices and prevention are improving our ability to identify and address foodborne illness,” Chapman says. “The field is really opening up. It’s an exciting time to be involved in food safety research.”

Between now and April 7, we’re planning to publish a series of posts on various aspects of food safety – what we know, what we don’t know, and what we’re working on. We also hope to offer insights to help folks lower the risk of contracting foodborne illnesses. We hope you’ll learn something new.

Note: you can find all of our posts related to food safety here.

Citations:

Batz, Michael B., Sandra Hoffmann, and J. Glenn Morris, Jr. “Ranking the Disease Burden of 14 Pathogens in Food Sources in the United States Using Attribution Data from Outbreak Investigations and Expert Elicitation” Journal of Food Protection, Vol. 75, No. 7, 2012, Pages 1278–1291. doi:10.4315/0362-028X.JFP-11-418

Scallan, Elaine, et al. “Foodborne Illness Acquired in the United States—Major Pathogens” Emerg Infect Dis, Vol. 17, No. 1, 2011. doi:10.3201/eid1701.P11101

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Tag Archives: World Health Day

Listeriosis and Produce: What’s the Connection? (via The Abstract)

The burden of foodborne illness: it’s kind of a big deal