Flies as a Vector for Foodborne Illness and Human Disease - What is the Risk?

A recent study originating from Penn State's College of Science and published in Scientific Reports evaluates the microbiome of house flies (grey) and blow flies (metallic green or blue, larvae live off of dead animals) and their ability to transfer bacteria.  But as reported in many mass media articles, the assertions drawn from this study may have people avoiding flies like the plague.

As an example from the The Telegraph
http://www.telegraph.co.uk/science/2017/11/24/flies-carry-bacteria-first-thought-warn-scientists/
Title:  Don’t eat food if a fly lands on it, as they carry more dangerous bacteria than previously thought, warn scientists

• "But a new study suggests the insects carry far more dangerous bacteria than previously thought, meaning sandwiches are best avoided if they have been contaminated by flies."
• "Flies in urban areas were found to carry more bacteria than the countryside leading scientists to suggest avoiding city parks for a picnic, and eating food into more rural locations."
• "It might be better to have that picnic in the woods, far away from urban environments, not a central park."

The metgenomic analysis of the fly microbiome  in the study does show that flies can carry a number of bacterial pathogens, however the presence may not translate to absolute risk.  Like the metagenonic analysis conducted on surfaces in the city environment  that showed the presence of  a number of different bacterial pathogens in the subway and other places, that presence doesn't mean there is a huge risk.   A fly landing on your food doesn't necessarily mean that the food is now contaminated to a point that makes it unsafe.  Or, I wouldn't skip the opportunity of having a picnic in a city park because a fly may land on my food.

So perhaps some more reasonable takeaways from the study:

• Don't swat a fly when it is on your food.  If you swat it on the counter, clean that surface.  The majority of bacteria will be in the fly or on various parts that will more likely transfer to the food or food contact surface when the fly is splattered.
• The higher transfer rate of bacteria will be from a surface the fly was just on.  So if you are eating lunch in a pasture full of cow patties where numerous flies are landing on cow poop and then landing on your sandwich, then one would consider that a higher risk than having a fly land on your sandwich when eating it in your home. See this link - https://www.hindawi.com/journals/isrn/2013/718780/
• When preparing food, especially food for others, it is important to keep flies away the best you can.  Keep doors and windows closed or screened.  It is still important to avoid risks where we can.

Scientific Reports

https://www.nature.com/articles/s41598-017-16353-x
The microbiomes of blowflies and houseflies as bacterial transmission reservoirs
Ana Carolina M. Junqueira, Aakrosh Ratan, Enzo Acerbi, Daniela I. Drautz-Moses, Balakrishnan N. V. Premkrishnan, Paul I. Costea, Bodo Linz, Rikky W. Purbojati, Daniel F. Paulo, Nicolas E. Gaultier, Poorani Subramanian, Nur A. Hasan, Rita R. Colwell, Peer Bork, Ana Maria L. Azeredo-Espin, Donald A. Bryant & Stephan C. Schuster
Scientific Reports 7, Article number: 16324 (2017)
doi:10.1038/s41598-017-16353-x
Received:29 June 2017Accepted:10 November 2017Published online:24 November 2017

Abstract

Blowflies and houseflies are mechanical vectors inhabiting synanthropic environments around the world. They feed and breed in fecal and decaying organic matter, but the microbiome they harbour and transport is largely uncharacterized. We sampled 116 individual houseflies and blowflies from varying habitats on three continents and subjected them to high-coverage, whole-genome shotgun sequencing. This allowed for genomic and metagenomic analyses of the host-associated microbiome at the species level. Both fly host species segregate based on principal coordinate analysis of their microbial communities, but they also show an overlapping core microbiome. Legs and wings displayed the largest microbial diversity and were shown to be an important route for microbial dispersion. The environmental sequencing approach presented here detected a stochastic distribution of human pathogens, such as Helicobacter pylori, thereby demonstrating the potential of flies as proxies for environmental and public health surveillance.

FDA Warns About Giving Bones and Bone Treats to Dogs

FDA issued a consumer warning about giving bones including commercially-sold bones and bone treats to dogs. Also included of course are chicken and turkey bones.

As dog owners know, some dogs can handle a bone, while others want to swallow it whole. If your dog is one that can't resist knocking back the whole bone, then even a commercially-sold bone can be a problem.  The hard part for owners is overcoming 'the stare'.

FDA Warning to Consumers
https://www.fda.gov/forconsumers/consumerupdates/ucm208365.htm
No Bones (or Bone Treats) About It: Reasons Not to Give Your Dog Bones

Bone Treats Pose Risks for Dogs 
Bone treats are real bones that have been processed, sometimes flavored, and packaged for dogs. Giving your dog a “bone treat” might lead to an unexpected trip to your veterinarian, a possible emergency surgery, or even death for your pet.

Many dog owners know not to toss a turkey or chicken bone to their dog; those bones are just too brittle. But the U.S. Food and Drug Administration (FDA) says the risk goes beyond that, especially when it comes to the “bone treats” you may see at the store.

Catered Thanksgiving Event Results in Numerous Cases of Foodborne Illness

Update - 10/27 According to a report, the causative agent was determined to be Salmonella.  No specific product was identified as the source, but it looks as though a local pizza shop was the caterer.

A catered Thanksgiving event in northern GA resulted in numerous cases of foodborne illness. At least two have been hospitalized, and the total number of cases may be as high as 1800. Reported symptoms of foodborne illness includes upset stomach, stomach cramps, diarrhea, vomiting, and fever.

No specific pathogen or suspect food has been identified at this point.

We can add this to our Thanksgivings past and foodborne illnesses outbreak list – something to consider for your holiday celebrations – warning to our late shift employees on being served food from earlier in the day.

• 2016 - C. perfrigens Identified as Cause of Thanksgiving Foodborne Illness Outbreak - Shortly after Thanksgiving, an outbreak of foodborne illness was reported in California that was linked to a Thanksgiving charity event. There were 3 deaths and another 22 others who were ill. The causative agent was found to be Clostridium perfringens, a sporeforming pathogen that can grow rapidly when food is temperature abused.
• A 2015 Thanksgiving Luncheon Becomes Scene for C. perfringens Outbreak - A CDC Report - With Thanksgiving leftovers still in the fridge, it is a good time to review a 2015 outbreak that occurred during a Thanksgiving luncheon. About 40 people who attended a catered company Thanksgiving lunch became ill with diarrhea and abdominal pain the following day (roughly 13 hours later). C. perfrignes entrotoxin was found in the patient stool samples and C. perfrigens was isolated from the turkey as well as the patients. According to the CDC report "The caterer had previously maintained a permitted facility, but reported having prepared the lunch food served at this event in an uninspected, residential kitchen. Turkeys were cooked approximately 10 hours before lunch, placed in warming pans, and plated in individual servings. Food was then delivered by automobile, which required multiple trips. After cooking and during transport, food sat either in warming pans or at ambient temperature for up to 8 hours. No temperature monitoring was conducted after cooking."
• 2012 Martha Stewart, celebrity chef and author, contracts Salmonella - Martha Stewart contracted Salmonella over Thanksgiving from mishandling food in the form of raw turkey. While we hate to see anyone become ill, having a celebrity chef come down with Salmonella can have a positive outcome. Too often we see these celebrity chefs demonstrating poor practices, whether it is inadequate hand washing, cooking to the incorrect temperatures, or canning foods using the oven technique. But my hope is that Martha will use this experience as motivator to endorse good safety practices.
• 2015 Fifteen Postal Workers Ill from Potluck Leftovers - Potlucks are one thing, but leftovers from potlucks..... In this case, 15 postal workers become ill after consuming leftovers from a potluck dinner held for 200 to honor veterans. Officials at the facility said nearly 200 employees participated in a potluck dinner Tuesday evening to honor co-workers who are veterans. Some of the food was refrigerated overnight Tuesday. Employees and managers returning to work Wednesday night helped themselves to the leftovers and after consuming them, some complained of stomach pains, officials said.
• 2014 Catered Office Party Is the Site of Staph Aureus Intoxication - Approximately 60 people became ill after attending an office party in Florida. About 25 were taken to the hospital. The catered event served turkey, ham, stuffing and green bean to some 700 people. The caterer was identified as Kitchen Divas, which from the website, appears to be a legitimate operation. It sucks when staff parties turn into 'staph' parties
• Advice on handling leftovers.

Rome News Tribune

http://www.northwestgeorgianews.com/region/health-department-investigating-likely-foodborne-illness-outbreak-at-toyo-tire/article_3e226290-ce36-11e7-bef0-03c2be8bd607.html
Health department investigating likely foodborne-illness outbreak at Toyo Tire event
Press release
11/20/17

Store Caramel Apples At Refrigeration Temperatures

Unfortunately, we are still seeing caramel apples at retail being displayed at room temperature.  Less than two years ago, a Listeria outbreak was linked to caramel apples.  It was later determined that if those apples had been stored at refrigeration temperatures, there would not likely have been an issue.

Penn State News
http://news.psu.edu/story/490097/2017/10/24/impact/caramel-apples-stored-room-temperature-extended-periods-can-pose-risk
Caramel apples stored at room temperature for extended periods can pose risk
October 24, 2017

Trader Joe's Chicken Salad Products Recalled After Complaints of Glass-like Foreign Material

Green Cusine, a CA establishment, issued a recall for 36,854 pounds of Trader Joe's chicken and turkey salad after the company received consumer complaints of glass shards / silica foreign material.

News Release
https://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2017/recall-125-2017-release
Green Cuisine Recalls Poultry Products Due To Possible Foreign Matter Contamination
Class I Recall 

125-2017
Health Risk: High 

 Nov 18, 2017

Dairy Calves Linked to Outbreak of Antibiotic Resistant Strain of Salmonella

CDC has identified an ongoing Salmonella outbreak associated with dairy calves.  The calves originated in Wisconsin.  The ongoing outbreak has progressed for some time, dating back to January 2015, with now 54 people in 15 states.  It is a multidrug resistant strain of Salmonella Heidelberg.

Dairy Herd Management
https://www.dairyherd.com/index.php/article/cdc-links-salmonella-outbreak-contact-dairy-calves
CDC Links Salmonella Outbreak to Contact with Dairy Calves
John Maday
November 16, 2017 10:18 AM

CA Firm Recalls Guacamole Product Due to Listeria Positive Sample

A California firm is recalling its 9-ounce containers of "Real Guacamole" because they have the potential to be contaminated with Listeria monocytogenes.  This issue was identified after FDA product sampling identified Listeria monocytogenes in the product.

Initially (11/15), one lot was recalled.  But with many Listeria related recalls, they get expanded.
Two days later (11/17), the company issued an expanded recall.  In the later recall notice, it stated, "The recall was necessitated by positive test results for Listeria monocytogenes on two packages out of many samples collected for the U. S. Food and Drug Administration random sample testing program."

Casa Sanchez Foods Recalls "Real Guacamole" Because Of Possible Health Risk
For Immediate Release
November 15, 2017

This Week in Mislabeled Product - Ending 11/17/17

Chicken Wraps with Undeclared Peanut and Soy - A Swedesboro, N.J. establishment, is recalling approximately 46 pounds of chicken wrap products due to misbranding and undeclared allergens  The product contains peanut and soy, known allergens, which are not declared on the product label  The problem was discovered on Nov. 15, 2017 by the firm’s quality assurance supervisor while performing verification activities. After discovering the issue, the firm immediately notified FSIS.

More Dark Chocolate Products Recalled Due to Undeclared Milk - A Marshfield, WI company is recalling 2 gingersnap products that are related to the GKI FOODS LLC Dark Chocolate Products recall because it may contain undeclared milk allergen.
Lipari Foods, LLC has also issued voluntary recall of specific dark chocolate products packaged by sister company JLM due to an undeclared milk allergen.  Products were distributed under the Weis and All Natural brand names or as generic product without branding.

Chocolates With Almonds Getting in with Non-Almond Product - A Washington firm is recalling 127 cases of Costco item # 2335, Dilettante Chocolates Espresso Blend, Espresso Beans in Semisweet, Milk and White Chocolate, because it may contain undeclared almonds. The recall was initiated after the firm discovered the chocolate covered almonds were mixed and packaged with the Dilettante Espresso Blend.  Product was distributed in packaging that did not reveal the presence of almonds.

https://www.fda.gov/Safety/Recalls/ucm584663.htm
Figi’s Issues Recall Alert Due to Undeclared Allergen (Milk) in Dark Chocolate Gingersnaps
For Immediate Release
November 9, 2017

Frozen Corn Recalled Due to the Potential for Listeria Contamination

Two supermarket chains are recalling frozen corn after their supplier, Bonduelle, a French food conglomerate, had discovered a Listeria issue in the frozen corn.

According to the Enforcement Report, the product was from Canada.  The Listeria testing was conducted by the Virginia Department of Agriculture.  The recall was classified as Class 2.

https://www.fda.gov/Safety/Recalls/ucm585550.htm
Stop & Shop Alerts Customers to Voluntary Recall of Store Brand Frozen Whole Kernel Sweet Corn
For Immediate Release
November 15, 2017