USDA Issues Health Alert on Ground Turkey Which Might Be Linked to Salmonella Outbreak

USDA-FSIS is issuing a public health alert for approximately 211,406 pounds of raw ground turkey products, produced by Plainville Brands, LLC, a Pennsylvania establishment, due to concerns the products may have caused Salmonella Hadar illness. This come as as CDC investigates a multistate outbreak of 28 Salmonella Hadar illnesses in 12 states with onset dates ranging from December 28, 2020 through March 4, 2021. "The traceback investigation for one case patient identified the patient consumed ground turkey produced by Plainville Brands, LLC. An intact, unopened package of Plainville Brands’ ground turkey collected from this case-patient’s home tested positive for Salmonella Hadar and was closely related genetically to the sample from the patient. Evidence collected to date does not link all illnesses to this establishment."

https://www.fsis.usda.gov/recalls-alerts/fsis-issues-public-health-alert-raw-ground-turkey-products-linked-salmonella-hadar
FSIS Issues Public Health Alert for Raw Ground Turkey Products Linked to Salmonella Hadar Illness

WASHINGTON, APRIL 10, 2021 – The U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) is issuing a public health alert for approximately 211,406 pounds of raw ground turkey products, produced by Plainville Brands, LLC, a Pennsylvania establishment, due to concerns the products may have caused Salmonella Hadar illness. A recall was not requested because it is believed that the products are no longer available for consumers to purchase.

GA Establishment Recalls RTE Diced Chicken Linked to Listeria Outbreak in Canada

Tip Top Poultry, Inc., a Rockmart, Ga. establishment, is recalling approximately 135,810 pounds of fully cooked  frozen, diced, and mechanically separated ready-to-eat chicken products after it was s discovered on August 17, 2019, by Canadian Food Inspection Agency that may be adulterated with Listeria monocytogenes.  The Canadian buyer recalled their Rosemount branded product on August 19th.

https://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2019/recall-085-2019-release
Tip Top Poultry, Inc. Recalls Fully Cooked Poultry Products due to Possible Listeria Contamination 
Class I Recall 
085-2019 
Health Risk:High 
Aug 20, 2019

Ongoing Salmonella Outbreak Associated with Raw Turkey Products

There is an ongoing Salmonella outbreak linked to raw turkey products.  Going back to November of 2018, there are now 279 cases reported with 107 hospitalizations and one death associated with the outbreak strain , Salmonella Reading.   There have been 4 recalls - 2 for ground turkey and 2 for raw pet food.   A single, common supplier of raw turkey products or of live turkeys has not been identified so it is thought that it might be widespread in the turkey industry.

CDC Investigation Report
https://www.cdc.gov/salmonella/reading-07-18/index.html
Outbreak of Multidrug-Resistant Salmonella Infections Linked to Raw Turkey Products
Español (Spanish)
Posted February 15, 2019 at 3:00 PM EDT

Raw Ground Turkey Recalled After Linked to Salmonella Outbreak

Jennie-O Turkey, a Barron, Wis. establishment, is recalling approximately 91,388 pounds of raw ground turkey products after being linked to a Salmonella outbreak with 164 cases in 35 different states.   According to the USDA report, "The patient tested positive for Salmonella Reading and the sample from the ground turkey matches the outbreak strain."

The good news is that the recall does not involve whole turkeys at this point, so it should not impact Thanksgiving turkey purchases.  However, the investigation is ongoing and it seems that some people who became ill handled live turkeys.  So it is important to use proper procedures for handling and preparing whole turkey products, especially during our Thanksgiving holiday.  From the USDA report, "Patients have reported eating different types and brands of turkey products purchased from many different stores, handling raw turkey pet food and/or raw turkey, or working with live turkeys or living with someone who handled live turkeys."

https://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2018/recall-112-2018-release
Jennie-O Turkey Store Sales, LLC Recalls Raw Ground Turkey Products due to Possible Salmonella Reading Contamination 
Class I Recall
112-2018
Health Risk: High
Nov 15, 2018

Salmonella Outbreak Linked to Kosher Chicken Responsible for 17 Cases Including 1 Death

Further information was provided by CDC for the Health Alert that was posted last week regarding Salmonella infections linked to kosher raw chicken sold by a PA kosher poultry facility.   CDC reports that there are 17 cases with 8 hospitalizations and 1 death.

CDC Investigation Notice
https://www.cdc.gov/salmonella/chicken-08-18/index.html
Outbreak of Salmonella Infections Linked to Chicken
Posted August 29, 2018 at 11:30 AM ET

Salmonella in Turkey Likely Cause of Catered Thanksgiving Luncheon Outbreak

As a follow-up to a Salmonella outbreak associated with a catered Thanksgiving event in GA, the source of the outbreak is reported as......turkey.   In the outbreak, 5 were hospitalized and 70 received medical treatment.

The event was catered by a pizza shop / bistro. While this shop produces many different Italian specialty dishes, turkey is not one of the items listed on the catering menu.  So with the large number of people attending (1800) and preparing an item not normally prepared, perhaps the demands of this event were beyond the capability of the bistro?  Small misses, an undercooked bird or cross contamination from unclean food contact surfaces, could have led to Salmonella being in the served product.

The Daily Tribune News
http://www.daily-tribune.com/newsx/item/9520-food-source-identified-in-toyo-tire-salmonella-outbreak
Food source identified in Toyo Tire salmonella outbreak
06 Dec 2017  Written by  Staff Report

PA Establishment Recalls Raw Poultry Product for Foreign Metal Contamination

A Mifflintown, Pa. poultry establishment, is recalling approximately 10,839 pounds of raw poultry products that may be contaminated with metal pieces.  According to the report, "The problem was discovered on November 2, 2017 by an establishment employee who observed metal foreign material in a chicken breast while performing routine duties. The establishment took corrective actions to recover products before reaching commerce."  So not sure why a recall needed to be issued since it appears the product did not leave the building.

USDA Recall Notice
https://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2017/recall-119-2017-release
Empire Kosher Poultry Inc. Recalls Chicken Products Due To Possible Extraneous Material Contamination 
Class I Recall
119-2017
Health Risk: High
Nov 9, 2017

Pew Releases Report on Making Meat and Poultry Safer

Pew Charitable Trusts, a non-profit organization dedicated to encourage responsive government and support scientific research on a wide range of issues including food safety, released a report on making meat and poultry safer.  A few of their recommendations:

• Government agencies should fund research into how to best manage herds or flocks to maintain animal health and keep harmful bacteria out, including the use of clean feed, vaccines, and prebiotics and probiotics.
• Regulatory agencies should provide incentives for the implementation of pre-harvest food safety interventions
• Industry should consider individual pre-harvest interventions within the larger context of managing the health of the herd or flock and implement adequate controls to protect animal health and keep pathogens out,
• All stakeholders should develop information technology infrastructure and capacity to encourage sharing of efficacy and safety data among industry, academia, governmental researchers, and regulatory agencies

Good for them.  Now just need some funding to make it more of this happen.

The full report can be found here.  Good reference information on pre-harvest interventions.

Pew Charitable Trusts - Press Release 

http://www.pewtrusts.org/en/about/news-room/press-releases/2017/07/17/pew-safer-meat-requires-reducing-risks-where-food-animals-are-raised
Pew: Safer Meat Requires Reducing Risks Where Food Animals Are Raised
Report highlights effective measures to decrease contamination on farms and feedlots
July 17, 2017
Safe Food Project

Backyard Chicken Flocks Result in Numerous Salmonella Outbreaks

CDC reports that since the beginning of this year, there have been 8 Salmonella outbreaks related to backyard chickens. Within that, there have been 372 people infected and 71 of those cases resulting in hospitalization.

Poultry is a risk for Salmonella as well as Campylobacter.  People with backyard flocks, they are apt to treat the birds more as pets than farm animals, and with that, forget the need for proper personal hygiene including proper washing of hands, changing of clothes that are poop stained, and even removing shoes after stepping in bird dropping.  And even further, people increase the risk when they allow the birds to come inside their house or they snuggle with the birds.

CDC Zoontotic Diseases - Outbreak Advisory
https://www.cdc.gov/zoonotic/gi/outbreaks/livepoultry.html
Multistate Outbreaks of Human Salmonella Infections Linked to Live Poultry in Backyard Flocks, 2017

Super Bowl, Chicken Wings and Salmonella

During Super Bowl Sunday, people will eat approximately 1.3 billion chicken wings.  Food service outlets such as Buffalo Wild Wings and Wing Zone will sell 2 to 4 times the amount they normally sell.  For many consumers watching the game at home, they will prepare their own wings, probably for the first time.

Just as we worry about turkey preparation at Thanksgiving, chicken wing preparation on Super Bowl Sunday becomes a concern for foodborne illness.  Why?

• Chicken parts have been found to contain more Salmonella than whole chickens.  While Salmonella is a concern, Campylobacter actually has a higher prevalence on chicken.
• Food service operations will be handling a lot more chicken wings than they normally handle. This may increase the risk of undercooking or cross contamination during handling especially at peak times (such as an hour or two before kickoff).
• People cooking chicken wings at home may also undercook them or contaminate them through mishandling.  This risk is increased when 1) people are doing it for the first time, 2) people are unskilled in the art of chicken wing preparation,  3) people are working with a larger quantity than they are normally use to handling, 4) people have enjoyed one-too-many adult beverages, and 5) a combination of these factors.

Now, we can't let the worry of bacterial contamination stop us from enjoying eating chicken wings during the Super Bowl and (although it would have been much more enjoyable if guys wearing the Black and Gold were playing), and we certainly don't want to have post-game worship sessions with the porcelain throne.  So here are some simple measures:

• Make sure you wings are cooked. When cooking them yourself, check with a thermometer to ensure all wings have reached an internal temperature of 165F or higher..  When purchasing, make sure there is no pink and that the meat is not rubbery.  Better overcooked than undercooked.
• If undercooked, do not eat.  The large amount of alcohol consumption will not save you and may reduce your ability to resist that savory, burning flavor.
• If you have not cooked wings before, consider buying fully cooked wings and then all you have to do is properly reheat.  
• If ordering wings at a foodservice establishment, whether ordering to eat there or to-go, order early. This will help you avoid the rush, and give you time to take corrective action if not properly cooked. 
• If making wings, cook them earlier in the day,....before your guests arrive, before you consume beverages, and while you can concentrate on what you are doing.  With this, be sure to check the temperature and use clean surfaces for the cooked wings.

Other things to remember when handling food...., Keep foods at the right temperature if you will be serving for a number of hours...keep hot foods hot (>140F) and cold foods cold (<40F).  Make sure leftovers get into the refrigerator.  Do not let foods, especially cooked meat, sit out at room temperature for more than a hour or two.  Clean as you go to help prevent cross contamination.

USDA News Release
https://www.usda.gov/wps/portal/usda/usdahome?contentid=2017/01/0011.xml&navid=NEWS_RELEASE&navtype=RT&parentnav=LATEST_RELEASES&edeployment_action=retrievecontent
Beat Foodborne Illness this Super Bowl

Turkey Products Recalled for Unidentified Black Substance

A Michigan establishment is recalling 54000 pounds of turkey products after a customer complaint was received for a black substance.  This is a foodservice item so likely this was discovered by a retailer or foodservice operator.  The black substance has not yet been identified.



USDA / FSIS Recall Notice
http://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2016/recall-097-2016-release
Michigan Turkey Producers Recalls Turkey Products Due To Possible Foreign Matter Contamination
Class I Recall 097-2016
Health Risk: High Oct 15, 2016

Backyard Chickens and Eggs - Beware of the Salmonella Risk

In two news stories this week - one on raising chickens at home and the other on eggs from small chicken flocks - there is discussion on the higher risk for Salmonella.

In the Post article, people raising chickens at home threat the chickens more like pets.  Many people will cuddle or kiss baby chicks and nearly half of the patients who contracted Salmonella from the chickens allowed the chickens into the house (and some into the bedroom).

Penn State conducted a large survey looking at the prevalence in Salmonella in eggs which were purchased from farm stands across the state.  These eggs were from small chicken flocks and fall outside of regulations for controlling Salmonella.  The survey found that 2% of the eggs tested were positive for Salmonella.  The contamination was primarily found inside the egg.  For commercial egg producers, this number is less than 0.5%.

Salmonella is a natural contaminate of chickens, and unless carefully controlled, it can be passed to humans through handling of the chickens or through mishandling or undercooking of the eggs.   Commercially, Salmonella is controlled through diet (including probiotics), house maintenance procedures, and Salmonella testing.  With backyard flocks, these controls are normally not in place.  Another risk, not discussed in these articles, is Campylobacter.  This has been shown to have a higher prevalence in small flocks as well.

This is not saying that people should not raise chickens or consume their eggs, but people have to be aware of the risk.  Keep chicken in the coup.  Wash your hands after handling the chicken.  Cook the eggs and the chicken to the proper temperature.  No Rocky breakfast drink with these eggs, not unless you plan your next bout at the American Standard Bowl.

Penn State News
http://news.psu.edu/story/425880/2016/09/14/research/eggs-small-flocks-just-likely-contain-salmonella-enteritidis
Eggs from small flocks more likely to contain Salmonella enteritidis
By Jeff Mulhollem
September 14, 2016

Chicken Nuggets Recalled Due to Foreign Material

Foster Poultry is recalling 220,000 lbs of chicken nuggets because of the potential for foreign material - blue plastic and black rubber.  The problem was discovered due to consumer complaints received by the company.

So far this year there have been a number of recalls due to foreign materials inclusion in product including another cook poultry product last month.  These are extremely expensive mistakes that may not be given their due when complaints are received.  These recalls should be a siren to evaluate consumer complaints and ensure that corrective action is being completed.

  

FSIS News Release

http://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2016/recall-033-2016

Foster Poultry Farms Recalls Poultry Products Due To Possible Foreign Materials Contamination

Class I Recall 033-2016

Health Risk: High Apr 29, 2016

En Español

 

Cooked Poultry Products Recalled Because of Foreign Material

Pilgrim's Pride is recalling 4.5 million pounds of cooked chicken products, institutional or foodservice packs, due to the potential for foreign matter.  The issue was initially identified by customer complaints received by the company, and after notifying FSIS, FSIS then identified additional consumer complaint issues.  No injuries have been reported.

The recalled product has the EST. 20728 posted, indicating the product came out of their Waco TX processing facility.  The period of time is 18months from August of 2014 to March of 2015.

This is a surprising amount of product in a very large time frame to be included in a Class 1 recall, especially considering there were no injuries reported.  This is the expansion of the April 7th recall that focused on institutional packs of chicken nuggets.



USDA Recall Notice
http://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2016/recall-027-2016-expanded
Pilgrim’s Pride Corp. Recalls Poultry Products Due To Possible Foreign Matter Contamination
Class I Recall 027-2016 EXP
Health Risk: High Apr 26, 2016

Breaded Chicken Product Recall Expanded Due to Salmonella Presence in Facility

Aspen Foods is expanding an recall for stuffed and breaded chicken products due to potential Salmonella contamination.  The initial recall issue in July was for close to 2 million pounds of product.  This recall is for product produced after the company had the first recall and was issued because USDA sampling found that the responsible strain of Salmonella was still in the facility.

Facilities with a Salmonella issue can find that once it becomes endemic within the facility, it can be very difficult to eliminate. 

This is not a ready-to-eat product, but one that appears to be one.  Thus the concern for Salmonella being present.



USDA Recall Notice
http://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2015/recall-101-2015-release-expansion
Aspen Foods Recalls Frozen, Raw, Stuffed & Breaded Chicken Products Due to Possible Salmonella Enteritidis Contamination
Class I Recall 101-2015 expansion
Health Risk: High Oct 2, 2015

Congressional and Public Affairs   Gabrielle N. Johnston (202) 720-9113

EDITOR’S NOTE: This release is being reissued to expand the July 15, 2015 recall to include additional products. After further analysis, Aspen Foods chose to recall products in an effort to prevent additional illness. Details of this release were also updated to reflect a change in poundage and distribution area.

WASHINGTON, October 2, 2015 – Aspen Foods, a Chicago, Ill. establishment, is recalling approximately 561,000 pounds of frozen, raw, stuffed and breaded chicken products that appear to be ready-to-eat (RTE) and may be contaminated withSalmonella Enteritidis, the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) announced today.

Poultry Products Recalled Due to Metal Shavings Generated by Ice Machine

A Mississippi establishment is recalling approximately 550,000 lbs of poultry products after metal shavings were found by one of their customers.  The manufacturing established reported that a faulty ice machine was to blame.  The product being large cases and combos, so this indicates the product was packed on ice.

The ice machine....that neglected piece of equipment.  Whether packing product on ice, adding ice as an ingredient to facilitate cooling, or adding to our beverage, ice is just as much as part of the process as the other ingredients used.  Ice machines have often been cited for high microbiological counts when the machines are not cleaned.  Here, a malfunctioning machine had metal-on-metal contact, probably in the ice chopper/flaker that generated the metal shavings.

In these cases, ice machines are part of the process and need to identified as a source for microbiological, physical, and probably even chemical hazards.  Good preventive maintenance and periodic quality checks should be included with regard to controlling metal as a physical hazard,

USDA Recall Notice
http://www.fsis.usda.gov/wps/wcm/connect/FSIS-Content/internet/main/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2015/recall-124-2015-release
Sanderson Farms Recalls Poultry Products Due To Possible Foreign Matter Contamination
Class I Recall 124-2015
Health Risk: High Sep 24, 2015
En Español

Congressional and Public Affairs  Katherine Scheidt   (202) 720-9113

WASHINGTON, Sept. 24, 2015 – Sanderson Farms, a Hazlehurst, Miss. establishment, is recalling approximately 551,090 pounds of poultry products that may be contaminated with extraneous metal materials the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) announced today.

USDA Proposes Salmonella and Campylobacter Performance Standards for Poultry Parts and Ground Poultry

 USDA has proposed setting performance standards for poultry processors on raw ground poultry as well as raw poultry parts (breasts, legs, breasts and wings). A performance standard for pathogens is a level of positive samples a facility can have. USDA then tests product at the facility to see whether they are in compliance. This puts pressure on the facility to put measures in place to reduce the prevalence of pathogens thus having a positive impact on safety.

USDA performance standards are in place for whole poultry, but as with the Foster Farms outbreak, numbers can increase during further processing such as cutting into parts or grinding. And these products, ground and parts, represent a big proportion of the product people buy.

These performance standards will allow some level of Salmonella and Campylobacter to still be present, but in lowering the level there, the USDA hopes to reduce the number of illnesses that occur.  That being said, it still important the people handle chicken in a way to prevent cross contamination and cook it to eliminate pathogens that may be present.

USDA News Release
 http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=2015/01/0013.xml
Release No. 0013.15
Contact: Office of Communications (202)720-4623
USDA Proposes New Measures to Reduce Salmonella and Campylobacter in Poultry Products
New Standards Could Help Prevent an Estimated 50,000 Illnesses Annually

WASHINGTON, Jan. 21, 2015 -- The U.S. Department of Agriculture's (USDA) Food Safety and Inspection Service (FSIS) today proposed new federal standards to reduce Salmonella and Campylobacter in ground chicken and turkey products as well as raw chicken breasts, legs and wings. Development of these new standards is a major step in FSIS' Salmonella Action Plan, launched in December 2013 to reduce Salmonella illnesses from meat and poultry products.

As US Poultry Industry Braces for the Potential of Avian Flu, H5N2, People Not at Risk

Avian influenza has been found in wild birds on the US border.  USDA has not found it in in US poultry, but the strains H5N2 and H5N8 have been found in Canadian and European flocks.  While these strains are highly pathogenic to birds, they are not considered a risk to people.
 
Migratory birds such as ducks are a risk factor for spreading the virus to the US poultry population.  Once infected, the flock is often culled to eliminate further risk of spreading the virus.

Just this past year, the pork industry suffered the fate of the PED virus, or Porcine epidemic diarrhea virus.  PEDV causes severe diarrhea in pigs and has a high lethality in piglets, but poses no risk to other animals or humans.   PED and Influenza are different types of viruses. PED is from the Coronaviridae family of enveloped, positive-stranded RNA viruses.  Influenza is an Orthomyxovirus.

CIDRAP
H5N2, H5N8 avian flu viruses surface in US
Robert Roos | News Editor | CIDRAP News
http://www.cidrap.umn.edu/news-perspective/2014/12/h5n2-h5n8-avian-flu-viruses-surface-us
Dec 16, 2014

US authorities today reported finding wild birds in Washington state infected with two different highly pathogenic avian influenza (HPAI) viruses, H5N2 and H5N8, raising questions about possible connections with recent H5N2 outbreaks across the border in Canada and with an Asian H5N8 strain that is now hitting European poultry farms.

In reports to the World Organization for Animal Health (OIE), the US Department of Agriculture (USDA) said H5N2 was found in a wild pintail duck, while H5N8 was found in a captive wild gyrfalcon that was fed on hunter-killed birds. Both birds were in Whatcom County, Washington, which borders the Abbotsford area of British Columbia, the site of recent H5N2 outbreaks in poultry.

Breaded Chicken Product Recalled After Linked to Cluster of Salmonella Illnesses

A Chicago based firm is recalling partially prepared breaded chicken breast product - Chicken Kiev after that product was linked to cluster of Salmonella illnesses.

Although this product is partially cooked by the processor (in order to set the breading), it still needs to be further cooked by the consumer as per the cooking instructions.

But it is easy to see where consumer issues can occur regarding undercooking.   For one, the product is frozen, so when the consumer begins with frozen product, they may not cook it long enough in order to achieve the proper internal temperature. Along with this, many people do not use a thermometer in order to ensure that temperature is met. 

Another issue can be related to the fact that breaded products often look like they are fully cooked. This is because the par-cooking that sets the breading gives it a finished cooked appearance.

Salmonella enteritidis is a strain most often associated with eggs, although we can see it in chicken meat as well.
 
 
 
USDA News Release
http://www.fsis.usda.gov/wps/portal/fsis/topics/recalls-and-public-health-alerts/recall-case-archive/archive/2014/recall-073-2014-release
Illinois Firm Recalls Chicken Products Due to Possible Salmonella Enteritidis Contamination
Class I Recall 073-2014
Health Risk: High Oct 24, 2014
Congressional and Public Affairs  Benjamin Bell   (202) 720-9113 

WASHINGTON, October 24, 2014 – Aspen Foods Division of Koch Meats, a Chicago, Il., based establishment, is recalling 28,980 pounds of chicken products that may be contaminated with a particular strain of Salmonella Enteritidis, the U.S. Department of Agriculture’s Food Safety and Inspection Service (FSIS) announced today. FSIS requested Aspen Foods conduct this recall because this product is known to be associated with a specific illness cluster.

Eggs from Free Range Chickens - No Sunny Side Up

It is the scene from Rocky....he is preparing for the big fight, and he starts his day by knocking back a half dozen raw eggs in a glass.   Well, hopefully those where conventionally produced eggs and not eggs from free range chickens.

In a study published in Food Control, chicks were separated after hatch...some went to live the life on the open range while the other half were stuck in conventional cages.  And as you might predict, the eggs from free range chickens had higher levels of Salmonella (2.6% vs 0 for conventional) and Campylobacter (26.1% versus 7.6% for conventional).  This is because free range chickens are more apt to come into contact with biological contaminants and pass those contaminates to the eggs.  (Additionally, conventional eggs are washed with a high pH solution, which would further reduce the level of contamination.)

This is not a beat down on Free Range eggs, but people need to recognize the higher risk for eggs from free range chickens, which are often purchased at farmers's markets, farm stands, and such.  If buying eggs that are not conventionally produced, you can reduce the risk of illness by properly cooking (over hard or scrambled) and proper handling the eggs.

Food Control 
Volume 47, January 2015, Pages 161–165
http://www.sciencedirect.com/science/article/pii/S0956713514003673
Microbiological contamination of shell eggs produced in conventional and free-range housing systemsM.A. Parisia, J.K. Northcutta, , , D.P. Smithb, E.L. Steinberga, P.L. Dawsona