Review - The Risk of Pathogen Spillover from Wild Birds

Wild birds can carry pathogens, such as Campylobacter and Salmonella, that can become contaminants for food. Most of our concern is in the fields with crops that will receive minimal processing, but also in instances where birds gain access into our processing facilities. A recent review of the research shows that we probably overemphasize the risk, but more research is needed in understanding transmission from birds to our food systems.

"We conclude that current data do not provide sufficient information to determine the likelihood of enteric pathogen spillover from wild birds to humans and thus preclude management solutions. The primary focus in the literature on pathogen prevalence likely overestimates the probability of enteric pathogen spillover from wild birds to humans because a pathogen must survive long enough at an infectious dose and be a strain that is able to colonize humans to cause infection."

From their paper:

"Campylobacter spp. 14.8%(64/431)of North American breeding birds had Campylobacter spp. prevalence data (1+ observations) meeting our inclusion criteria 1–9 (Data S2). The species with the most observations meeting our inclusion criteria 1–9 were rock pigeon [N= 3659from 15 studies, range 6–1800 individuals tested, 0.1–70% reported prevalence, estimated prevalence 16± 5.3%(SE)],European starling[N= 2094 from 12 studies, range 1–957 individuals tested, 0–75% reported prevalence, estimated prevalence 28 ± 6.0% (SE)],...."

"Salmonella spp. were the most studied bacteria with 33% (141/431) of North American breeding birds having prevalence data (1+ observations) meeting our inclusion criteria 1–9. The species with the most observations of data meeting inclusion criteria 1–9 were herring gull [N = 12470 from 10 studies, range 1–5324 individuals tested, 0–22% prevalence,estimated prevalence 8.2± 2.2%(SE)],house sparrow [N = 5581 from 19 studies, range 2–1124 individuals tested, 0–21% prevalence, estimated prevalence 2.5 ± 0.7% (SE)], rock pigeon [N = 5458 from 30 studies, range 4–1800 individuals tested, 0–100% prevalence, estimated prevalence 4.0 ± 0.9% (SE)..."

So birds can carry pathogens, and we need to keep them out of food processing facilities, but with field crops, further work is needed before we go to the levels of habitat destruction.

Biological Reviews
https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12581
Are we overestimating risk of enteric pathogen spillover from wild birds to humans?
Olivia M. Smith  William E. Snyder  Jeb P. Owen
First published: 31 January 2020 https://doi.org/10.1111/brv.12581

What is the Likelihood That Salmonella is On Your Chicken...or Beef...or Pork

USDA FSIS released their yearly sampling results that indicate the prevalence, or percent positive samples, for raw meat products.  As FSIS points out, "These calculations may vary significantly from the actual prevalence of the population, but FSIS cannot make a more precise calculation with the data currently available."  It is important to note that this does not evaluate the amount present, only if any are present.

Beef - In ground meat, Salmonella was present in just over 2% of the samples while pathogenic E. coli was present in 0.05% of samples.  While the prevalence of E. coli is low, there is still a risk of it being present, and considering the seriousness of the illness (and the fact that Salmonella could be present as well) it still remains important to cook meat to the proper temperature.

Pork - While there is extremely low to no risk for pathogenic E. coli, there is a higher risk of Salmonella being present in pork compared to beef.  For cuts, the prevalence of Salmonella is over 7%, but in comminuted pork meat (ground, stuff used in sausages), the prevalence is 22 percent.  Cook those brats to the right temperature.

Chicken - as the chicken moves from whole to parts to ground, the prevalence increases for both Salmonella and Campylobacter.   For whole chickens, there is a prevalence of 5.8% for Salmonella and 1.9% for Campylobacter.  In mechanically separated meat, the prevalence is almost 76% for Salmonella and 23% for Campylobacter.

Turkey - the stated prevalence is lower than that for chicken with whole birds at 0.56% for Salmonella and 0.16% for Campylobacter.  Much of difference between whole turkey and chicken may be due in part to how they are sampled, with a sponge being used for turkeys and a whole bird rinse used for chickens.

In the end, the risk is there, so it remains important to properly cook raw meat and poultry products.  And of course, to use a thermometer to verify.

CDC MMWR - 2016 Outbreak of Campylobacter Linked to Undercooked Chicken Liver Mousse

In a 2016 case, 4 people became ill from Campylobacter after eating undercooked chicken liver mousse.  From the report, "During an inspection on July 15, the sous-chef solely responsible for preparing the chicken liver mousse demonstrated preparation to the CCPH food safety inspector, who observed that the sous-chef used the appearance of the livers alone to determine whether they were fully cooked. Final internal cook temperature of the largest liver measured by the inspector was <130°F (54°C), below the minimum 165°F (74°C) internal temperature deemed necessary by the Food and Drug Administration to eliminate food safety hazards"

Campylobacter is naturally found in chickens and is a risk for causing foodborne illness when there are cross contamination issues or undercooking.
CDC - MMWR
https://www.cdc.gov/mmwr/volumes/66/wr/mm6638a4.htm?s_cid=mm6638a4_e
Notes from the Field: Outbreak of Campylobacter jejuni Associated with Consuming Undercooked Chicken Liver Mousse — Clark County, Washington, 2016
Weekly / September 29, 2017 / 66(38);1027
Derel Glashower, MPH1; Jennifer Snyder1; Diane Welch, MS1; Shannon McCarthy1 (View author affiliations)
View suggested citation

Raw Chicken Juice - Understanding the Risk for Foodborne Illness from Campylobacter

Do people understand the risk when opening that package of raw chicken breasts?  Are they concerned about safe handling of the packaging material and the associated raw chicken juice (or more technically, the exudate)?  Maybe not as much as they should.

A recent study looked at the prevalence of Campylobacter, one of the leading causes of sporadic diarrheal illness in the US, within the package as well as on the outside of the package.  They found that Campylobacter was present in the chicken juice in 60% of packages where the chicken juice was tested.   As for the packaging, none of the outer surfaces had Campylobacter, except for one of the packages that was leaking.

Campylobacter is a commonly found on raw chicken, found on the surface of both skin-on and skin-off chicken, whether parts or whole.  Within the package, it can be found in the juice that comes off the bird, the surface of the bird, and the inner packaging.  Because of this, it is important that consumers not only properly handle the chicken meat, but also the packaging and any dripping chicken juice from the bird or the package.  Drops of chicken juice should be cleaned properly as you go.   Of course, handwashing is critical after handling the meat and the package.   It is also important to purchase packages that are not leaking and to make sure that the less-than-attentive store clerk bags the raw chicken separate from the other foods (in plastic).

Since chicken juice is clear, unlike exudate from red meat which is red in color, drops are more easily missed, or perhaps, not given the same attention.  However from a pathogen standpoint, this research shows that there is a high risk level for pathogen contamination in that chicken juice.

Detection of Campylobacter on the Outer Surface of Retail Broiler Chicken Meat Packages and on Product Within 
Food Protection Trends, vol. 36, no. 3, pp. 176-182, May 2016
Volume 36, Issue 3: Pages 176–182
https://www.foodprotection.org/publications/food-protection-trends/archive/2016-05-detection-of-campylobacter-on-the-outer-surface-of-retail-broiler-chicken-meat-packages-and-/

Linkage of the level of pathogens at farm level to the level at processing

In a recent study, researchers found that pathogen level at the farm level impacted the level of pathogens found in the processing plant, that is, the more pathogens at the farm, the more that were found in the plant. While this is not surprising, it points to the need for added control at the farm level. Unfortunately, there is still a disconnect for some on the impact of farms on downstream contamination issues. While total elimination of pathogens at the farm would unfeasible, a reduction of the level may be achieved through the adoption of improved practices.

Investigators Link Poultry Contamination on Farm and at Processing Plant

CONTACT: Jim Sliwa ASM Newsroom
http://www.asm.org/index.php/asm-newsroom2/88-news-room/journal-tipsheets/91694-investigators-link-poultry-contamination-on-farm-and-at-processing-plant

WASHINGTON, DC – May 31, 2013 -- Researchers at the University of Georgia, Athens, have identified a strong link between the prevalence and load of certain food-borne pathogens on poultry farms, and later downstream at the processing plant. They report their findings in a manuscript published ahead of print in the journal Applied and Environmental Microbiology.

“This study suggests that reducing foodborne pathogen loads on broiler chicken farms would help to reduce pathogen loads at processing, and may ultimately help to reduce the risk of foodborne illness,” says Roy Berghaus, an author on the study. “This is important because most of our efforts towards reducing foodborne pathogens are currently focused on what happens during processing. Processing interventions are effective but they can only do so much.”

Salmonella and Campylobacter bacteria cause an estimated 1.9 million food-borne illnesses in the US annually, and poultry is a major source of both. Earlier studies have linked pathogen prevalence on the farm and at processing, but none has measured the strength of the associations between pathogen loads, according to the report. In the current study, Salmonella and Campylobacter detected at the processing plant were found in farm samples 96 and 71 percent of the time, respectively.

The prevalence of both pathogens dropped during processing, Salmonella from 45.9 percent to 2.4 percent, and Campylobacter from 68.7 to 43.6 percent, according to the report.

The two pathogens are major contributors to human misery in the US. Among 104 different pathogen-food combinations, Campylobacter and Salmonella infections from poultry were recently ranked first and fourth, respectively in terms of “combined impact on the total cost of illness and loss of quality-adjusted life years,” according to the report.

The team suggests that fewer pathogens on the farm would reduce contamination levels at the processing plant, and notes that “vaccination of breeder hens, competitive exclusion products and the use of acidified water during feed withdrawal” have all reduced Salmonella in commercial broiler flocks. However “reliable approaches to reduce Campylobacter colonization are currently unavailable,” although post-processing freezing has reduced Campylobacter loads on carcasses.

A copy of the manuscript can be found online at http://bit.ly/asmtip0513a. The paper is scheduled to be formally published in the June 2013 issue of Applied and Environmental Microbiology.

(R.D. Berghaus, S.G. Thayer, B.F. Law, R.M. Mild, C.L. Hofacre, and R.S. Singer, 2013. Enumeration of Salmonella and Campylobacter spp. in environmental farm samples and processing plant carcass rinses from commercial broiler chicken flocks. Appl. Environ. Microbiol. published ahead of print 26 April 2013 ,doi:10.1128/AEM.00836-13.)

Raw Milk Testing Requirements - Outbeak of Campylobacter in Family Cow Raw Milk

In a recent report (below), there are now 77 cases of campylobacterosis from the consumption of raw milk associated with Family Cow.  What standards are in place for a dairy to sell raw milk?  Attached is the section on testing schedule from Pennsylvania's guidenance for those selling raw milk.  Note that there is no requirement for continuous testing.  In general, APC, coliform, and somatic cell counts are required twice per month and these parameters serve as indicators of sanitary quality,  However, actual pathogen testing is only required once every six months.  Now, dairies selling raw milk may be testing  more frequently.  Probably a good question for the producer of your raw milk.

Raw Milk Testing Standards
Guideance -
PERMITS ALLOWING THE SALE OF
RAW MILK FOR HUMAN CONSUMPTION
http://www.portal.state.pa.us/portal/server.pt/gateway/PTARGS_0_2_24476_10297_0_43/AgWebsite/Files/Publications/Draft_-_Revision_of_Raw_Milk_Guidance_Doc_Final.pdf
9. Regular Testing of Raw Milk.
a.  Responsibility. A raw milk permit holder is responsible to arrange for the regular sampling and testing required with respect to the raw milk permit, and to pay for this testing.

9b. 
Pennsylvania Approved Dairy Laboratories. All raw milk samples submitted for testing must be analyzed at an official laboratory (a laboratory which is under the direct supervision of the Department) or a  Pennsylvania approved dairy laboratory (a laboratory authorized or designated
by the Department as allowed to perform specific milk testing).
c.  Testing Schedule. A raw milk permit holder must coordinate raw milk testing on the following
schedule, and the raw milk samples must meet the following standards: 

Another illness case linked to The Family Cow's raw milk

http://www.publicopiniononline.com/localnews/ci_19984720

CHAMBERSBURG - The number of cases of sickness linked to The Family Cow raw milk stands at 77 in four states.

Outbreaks in the News this week (2/7/12)

There have been some interesting foodborne illness outbreaks in the news this week (Feb 7, 2012).  Here is a quick summary.

Clostridium perfrigens outbreak due to taco meat served at N.D. basketball game.  How it probably happened - the spore-forming organism survived the heat treatment and then grew in the taco meat when that cooked meat was not held at the proper temperature.  Temperature control of cooked food can be an issue  in venues like this.  Unfortunately, people are not willing to question servers when they receive meat products that are not hot.  People preparing and handling food may not have been trained.

http://www.ksfy.com/story/16689309/clostridium-perfringens-cause-of-pierre-outbreak

Watermelon the likely source for Salmonella outbreak – Over 35 people became ill (it occurred in England, so they became unwell) from eating ready-to-eat (pre-sliced) watermelon.  How it probably happened - during the watermelon slicing operation Salmonella was transferred from the outer surface to the interior surface.  This Salmonella could have originated on the raw fruit, and then been spread through the wash water.  If the sliced water melon was not refrigerated, Salmonella could grow on the more pH neutral fruit, making the situation worse.

http://www.telegraph.co.uk/news/uknews/9056645/One-person-dies-after-salmonella-outbreak-linked-to-watermelons.html

Update – Outbreak of Campylobacter from consumption of contaminated raw milk affects 43 people in 4 states.  The dairy has resumed sales. (That raw milk group is a dedicated bunch).

http://www.therecordherald.com/news/x962217783/Raw-milk-sales-resume-at-The-Family-Cow-in-Chambersburg

3 cruise ships disinfected after norovirus outbreak

http://www.washingtonpost.com/lifestyle/travel/ship-with-stomach-virus-outbreak-sets-sail-from-port-everglades-with-new-passengers/2012/02/06/gIQAc8aztQ_story.html?tid=pm_lifestyle_pop

Raw Milk and Campylobacter - Outbreak in PA

There are now close to 40 cases of Campylobacteriosis related to raw milk sold by a Pennsylvania dairy (Franklin County). Although the Campylobacter bacteria has been isolated from bottles of the milk, proponents march on in defense of raw milk – either denying it was the milk, or claiming their right to drink raw milk (read comment on the bottom of page by an advocate).

Campylobacter is a very serious illness. From the CDC (http://www.cdc.gov/nczved/divisions/dfbmd/diseases/campylobacter/):
Campylobacteriosis is an infectious disease caused by bacteria of the genus Campylobacter. Most people who become ill with campylobacteriosis get diarrhea, cramping, abdominal pain, and fever within two to five days after exposure to the organism. The diarrhea may be bloody and can be accompanied by nausea and vomiting. The illness typically lasts one week. Some infected persons do not have any symptoms. In persons with compromised immune systems, Campylobacter occasionally spreads to the bloodstream and causes a serious life-threatening infection.
I believe that people do have the right to drink raw milk, eat raw eggs, and eat raw oysters. But, people need to understand the real risk associated with these products AND society should not pick up the cost once they become sick, or perhaps even ensuring compliance of raw milk producers (that should be built into the cost of product).

Number of people with illnesses linked to raw milk rising in Pa., Md. W.Va.
Lab tests confirm bacteria's presence in raw milk from Chambersburg dairyFebruary 02, 2012|By JENNIFER FITCH | waynesboro@herald-mail.com
 http://articles.herald-mail.com/2012-02-02/news/31019695_1_raw-milk-unpasteurized-milk-dairy-farm