--- title: Transmission of Salmonella Bacteria date: 2021-01-29T12:04:00-08:00 author: admin canonical_url: "https://marlerclark.com/foodborne-illnesses/salmonella/transmission-of-salmonella-bacteria" section: Resource Library --- [Foodborne Illnesses](/foodborne-illnesses) / [Salmonella](https://marlerclark.com/foodborne-illnesses/salmonella) / # Transmission of Salmonella Bacteria In the past two decades, consumption of produce, especially sprouts, tomatoes, fruits, leafy greens, nuts, and nut butters, has been associated with *Salmonella* illnesses. The surface of fruits and vegetables may be contaminated by human or animal feces. Changes in food consumption and production, as well as the rapid growth of international trade in agricultural products, have facilitated the transmission of *Salmonella* associated with fresh fruits and vegetables. ![](https://s3.us-west-2.amazonaws.com/aboutsalmonellacom-images/outbreaks/image6.jpg)In the United States, *Salmonella* is the second most commonly isolated bacterial pathogen when laboratory diagnosis of diarrhea is sought. However, passive laboratory surveillance, which uses voluntary reporting by health care providers and facilities, captures only a fraction of illnesses that actually occur. Furthermore, only a small proportion of illnesses are confirmed by laboratory testing and reported to public health agencies. Thus, researchers rely on quantitative statistical modeling to estimate the incidence of foodborne illness. These estimates are used to direct policy and interventions. In 2011, Scallan and colleagues published results of a comprehensive study of estimates of the burden of foodborne illness in the United States. Using surveys, study results, and statistical methods, their estimates have provided the most accurate picture yet of which foodborne pathogens (bacteria, viruses, and parasites) cause the most illnesses. Scallan et al. estimate that, each year in the United States, 31 pathogens cause 9.4 million foodborne illnesses. Illnesses caused by consumption of contaminated food result in 55,961 hospitalizations and 1,351 deaths annually. For each nontyphoidal *Salmonella* infection reported, Scallan et al. estimate that there are 29.3 infections that are not diagnosed and/or reported. Thus, foodborne nontyphoidal *Salmonella* spp. account for 1.0 million cases or 11% of the total burden of foodborne illness each year. Nontyphoidal *Salmonella* was estimated to result in 19,336 hospitalizations each year, making it the leading cause of hospitalizations attributed to contaminated food eaten each year in the United States. Foodborne nontyphoidal *Salmonella* was estimated to result in 378 deaths each year. The CDC Foodborne Disease Outbreak Surveillance System (FDOSS) collects data on foodborne disease outbreaks, using a web based platform, [the National Outbreak Reporting System or NORS](http://www.cdc.gov/nors/). *Salmonella* was the most commonly reported agent for all bacteria associated outbreaks reported to NORS in 2017. That year, there were 122 *Salmonella* outbreaks (113 laboratory-confirmed and nine suspected). *Salmonella* caused the most outbreak-associated hospitalizations (472 hospitalizations). Eight outbreak-associated deaths were reported. Twenty of the 32 multistate outbreaks with the first identified illness occurring in 2017 were caused by *Salmonella*. The most frequent serotypes were *S.* Newport (three outbreaks) and *S*. Braenderup (two outbreaks). There were an additional 10 multistate *Salmonella* outbreaks investigated in 2017 but not included in the tally for 2017, as the first illnesses occurred in 2016. The food sources in the 2017 multistate *Salmonella* outbreaks were coconut (three outbreaks), papaya (three outbreaks), chicken, eggs, kratom powder, melon, raw sushi, and sprouts. Leafy greens, mango, Mexican-style cheese, papaya, romaine lettuce, and watermelon were suspected sources. A food was not identified for two outbreaks caused by *Salmonella*. Implicated foods in 10 outbreaks investigated in 2017—but with illnesses beginning prior to 2017—include chicken, ground beef, and papaya. Foodborne illness outbreak data from previous years support these findings. During 2009-2015, FDOSS received reports of 5,760 outbreaks. Among 2,953 outbreaks with a single confirmed etiology, *Salmonella* was the second most common cause of outbreaks. For the seven-year period, there were 896 *Salmonella* outbreaks and 23,662 associated illnesses. The largest of the 177 multistate outbreaks was caused by *Salmonella* serotype Enteritidis associated with contaminated shell eggs. An estimated 1,939 persons were infected in 10 states beginning in 2010. A multistate outbreak of *Salmonella* Poona infections attributed to cucumbers in 2015 had the second highest number of illnesses (907 illnesses in 40 states). This outbreak also had the most outbreak-associated hospitalizations (204, or 22% of cases). Human *Salmonella* infections associated with indirect or direct contact with animals have emerged as an important public health problem. *Salmonella* is found in the intestinal tract of many animals including reptiles, amphibians, and live poultry such as chicks, chickens, ducklings, ducks, geese, and turkeys. Although the majority of *Salmonella* infections are foodborne, about 3% are acquired through indirect and direct contact with animals, making it an important public health problem. Indirect transmission occurs through contact with things in areas where animals live and roam, or consumption of food/drink prepared in contaminated environments. In recent years, numerous outbreaks of *Salmonella* infections in humans have been linked to contact with live poultry in both household and public settings. Live poultry infected with *Salmonella* appear healthy, but can intermittently shed bacteria. An increase in backyard flock ownership in the United States has likely contributed to the rise in live poultry-associated salmonellosis. Large outbreaks occur almost annually. From 1996 to 2012, 45 outbreaks of human *Salmonella* infections linked to live poultry were documented. These outbreaks resulted in more than 1,581 illnesses, 221 hospitalizations, and five deaths. Because of unreported infections, many more illnesses likely occurred in these outbreaks. Multiple *Salmonella* serotypes were identified, and specific outbreak strains were repeatedly linked to individual mail-order hatcheries over multiple years. From 2013 to 2019, multiple outbreaks were investigated with illnesses occurring in every state. ![](https://s3.us-west-2.amazonaws.com/aboutboutlismcom-images/t3salm.PNG)Owners and caretakers of backyard poultry should always wash their hands thoroughly with soap and water right after touching live poultry or anything in the area where they live and roam. Adults should supervise hand washing for young children. [CDC provides guidelines for safely keeping backyard poultry.](https://www.cdc.gov/healthypets/pets/farm-animals/backyard-poultry.html) Other animals such as reptiles, amphibians, and household pets have also been associated with transmission of *Salmonella* to humans. Proper handwashing will help reduce the risk of getting sick from bacteria that pets can carry. [More information can be found here.](https://www.cdc.gov/healthypets/health-benefits/index.html) Direct person-to-person contact, nosocomial transmission, waterborne transmission, and contaminated drugs and solutions are important but less common modes of transmission for human *Salmonella* infections. [ Next: Symptoms of Salmonella Infection › ](https://marlerclark.com/foodborne-illnesses/salmonella/salmonella-symptoms-risks) ### More information about Salmonella [December 30, 2022 ###### FDA weighs in on Sun Sprouts Salmonella Outbreak The U.S. Food and Drug Administration (FDA), along with the Centers for Disease Control and Prevention (CDC) and state and local partners, is investigating a multistate outbreak of Salmonella Typhimurium ... ](https://marlerclark.com/news_events/fda-weighs-in-on-sun-sprouts-salmonella-outbreak) [December 11, 2022 ###### 4 Restaurant Chains That Have Had Salmonella Outbreaks In late June of 2003, the Lake County Health Department (LCHD) was contacted by health care providers who had treated patients for Salmonellosis, and customers who had experienced a diarrheal ... ](https://marlerclark.com/news_events/4-restaurant-chains-that-have-had-salmonella-outbreaks) [October 23, 2022 ###### Raw Fish is Salmonella Risk in California and Arizona ... ](https://marlerclark.com/news_events/raw-fish-is-salmonella-risk-in-california-and-arizona) [September 27, 2022 ###### Andrew & Williamson Fresh Produce Cucumber Outbreak Marler Clark, the Salmonella Lawyers, filed 12 lawsuits and were retained by over two dozen families. As of October 14, 2015, 71 more ill people were reported from 23 states ... ](https://marlerclark.com/news_events/andrew-williamson-fresh-produce-cucumber-outbreak) [1. View all ](/news_events/outbreaks?illness=salmonella&year=all) ## All Salmonella Resources [###### Salmonella Food Poisoning ](https://marlerclark.com/foodborne-illnesses/salmonella/about-salmonella) [###### The Incidence of Salmonella Infections ](https://marlerclark.com/foodborne-illnesses/salmonella/the-incidence-of-salmonella-infections) [###### The Prevalence of Salmonella in Food and Elsewhere ](https://marlerclark.com/foodborne-illnesses/salmonella/the-prevalence-of-salmonella-in-food-and-elsewhere) [###### Transmission of Salmonella Bacteria ](https://marlerclark.com/foodborne-illnesses/salmonella/transmission-of-salmonella-bacteria) [###### Symptoms of Salmonella Infection ](https://marlerclark.com/foodborne-illnesses/salmonella/salmonella-symptoms-risks) [###### Complications of Salmonella Infection ](https://marlerclark.com/foodborne-illnesses/salmonella/complications-of-salmonella-infection) [###### How is Salmonella Infection Diagnosed? ](https://marlerclark.com/foodborne-illnesses/salmonella/salmonella-diagnosis) [###### Treatment for Salmonella Infection ](https://marlerclark.com/foodborne-illnesses/salmonella/salmonella-treatment) [###### Antimicrobial Resistance ](https://marlerclark.com/foodborne-illnesses/salmonella/antibiotic-resistance) [###### The Economic Impact of Salmonella Infections ](https://marlerclark.com/foodborne-illnesses/salmonella/the-economic-impact-of-salmonella-infections) [###### Real Life Impacts of Salmonella Infection ](https://marlerclark.com/foodborne-illnesses/salmonella/real-life-impacts-of-salmonella-infection) [###### How to Prevent a Salmonella Infection ](https://marlerclark.com/foodborne-illnesses/salmonella/salmonella-prevention) [###### Salmonella Outbreaks ](https://marlerclark.com/foodborne-illnesses/salmonella/salmonella-outbreaks) [###### Salmonella Outbreak at Minnesota Chipotle Sickens 64 People ](https://marlerclark.com/foodborne-illnesses/salmonella/salmonella-outbreak-at-minnesota-chipotle-sickens-64-people) [###### Citterio Salame Stick Oubreak ](https://marlerclark.com/foodborne-illnesses/salmonella/citterio-salame-stick-oubreak) [###### Salmonella Recalls ](https://marlerclark.com/foodborne-illnesses/salmonella/salmonella-recalls) ### Other foodborne illnesses [E. coli](https://marlerclark.com/foodborne-illnesses/e-coli) [Listeria](https://marlerclark.com/foodborne-illnesses/listeria) [Hepatitis A](https://marlerclark.com/foodborne-illnesses/hepatitis-a) [Reactive Arthritis](https://marlerclark.com/foodborne-illnesses/reactive-arthritis) [Guillain-Barre Syndrome](https://marlerclark.com/foodborne-illnesses/guillain-barre-syndrome) [Irritable Bowel Syndrome](https://marlerclark.com/foodborne-illnesses/irritable-bowel-syndrome) [Norovirus](https://marlerclark.com/foodborne-illnesses/norovirus) [Botulism](https://marlerclark.com/foodborne-illnesses/botulism) [Campylobacter](https://marlerclark.com/foodborne-illnesses/campylobacter) [Shigella](https://marlerclark.com/foodborne-illnesses/shigella) [Cyclospora](https://marlerclark.com/foodborne-illnesses/cyclospora) [Hemolytic Uremic Syndrome](https://marlerclark.com/foodborne-illnesses/hemolytic-uremic-syndrome)