What are the most common sources of Salmonella bacteria?

Most Common Sources of Salmonella Bacteria

The most common sources of Salmonella bacteria include poultry and poultry products, reptiles, amphibians, rodents, live animals (especially farm animals), contaminated produce, and pet food products. 1

Animal Sources

Poultry and Livestock

• Live poultry: Chickens, ducks, turkeys, and geese are significant reservoirs of Salmonella

  • Multiple outbreaks linked to contact with live poultry at feed stores, schools, day cares, fairs, and petting zoos 1
  • At least 14 multistate outbreaks linked with live poultry from mail-order hatcheries were reported between 2005-2010 1

• Farm animals: Cattle and other farm animals are common carriers

  • Contact with farm animals has been documented as a risk factor for sporadic Salmonella infections 1
  • Visiting farms with cows increases risk of infection, especially in children 1

Reptiles and Amphibians

• Turtles and other reptiles: Well-established sources of human Salmonella infections 1

  • Three large multistate outbreaks linked to contact with small turtles (2006-2010), including a fatal case in an infant 1

• Aquatic amphibians: Approximately 200 Salmonella Typhimurium infections were linked to African dwarf frogs during 2009-2011 1

  • Infections occurred through contact at carnivals, nursing homes, day cares, pet stores, and retail stores 1

Rodents and Other Small Animals

• Rodents: Used as pet food or for educational purposes
  • Outbreaks associated with frozen rodents purchased to feed snakes 1
  • Salmonellosis outbreaks linked to dissection of owl pellets in school settings 1

Food Sources

Animal-Derived Foods

• Eggs and poultry products: Traditional and significant sources 2, 3
• Meat products: Pork, beef, and other meats 3, 4
• Pet food and treats:
  • Contaminated dry dog and cat food (79 human infections during 2006-2008) 1
  • Pig ear treats and pet treats containing beef and seafood 1

Produce and Plant-Based Foods

• Fresh produce: Increasingly recognized as sources of Salmonella outbreaks 2
  • Vegetables, fruits, nuts, and flour 5
  • Contamination often occurs through irrigation with contaminated water 2

Aquatic Sources

• Fish and aquariums:
  • Multidrug-resistant Salmonella infections linked to contaminated water from home aquariums with tropical fish 1
  • 22% of surveyed tropical fish tanks in one study yielded potentially pathogenic bacteria 1

Transmission Mechanisms

Environmental Contamination

• Water sources: Contaminated irrigation and washing water for crops 2
• Soil: Contaminated through animal waste or manure 2

Human-to-Human

• Food handlers: Asymptomatic carriers can contaminate food
  • In one outbreak, a food service worker tested positive for two different Salmonella serotypes 1

Cross-Contamination

• Food preparation areas: Inadequate cleaning of contact surfaces 1
• Improper handling: Using food service areas for activities involving potential Salmonella sources 1

High-Risk Settings

• Public animal contact venues: Petting zoos, fairs, educational farms 1
• Schools: Especially when conducting activities with animal products 1
• Healthcare settings: Particularly concerning for immunocompromised patients 1

Prevention Considerations

• Hand hygiene: Scrupulous handwashing after potential contact with animal sources 1
• Proper food handling: Separate preparation areas for different food types
• Education: Awareness of zoonotic disease risks is protective against illness in outbreaks 1

Special Populations at Risk

• Immunocompromised individuals: Higher risk for severe disease and bacteremia 1
• Children: More susceptible to infection from animal contact 1
• Elderly: Higher risk for severe manifestations of infection

Understanding these common sources of Salmonella is crucial for implementing effective prevention strategies and reducing the burden of salmonellosis.