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Public Health - Seattle & King County


Salmonella infection is spread through the fecal-oral route, through contaminated food and water, and through direct and indirect contact with infected animals and their environments. Animals commonly infected with Salmonella include reptiles (such as snakes, lizards, and turtles), chickens, ducks, pigs, cows, and rodents. Pets are a common source of infection. Infected children and persons with poor hygiene can contaminate the household environment, leading to household transmission. Persons with salmonellosis can remain infectious even after symptoms resolve and spread infection for several days to weeks and less commonly, for months or years. Salmonella outbreaks have been associated with a variety of commercially distributed food products, including produce, nuts, eggs, and poultry.

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Salmonellosis in King County

Purpose of surveillance:

  • To identify common source outbreaks
  • To identify and eliminate sources of transmission including contaminated food and water

Salmonellosis Case Data in King County

Local epidemiology:

In 2014, 218 laboratory-confirmed and ten epidemiologically-linked cases of salmonellosis were reported. This is comparable to a five-year average of 220 cases per year. Thirty-three cases (14%) were attributed to international travel (12 Asia and South Pacific, 12 Latin America and Caribbean, 4 Middle East, 3 Africa, and 2 Europe). Thirty-nine (17%) cases were hospitalized and none died.

Thirteen cases (6%) reported contact with reptiles, including pet snakes, lizards, bearded dragons and turtles, during their exposure period. Reptiles are frequent carriers of Salmonella bacteria, which often contaminate their skin. Good hand hygiene following contact with reptiles is important. Reptiles are not suitable pets in households with infants and children under the age of five.

One pediatric case was linked a multi-state outbreak involving sprouted chia seed powder. This nutritional additive originated from a Canadian firm and was distributed by multiple companies in products including smoothie mix and nutritional supplements. Three serotypes of Salmonella were linked to this outbreak, and multiple product samples (including one contributed by the King County case) tested positive for strains of Salmonella indistinguishable from those isolated from patients.

Twenty-two confirmed and four probable cases of salmonellosis were associated with an outbreak related to custom slaughter specialty meats. An additional fourteen cases were identified in five neighboring counties. An intensive investigation involving state and local health departments, environmental health teams, and state and federal regulators was conducted into the numerous processes involved in custom slaughter retail. Environmental samples collected from four locations in multiple counties matched two of three Salmonella strains isolated from the cases. Several cases in this outbreak reported consuming East African dishes which included raw or undercooked beef. It is important to cook meats to an appropriate internal temperature (see the FDA Food Safety and Inspection Service (FSIS) page for additional details), as it is impossible to tell from sight or smell whether they are infected with bacteria like Salmonella.

Each year in Washington state between 650 and 850 cases are reported, of which roughly 200 to 300 are in King County. Since 2004, "genetic fingerprinting" of Salmonella isolates has facilitated the identification of cases linked to nationwide outbreaks.