CDC Outbreak Variances by Location and Serovar

  1. Serotype Typhi, for example, is known to exist only in humans, serotype Choleraesuis has a primary reservoir in pigs, and serotype Dublin in cattle 
  2. Serotype IV 48:g,z51:− causes sporadic illness from contact with the environment of a marine iguana, the serotype’s only known host
  3. Counts for serotypes I,4,[5],12:i:− and Typhimurium (including Typhimurium var. 5-) were combined (and labeled Typhimurium+) because not all state laboratories could make the distinction. 
  4. CVs for 37 serotypes examined by state, month, age group, and sex are shown in S1 Table. The serotypes with the most evenly distributed rates across all states and regions were Typhimurium+ (CV 30%), Infantis (CV 40%), and Heidelberg (CV 33%). At the other end of the spectrum, serotypes Mississippi (CV 256%), Rubislaw (CV 197%), and Give (CV 195%) were heavily concentrated in the Gulf Coast states. Other serotypes that showed geographic concentration included Norwich (CV 161%), being reported mostly from the lower Midwest into the South, and Javiana (CV 135%), also most frequently reported from the South.
  5. Serotypes with the largest CVs by month were Norwich (CV 87%), Javiana (CV 83%), Mississippi (CV 69%), and Newport (CV 68%). All were highly concentrated in months that are generally warmer in the US, averaging 45% of reported isolates of these four serotypes (range, 41% to 47%) in summer (June-Aug) and 8% (range, 7% to 11%) in winter (Dec-Feb). Conversely, serotypes Senftenberg, Mbandaka, Anatum, and Derby had low CVs by month (18%, 21%, 24%, and 24% respectively), indicating that isolations occurred fairly evenly throughout the year, with an average of 30% (range, 28% to 31%) of isolates reported in summer and 22% (range, 20% to 26%) in winter.
  6. The variation in incidence rate by age was highest in serotypes Rubislaw (CV 265%), Mississippi (CV 160%), Poona (CV 151%), and Schwarzengrund (CV 150%)—all found mostly in young children. Enteritidis (CV 24%), Berta (CV 40%), and Braenderup (CV 41%) were the serotypes most equally distributed by age. The rate was highest among young children for 34 of the 37 common serotypes; the exceptions were Senftenberg (highest rates among adults aged 70 years and older), Paratyphi A (highest rates among 20- to 34-year-olds), and Tennessee (highest rate among adults aged ≥74 years).
  7. Serotypes with higher variation in incidence by age group (ie, skewed toward particular ages) were more common among males (Spearman’s correlation p <0.01) and had higher incidence variation by state (p <0.01). There was no correlation between variation by age and season (p = 0.13), sex and season (p = 0.74), or sex and region (p = 0.36). Serotypes whose incidence increased the most in the second half of the 16-year study period had higher incidence variation by season (Spearman’s correlation p <0.01) and by state (p = .02). Changes in incidence did not correlate with variation by age or sex.
  9. (this document lists a couple of serovars and their direct affiliations with dogs, but they are interspersed and not, therefore, copied here). The magnitude of this reservoir may be considerable; a survey conducted by Galton et at. (4) revealed 27.6% of 8,157 rectal swabs, collected from dogs, were positive for Salmonella. Dogs, on occasion, have been observed to eat carrion and garbage and to practice coprophagy. Therefore, the mechanism for transmission of Salmonella to dogs, and re-infection among dogs, may be present continually.
  10. Dried dog foods were incriminated as the source of Salmonella infections among colonies of laboratory animals as early as 1952. (5)
  11. Bacteriological examination of a portion, approximately 44 g, of commercial dried dog food, obtained January 24, 1976, from a supply at the home of the index case, yielded isolates of S. enteriditis serotypes lnfantis and Minnesota.
  12. Sampling and testing plans for Salmonella, as employed by the Food and Drug Administration (FDA), have been described (9). It would be prudent for the dried dog food industry to consider adopting the FDA sampling recommendation for foods in Category I.
  13. It is abundantly clear that dogs, infected with Salmonella, can provide a link in disease transmission to humans (7). Therefore, manufacturers of dried dog food should be interested in adopting more stringent laboratory testing to provide evidence that their products present a low consumer risk.
  14. As many as nine serotypes were detected in a single sample. These products were allegedly produced by an expansion extrusion process. It is reasonable to SALMONELLAE IN DOG FOOD 321 consider this a critical control point in production of dried dog food; time, temperature, and moisture parameters lend themselves to continual monitoring for quality control. Methods to eliminate the hazard of post-processing contamination, if it exists, might well be investigated. The possibility that dried dog foods may provide a vehicle to introduce Salmonella into the home is not sufficiently recognized by consumers. This investigation has brought forth the following questions: (a) Is it realistic to expect manufacturers to produce Salmonella-free dried dog food? (b) Should the answer to the first question be negative, what degree of hazard does dried dog food present to pets and to their owners? (c) Should pet owners be cautioned about the handling, storage, and potential for abuse of dried dog foods?

Recommending against commercially available raw (rather than co-op and grocery) decreases FDA credibility because FDA is tasked with monitoring safety of these products yet they publicly state that they are unsafe to use

Raw food trials with pets:!po=0.431034 “Little evidence also exists on the significance of raw meat feeding on the shedding of CampylobacterSalmonella, and enteropathogenic Yersinia in the feces of pets.”

Results (3): Enteric pathogens were detected in 28% of the RMBDs, originating from 12 producers… Salmonella was detected in only 2% of the samples…”

Discussion (4): Salmonella was rarely detected in our study and the occurrence (2% by PCR and <1% by culturing) was clearly lower than reported in Canada and USA.

Conclusions (5): These pathogens were not found by culturing, indicating a low contamination level in frozen commercial RMBDs produced in Finland. Salmonella and enteropathoenic Yersinia were detected only in dogs fed RMBDs: however, the infection source and transmission routes remained unclear.

The Hardt Lab – Salmonella Pathogenesis, Institute of Microbiology, ETH Zurich – (research Salmonella shedding from humans)

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