The multi-state outbreak of multi-drug-resistant Salmonella Heidelberg infections that was linked to contact with dairy bull calves is over.
Since its last update Nov. 28, the federal Centers for Disease Control and Prevention reports an additional 15 confirmed cases were added to the outbreak. Five of those required hospitalization.
Final counts for the outbreak are 36 confirmed cases with 13 hospitalizations. There have not been any deaths associated with the multi-drug-resistant Salmonella Heidelberg infections.
The outbreak had a 10-state footprint with the addition of Texas and North Dakota since November.
In the final report Monday, CDC again warned about contact with livestock especially by handlers and veterinarians. It issued advice to those groups.
Through epidemiology, laboratory and traceback investigations, CDC has linked this outbreak with sick calves, including dairy bull calves, that were purchased from livestock markets in Wisconsin.
“In interviews, ill people answered questions about any contact with animals and foods eaten in the week before becoming ill. Of the 36 people interviewed, 25 (69 percent) reported contact with dairy bull calves or other cattle, the final report says. “Some of the ill people interviewed reported that they became sick after their dairy bull calves became sick or died.”
“One ill person’s dairy calves were tested for the presence of Salmonella bacteria. This laboratory testing identified Salmonella Heidelberg. Additionally, environmental samples were collected from a livestock market in Wisconsin, and these samples also identified Salmonella Heidelberg,” it continued.
“Further testing using WGS showed that isolates from ill people were closely related genetically to both the isolates from these calves and to the livestock market. This close genetic relationship means that the human infections in this outbreak were likely linked to sick calves.”
Dairy bull calves are young, male cattle that may be raised for meat.
CDC’s final report said multidrug-resistant infections are harder to treat and have been associated with higher risk of hospitalization and bloodstream infections. The agency said health care providers should be aware that many antibiotics typically used to treat Salmonella infection aren’t effective against this multidrug-resistant strain.
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