Global & Disaster Medicine

Multistate Outbreak of Multidrug-Resistant Salmonella Heidelberg Infections Linked to Contact with Dairy Calves

CDC

Since the last update on August 2, 2017, eight more ill people have been reported from six states.

People infected with the outbreak strain of Salmonella Heidelberg, by state of residence, as of October 30, 2017

  • CDC, several states, and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS) are investigating a multistate outbreak of multidrug-resistant Salmonella Heidelberg infections.
  • A total of 54 people infected with the outbreak strains of Salmonella Heidelberg have been reported from 15 states.
    • Seventeen (35%) people have been hospitalized. No deaths have been reported.
    • Illnesses started on dates ranging from January 27, 2015 to October 15, 2017.
    • Eighteen (33%) people in this outbreak are children under the age of 5.
  • Epidemiologic and laboratory investigations linked ill people in this outbreak to contact with calves, including dairy calves.
    • In interviews, ill people answered questions about contact with animals and foods eaten in the week before becoming ill. Of the 54 people interviewed, 34 (63%) reported contact with dairy calves or other cattle. Some of the ill people interviewed reported that they became sick after their dairy calves became sick or died.
    • Ongoing surveillance in veterinary diagnostic laboratories showed that calves in several states continue to get sick with the outbreak strains of multidrug resistant Salmonella Heidelberg. ‎
    • Information collected earlier in the outbreak indicated that most of the calves came from Wisconsin. Regulatory officials in several states are now tracing the origin of the calves that are linked to the newer illnesses.
  • Antibiotic resistance testing(https://www.cdc.gov/narms/resources/glossary.html) conducted by CDC on clinical isolates from ill people shows that the isolates were resistant to multiple types of antibiotics.
    • Antibiotic resistance may be associated with increased risk of hospitalization, development of a bloodstream infection, or treatment failure in patients.
    • Whole genome sequencing has identified multiple antimicrobial resistance genes in outbreak-associated isolates from 43 ill people, 87 isolates from cattle, and 11 isolates from animal environments.
    • These findings match results from standard antibiotic resistance testing(https://www.cdc.gov/narms/resources/glossary.html) methods used by CDC’s National Antimicrobial Resistance Monitoring System (NARMS)(https://www.cdc.gov/narms/index.html) laboratory on clinical isolates from eight ill people in this outbreak.
    • All eight isolates from ill people were resistant to amoxicillin-clavulanic acid, ampicillin, cefoxitin, ceftriaxone, streptomycin, sulfisoxazole, and tetracycline, and had reduced susceptibility to ciprofloxacin. Seven isolates were also resistant to trimethoprim-sulfamethoxazole. Five were also resistant to nalidixic acid. Three were also resistant to chloramphenicol. All eight isolates tested were susceptible to azithromycin and meropenem.
  • Follow these steps to prevent illness when working with any livestock:
    • Always wash your hands thoroughly with soap and water right after touching livestock, equipment, or anything in the area where animals live and roam. Use dedicated clothes, shoes, and work gloves when working with livestock. Keep and store these items outside of your home.
    • It is especially important to follow these steps if there are children under age 5 in your household. Young children are more likely to get a Salmonella infection because their immune systems are still developing.
    • Work with your veterinarian to keep your animals healthy and prevent diseases.
  • This investigation is ongoing and we will provide updates as more information becomes available. Livestock owners should continue to watch for increased sicknesses in dairy calves and consult their veterinarian if needed.

 


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