Salmonella Heidelberg: New calf killer in town

Carole Curtis
Salmonella Heidelberg is a fast-moving, multi-drug resistant problem that is killing calves and making people sick.

FT. ATKINSON - Salmonella Heidelberg is an emerging problem in the dairy industry, for both animals and humans.

In August of 2016, a  multidrug resistant S. Heidelberg outbreak was identified in both dairy calves and people in Wisconsin who had contact with ill dairy bull calves.

Of the 106 dairy animal cases of confirmed S. Heidelberg in 2016-2017, 89 were dairy beef calves who had been trucked to a calf raising facility, Dr. Donald Sockett reported during the April Hoard's Dairyman webinar.

The presentation featured a trio of veterinarians: Sockett, Wisconsin Veterinary Diagnostics Lab; Dr. Rachel Klos, Wisconsin Department of Health services; and Dr. Jason Lombard, USDA National Animal Health Monitoring Lab.

The presentation was co-hosted by Abby Bauer, Hoard's Dairyman, and Mike Hutjens, University of Illinois. It was sponsored by Land O Lakes Animal Milk Products Co.

Sockett said the lethal disease hits five to 10 days after a calf arrives, typically  at seven to14 days of age. Death comes quickly. A seemingly healthy animal will gulp down a good breakfast and be dead by early afternoon from generalized bacteremia/septicemia.

Postmortems may reveal enlarged mesenteric lymph nodes, peritonitis and mild interstitial pneumonia.

Sockett stressed that current dairy best practices will not reduce death loss.

A big problem is proper cleaning and disinfection of affected premises and trucks is hampered by design. Close-up and calving pens, hospital pens, preweaned calf barns and calf feed mixing rooms have inadequate sanitary design, he said.

There is also a lack of industry knowledge on proper cleaning and disinfection.

In affected herds, proper cleaning using low pressure foam and disinfection with the correct contact time and concentration is obligatory in high risk areas, Sockett said. The job can be verified with an ATP meter.

Samples taken from calf areas months after diagnosis have tested positive for S. Heidelberg, suggesting the disease is not easily eliminated.

The human side

According to Dr. Rachel Klos, the 2016  public health investigation of the S. Heidelberg outbreak found 18 confirmed human cases between October 2015 - October 2017, peaking in the summer of 2016. Eight were children less than 10 years old, including three infants less than one year old. Seven people were hospitalized; all survived.

The outbreak spread. Between January 2015 and November 2017, 56 people across 15 states were sickened with S. Heidelberg, with 17 people hospitalized. 

In 63 percent of the cases, contact with dairy calves was reported. Traceback showed that most of the calves originated in Wisconsin.

S. Heidelberg is a zoonotic disease, Klos explained, meaning it can be spread between animals and people.

In humans, Salmonella is a bacterial infection that can spark diarrhea, fever and abdominal cramps, and can cause bloodstream infections. Treatment options for S. Heidelberg are limited in people, Klos noted.


Klos recommends small children be supervised during any animal encounter and behaviors that can increase their risk of illness discouraged, such as helping care for sick calves and eating or drinking in areas where livestock are present.

Everyone should always wash their hands thoroughly with soap and water after touching or working with livestock, handling any equipment used on animals, or coming into contact with anything in the animal area.

Use separate shoes, work gloves and clothing when working with livestock.

On-farm study results

Dr. Jason Lombard reported preliminary results from an ongoing multiple agency study of Wisconsin dairy operations. The investigation aims to find the sources of S. Heidelberg, the practices involved in its spread, and what can be implemented to control it.

The on-farm investigation shows S. Heidelberg is fairly widely distributed across Wisconsin. "It is present in all the dairy areas," Lombard observed.

Twenty-one Wisconsin dairy farms of various sizes are participating in the investigation, which involves comparisons of select practices for cases and controls, and testing samples from boot-cover swabs and Swiffer wipes.

The boot swabs and wipes do well for finding S. Heidelberg on an operation.

"The booties detected S. Heidelberg if present in any other sample," Lombard said. "That means workers are likely spreading the disease on the operation."

Preliminary results show the size of the operation makes no difference, but 100 percent of the farms dealing with S. Heidelberg had added cattle, and those with the higher percentages of cases had brought in at least 100 percent of their calves.

"It appears more cattle brought in increases the risk," Lombard observed.

Sourcing calves from dealers and markets is also a factor. When young calves are mixed together and transported, "what you essentially end up with is transfer from calf to calf in a stressful situation," Lombard said.

The distance a calf is transported is also critical, as is the temperature and time in transport, which can lead to increases in shedding, exposure and stress.