Don’t Kiss the Calves

( Maureen Hanson )

Despite your best efforts to keep them healthy, young dairy calves can get sick. Unfortunately, they also can make you sick. And you can even make them sick.

Jeff Bender, DVM, MS, DACVPM shared his insights on zoonotic diseases in a recent edition of the “Dairy Signal,” produced by the Professional Dairy Producers of Wisconsin. Bender works in both the veterinary and public health arenas as Co-Director of the Upper Midwest Agricultural Safety and Health Center (UMASH) based at the University of Minnesota, Minneapolis, Minn.

According to Bender, a zoonotic disease is one that can pass from man to animal, or animal to man. He reported that the U.S. Centers for Disease Control reported 59 disease outbreaks related to animal contact in 2017. Those cases resulted in 1,518 reported illnesses, 312 hospitalizations, and 3 deaths. Of those cases, 25 were linked to farm livestock and 15 to poultry. The rest likely would be attributed to pets, wildlife and/or zoo animals. 

Ongoing disease data tracking at UMASH also shows that agricultural workers are about 8 times more likely to suffer from zoonotic-based enteric disease (gastrointestinal issues and diarrhea) than city dwellers.

The zoonotic disease “biggies” when it comes to raising calves are salmonella, cryptosporidium parvum, campylobacter and E. coli 0157:H7. Calves and older cattle can be “asymptomatic carriers” of these organisms, meaning they have the potential to make people sick, even though they are unaffected. They shed the diseases intermittently in their manure – most frequently in the summer -- which then is inadvertently consumed by humans and then cause disease. 

Bender conducted an interesting study in which he assigned a graduate student to test manure samples from cattle at county fairs throughout Minnesota. They found that 75% of the samples contained E. coli 0157:H7. This is a particularly dangerous zoonotic organism because it causes bloody diarrhea in children, sometimes leading to kidney failure and even death.

Some of these organisms also can be transmitted to humans via food consumption. “Campylobacter is an especially common culprit in raw, unpasteurized milk consumption,” shared Bender. “It has a low infectious dose, and its highest disease incidence is in children 4 years of age and under.”

While Bender said there is proven truth that people, including children, who work and live on farms have wider immunity to many organisms, efforts still should be taken to ensure that humans to not ingest an overwhelming dose of these organisms. Those measures include:

  1. Promote handwashing – COVID-19 has certainly highlighted this practice, and it’s a good one. Bender said soap, heat and drying all are effective in killing bacterial organisms. Provide access to handwashing and drying to workers and farm visitors. Washing hands as you enter the farm at the start of a shift also is a recommended practice. And be wary of the false security of wearing gloves, as dirty gloves still can be vectors for disease transmission.
  2. Change and wash clothing – Dedicated coveralls and boots for working with the calves can keep disease organisms confined to that area. Be especially mindful about removing work clothing and boots before leaving the farm. Provide a convenient way for workers to do this so they can avoid taking organisms into their homes.
  3. Provide a dedicated break area – Do your workers have a place where they can remove their boots and coveralls and wash their hands before they eat? Give thought to this location, for both the comfort and safety of your workers.
  4. Provide effective training – Inform workers of the “invisible” hazards of working with animals via training that is best suited to them. That may be in video format, and might require language translation.

“The dairy industry could benefit from adopting many of the biosecurity practices employed by pork and poultry producers,” noted Bender. “Our people need to be informed about practices that will not just protect their physical safety, but their enteric safety as well.”