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Reconsider planting a kiss on that farm animal

Colleen Kottke
Wisconsin State Farmer
While children and other farm visitors are attracted to adorable farm critters, it isn't wise to risk transmission of disease via close contact.

Encouraging young children to plant a wet kiss on that adorable farm animal is just a bad idea, according to Dr. Jeff Bender, noting that many diseases can be transmitted from animals to human.

Bender, a veterinarian and director of the Upper Midwest Agricultural Safety and Health Center at the University of Minnesota, discussed zoonotic diseases commonly found on dairy farms, how they are transmitted and what farmers and workers can do to protect themselves and their herd from getting infected. Bender shared the information during a Dairy Signal series podcast presented by the Dairy Producers of Wisconsin.

"When we think about risks on dairy farms we think of someone working around an auger, chemical hazards...tractor rollovers and grain bin issues," Bender said. "Other areas that we don't talk about are infectious diseases transferred between animals and humans. COVID reminded us of the impact of the spread of disease."

According to a review of outbreaks associated with animal contact in 2017, the Centers for Disease Control reported there were 59 outbreaks of zoonotic diseases in humans in the US. Bender said over 1518 people became ill with 312 being hospitalized. Of those infected, three died. 

"Over half of those outbreaks were linked to livestock or poultry operations," Bender said. "It reminds us that we are at increased risk due to the environment we work in. The risk to agriculture workers is 8 times that versus someone who doesn't work in that environment."

Bender said four common enteric zoonotic pathogens found on farms particularly among calves include Salmonella, Campylobacter, Crypotosporidium parvum and E. coli 0157. He noted that hand-to-mouth transmission is the primary route of infection, with the infection dose being very low.

Bender referred to an outbreak of salmonella back in 2018 across 15 states that was linked to dairy bull calves. Of the reported 56 human cases, nearly one-third were hospitalized. He noted that the bacteria isolates were drug resistant.

"Here was in issue of antibiotic resistance and it was a disease that was spilling over from the calves who had salmonella that was killing them...and infecting the people working with those calves," Bender said.

He pointed out that chickens may also carry salmonella, putting backyard chicken owners at risk.

"They're cute and kids like them and will snuggle the baby birds, putting them up to their mouthes and kissing them. It can be a real problem for children and the immuno-compromised," he said.

Bender says that campylobacter is highly infectious in children less than a year of age, and can cause severe diarrhea. It has a low infectious dose level, with many outbreaks attributed to drinking raw milk.

An E. coli 0157 infection in children can result in bloody stools and kidney failure, and may be fatal to those ages 5 and younger. Bender recalled an outbreak in 2013 where many children became infected from petting young steers in a petting zoo at a pumpkin patch. 

He noted that many animals carry the pathogen without exhibiting any outward signs of infection. However, the animals can be shedding the bacteria without handlers even realizing it.

He pointed to a study done in Minnesota back in 2006 where manure samples were collected from the calves exhibited at several county fairs across the state. 

"Anywhere from 15 to 20% of herds nationwide are actually positive," Bender said. "The tests taken from fairs in mostly dairy-focused counties came back with 75% of the samples testing positive for E. coli."

Bender says that cattle tend to shed the bacteria intermittently, especially when they are young in the pre-weaning stage. Transmission rates also tend to be higher in the summer.

Young children, the elderly and those who may be immunosupressed may be especially vulnerable to becoming infected with a pathogen commonly found on dairy farms.

"It doesn't cause disease in the animal so you don't even know that they have it. So it's an awareness that some folks can be exposed to this unbeknownst to them, especially with the manure," he said. "This is one of the bugs that actually makes me nervous especially with kids on the farm."

Others that may be vulnerable to infection are new workers who has never been on a farm before and are unaware of some of the risks and measures to take to avoid being exposed.

Cryptosporidiosis is also commonly found on farms with cattle serving as a primary reservoir for the pathogen. The pathogen causes significant disease in calves and "doesn't take much to cause illness in people," Bender said.

He said many people who live and work on farms for a long period of time may claim to have developed an immunity to the illnesses.

"We do see with some of these organisms like cryptosporidium in which they've sampled farmers and found some immunity most likely because of their previous exposure," Bender said. "Now is that true for E. coli and capmpylobacter and salmonella? I really don't know."

While some believe that being exposed may help them stay healthier in the long run, Bender cautions ag workers about getting an "overwhelming exposure" to pathogens.

"We work in an environment where there's a lot of poop anyway, so it's important for us to minimize any hand-to-mouth activities or potential because we don't want to take that risk," he said.

Bender says that workers may be lax about the danger of pathogens simply because they don't see them. To prevent becoming infected with these diseases, farm families and workers should practice sound biosecurity measures and good hygiene.

Workers may be lax about the danger of pathogens simply because they don't see them. To prevent becoming infected with these diseases, farm families and workers should practice sound biosecurity measures and good hygiene.

Those working with calves should have a dedicated pair of coveralls and boots that can be changed out of before moving to another area of the farm.

"I usually like to work with the younger animals first before moving on to the older ones," Bender said. "There should also be good separation between the younger and older animals."

He said workers should looking at gloves as a "panacea" to becoming infected.

"Those gloves get dirty and contaminated and if you decide to smoke and touch your face..." he added. 

It's also important to do a thorough job when cleaning equipment, bottles, pails and nipples to prevent the spread of disease.Employees should also take care to wash their hands before and after working with animals. Those instructions and expectations should translated to workers through training or in materials translated into appropriate languages.

He said farm owners should also take a critical look at the breakroom where employees eat.

"I like to see how clean it is and where it is located; is it next to the animal holding areas? Are we providing places for folks to be able to wash their hands and remove their boots and coveralls before eating?" he said. "It's important to create a safe work environment but if the refrigerator never gets cleaned or there's manure on the door handle, then we need to be thinking about creating some of those protections."