This story was originally published in July 2018.
Sometimes in this world, it’s the little things that can cause the most problems. Really, really little things.
This is especially true for anyone working around or with livestock in Maine, according to Dr. Anne Lichtenwalner, director of the University of Maine Veterinary Diagnostic Laboratory and associate professor of animal and veterinary science.
Some farm animals can actually “share” parasites with their human companions.
“There are actually just a handful of parasites that I worry about,” Lichtenwalner said. “These are critters that are parasites that can live inside you and tend not to be fatal, but that can cause some ugly surprises.”
The two most common zoonotic parasites — those that can transfer from animals to humans — in Maine are Ascaris suum and Cryptosporidium.
“You are protected by your innate and acquired immune system,” Lichtenwalner said. “When you are healthy and practice good hygiene there are not too many things that can get you, but you do need to be savvy and protect yourself.”
Pigs and worms
Ascaris suum — or roundworm — is most commonly found in pigs and their manure, according to Lichtenwalner and, as parasites go, has a pretty simple life cycle.
“You eat the egg and it grows into adulthood in your body,” she said. “It can migrate to places like the liver, but it matures as an adult in the small intestine.”
Symptoms of roundworms in humans — or “ascariasis” — include nausea, vomiting, diarrhea, weight loss, abdominal pain and visible worms in the stool. They can also migrate into the lungs and cause coughing or gagging, wheezing, chest discomfort and fever.
According to information in a 2015 online report from the U.S. Centers for Disease Control and Prevention, 14 cases of ascariasis in humans who had contact with pigs were identified in Maine between over the previous five years.
It’s an easy thing to avoid, according to Lichtenwalner.
“Avoid using pig manure as a garden fertilizer,” she said, noting the roundworm eggs can be present in the manure.
If the eggs are in the manure, they can be transferred to a human host by touching. The eggs — which can survive for months in manure-treated soil — can also end up on what is grown in that soil and, if that crop is consumed without first washing it properly, those eggs will transfer to the human host.
“If you have pigs and bought them to clear land and then want to plant on that land, make sure the pigs don’t have roundworm in the first place.”
By checking pigs for the presence of roundworms before bringing them onto a farm or property, you avoid bringing the parasite altogether, she said.
“You avoid feeding the land with this crazy parasite,” Lichtenwalner said. “You want to raise fresh lettuce and other products and you bring in these wonderful pigs and want to turn them loose to fertilize — maybe that is not such a good idea unless you check them first and always [medically] treat them for worms.”
She also stressed thoroughly washing your hands after touching any manure and washing all fresh vegetables before consuming them.
Roundworms are easily treated in pigs and people, and Lichtenwalner said most of the time the biggest issue is the “ick factor” of seeing the actual worms.
The other big trouble maker in Maine is Cryptosporidium, a microscopic parasite that is most often associated with hoofed mammals, such as cattle.
“These guys can live in your GI tract where they set up shop and invite the neighbors over for drinks,” Lichtenwalner said. “When there are enough of them, they make the lining cells of your gut rupture and cause intractable diarrhea.”
Cryptosporidiosis — or “Crypto” — is more difficult to treat than roundworm, she said, and often requires specialized medical attention.
“You have to use the right drugs to clear it up [and] it’s not pleasant,” she added.
According to information on the Maine Centers for Disease Control 2015 Infectious Disease Epidemiology Report published in 2016, there were 34 confirmed cases of Cryptosporidiosis in Maine in 2015.
“Crypto is most happy living in cow poop,” Lichtenwalner said. “So when we use cow manure for compost or fertilizer it can be transmitted with fresh vegetables.”
Cryptosporidiosis is also transmitted in water that has been polluted by manure and can be transmitted to humans by simply touching or petting a cow or other animal which is infected.
“People and especially kids love to pet these sweet animals,” Lichtenwalner said. “But sometimes the front end of that animal touches its back end and picks up the fecal material [and] spreads the parasite to other parts of its body.”
The biggest preventative, Lichtenwalner said, is hygiene and washing your hands after coming in contact with any farm animal or what comes out of that animal in the form of raw manure, compost or fertilizer.
People who work with cattle or other livestock infected with Crypto should be extra vigilant when cleaning and disinfecting areas used by those animals and handlers should always clean anything that has come into contact with those animals including boots, gloves and coveralls.
Ultimately, parasites don’t have to make that jump from livestock to human, as long as farmers and anyone who spends time around farm animals practices due diligence, Lichtenwalner said.
“Check and clear your animals for worms before bringing them home and keep up with a worming program,” she said. “And always, always wash your hands after working with them or working in the garden.”