Zoonotic Diseases Commonly Found In Calves

By Marianne Buza 

When visiting a dairy farm, always observe the calves first because they are the most vulnerable to any disease. If a visitor handles older cows first, they risk bringing pathogens from the older cows to the calves. Calves can be friendly, licking clothes, sucking on fingers, and wanting to play. Despite how fun calves can be, they can also be carriers of zoonotic diseases. A zoonotic disease is a pathogen that can be spread from an animal to a human such as fungi, bacteria, parasites, prions, or viruses. An example would be the bubonic plague, also known as Black Death, that was carried by fleas and transmitted to humans. Calves can have a wide range of pathogens that humans can contract.

One fungus commonly found in calves is Trichophyton verrucosum, more commonly referred to as ringworm. In cattle, this fungus causes a dry, hairless patch and is commonly found on the skin on or around the head. In humans, it will commonly cause itching, reddish skin, and hairlessness. This fungus is transferred from cattle to humans by direct contact with the dry patches on the calf or objects that have been in contact with the skin lesions on cattle. This fungus is relatively harmless to animals but can leave scarring. A doctor should be consulted if a person believes they may have ringworm. Ringworm can also be spread to pets and other animals.

A zoonotic bacterium that is found in calves and even more commonly in adult cattle is Leptospira spp. Leptospirosis causes slow weight gain, low body conditions score, miscarriage, fever, and diarrhea in cattle. In humans it causes flu-like symptoms and can lead to liver and kidney failure. There are vaccines available for cattle for this pathogen. This bacterium is transferred from animal to human through a wound or through mucus membranes, such as eyes, nose, and the mouth, or coming into contact with contaminated water, or aborted fetuses as a result of Leptospirosis, or contaminated body fluids such as urine. This bacterium can also be spread to pets and other animals.

Listeria monocytogenes is another bacterium that is zoonotic. Clinical signs in cattle are depression, head pressing, circling, facial paralysis, fever, miscarriage, and mastitis. In humans, it causes generalized neurological signs and fever. This pathogen is transmitted via contaminated milk, meat, and feces. Listeria can be found in raw, unpasteurized milk and is one of the reasons that milk is now pasteurized. Vaccines are available for cattle for this pathogen. Listeria can spread to pets and other animals.

There are several pathogens commonly found in calves that cause gastrointestinal infections of both humans and cattle. Commonly seen as sources of gastrointestinal infections are the bacterium Salmonella spp., Escherichia coli., Campylobacter jejuni., and Campylobacter coli are commonly seen bacterium sources of gastrointestinal infections., Cryptosporidium parvum, which is a protozoan parasite, is also a common pathogen found in gastrointestinal infections. All these pathogens are spread through manure. Cattle can be asymptomatic and still spread these pathogens. Most calves are carriers of these pathogens, especially if those calves were in contact with other calves or cows. Calves purchased from stock yards are very likely to be carrying these pathogens. These pathogens cause diarrhea in calves. In humans they cause diarrhea, nausea, vomiting and abdominal pain. These types of gastrointestinal infections can be dangerous for humans and calves because they lead to dehydration and more serious issues.

Michigan State University Extension recommends that when purchasing calves, to look for signs of disease. Skin tenting can be used to check for signs of dehydration. Check the rear and flanks of a calf for signs of recent diarrhea. Look at the nose for signs of discharge. Also look to see if calves are active and has a good body condition score.

To prevent these pathogens from causing illness in calves or other animals, a veterinarian should be consulted. A veterinarian can recommend vaccine protocols for individual farms. It is always best to purchase animals that come with health records to know what previous vaccines have been administered along with having received adequate newborn care.

To reduce the risk of contracting a zoonotic disease, always wash your hands after handing animals or any object that has come into contact with them. Consider wearing coveralls or chore specific clothes and shoes to keep pathogens on specific items. After handling these clothes and shoes, wash your hands again, even if you are just putting them in the washing machine. Wearing disposable gloves while encountering body fluids, such as blood and urine, is a strongly recommended protective measure against these pathogens. Do not eat or drink while working around animals to avoid accidental ingestion of pathogens. Always wash your hands first before eating or drinking around animals.