Zoonoses - Animals Can Make You Sick

  • Rosenman, Kenneth

While animals around the farm may appear healthy, they may be carrying a disease that can infect you and family members. These diseases can be transmitted through everyday contact with the animal, or through contact with their carcasses or other by-products. A person can also be infected by just entering a contaminated animal housing facility. Diseases that can be transmitted from animals to humans are referred to as zoonotic diseases or zoonoses.

It is important for farmers to know about zoonotic diseases because the symptoms are frequently similar to other types of illnesses. Symptoms of psittacosis (ornithosis) for example, range from a flu-like illness to acute pneumonia. For proper diagnosis and treatment, your healthcare professional must be also aware of any potential sources of the infection. While there are many zoonotic diseases, this factsheet will address those where there is some potential for infection in Michigan. This is only a partial list of zoonotic diseases in the state.

Some of the more obvious zoonotic diseases can be the result of being scratched or bitten by an animal or from milking. Symptoms of one of the most common zoonotic diseases, Cat-Scratch Fever, can include localized pain, swelling, redness and fever. Another common zoonotic disease is Milkers' Nodules, which frequently results in pustules on the hands and fingers after being infected. Ringworm is a common zoonotic disease that causes pustular nodules with hair loss in exposed areas of the body head or arms.

Zoonotic diseases are caused by bacteria, viruses, chlamydia, fungi and parasites. Animal sources for zoonosis include cattle, sheep, horses, pigs, chickens, turkeys, dogs, cats, rodents and some wild animals. Depending on the disease, all of these animals can be a source of infection (See Table 1).

Steps to minimize the risk of contacting a zoonotic disease include wearing gloves for certain activities, a well-managed vaccination program, and good sanitation and personal hygiene.

Table 1. Animal Diseases that can infect humans
Disease Common Source Clinical Effects Mode of Acquisition Prevention
Bacterial Diseases
Campylobacter Cattle, Sheep Pigs, Dogs Rodents Poultry Acute gastroenteritis nausea headache, diarrhea Direct contact food contaminated with animal feces Avoid contact with infected animals and feces contaminated food
Cat-scratch diseases Cats, Dogs Fomites Fever, primary skin papule, regional lymphadenopathy Direct contact with infected animals Avoidance of animal scratches and puncture wounds
Salmoneliosis Cattle, Cats Dogs, Horses Poultry, Turtles Chills, fever, headache, diarrhea, vomiting Direct contact with animal or its feces, food contamination from infected animals Improved food processing and preparation
Viral Diseases
Encephalitis Horses Rodents Lethargy, fever headache, disorientation Mosquito or tick bite Protective clothing, insect repellents
Rabies Cats, Dogs Raccoons Skunks, Bats Foxes Fever, headache, agitation, confusion, seizures, excessive salivation, death Animal bite, contact with infected tissue, body fluids or feces Avoid contact with suspected animals, local wound care, pre- and post- exposure immunization/ vaccination
Chlamydial Diseases
Psittacosis (Ornithosis) Pigeons Turkeys Parakeets Parrots Fever, headache, pneumonia Inhaled from infected birds, carcasses, secretions and contaminated facilities Avoid contact with infected birds, control of disease with antibiotics
Fungal Diseases
Ringworm Cats, Cattle Skin lesions Direct contact Avoid close contact with infected animals, Children and individuals with immune suppressed system are more susceptible
Parasitic Diseases
Tosocariasis (Visceral larval migrans) Dogs Raccoons Cats Eye disease, brain disease Ingestion and contact with infected ovum of parasites Treat pets, avoid fecal contaminated soil and sandboxes
Toxoplasmosis Cats, Sheep Undercooked meat Fever, lymph- adenopathy, abortion, still- birth, mental retardation Ingestion of infected meats, oocysts in fecal contaminated soil Proper disposal of cat feces, cook meat well, avoid contaminated soil (especially pregnant women and immune compromised individuals)
Scabies Dogs Raccoons Itching skin Lesions Direct contact with infected animals Treat pets, avoid contact with infected animals

Michigan State University.

Kenneth D. Rosenman, M.D., Occupational Medicine, Michigan State University, 5/92. Funded by the National Institute of Occupational Safety and Health - #UO5/CC-4506052-01.

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