Editor's Note: Read the second part of this story, Preventing zoonotic disease on the dairy. Those working in close contact with dairy cattle may be exposed to a variety of microorganisms that can cause disease. Some of these microorganisms can affect both humans and non-human animal species. A disease that can be transmitted between humans and other animal species is called a zoonotic disease or zoonosis.

Zoonotic diseases can be acquired by people directly from animals, from instruments and equipment used on animals or from the environment. Humans can be exposed to zoonotic organisms when bodily fluids from infected animals come in contact with our mucous membranes and non-intact skin. Contaminated bodily fluids can be aerosolized, ingested or injected via needles or other sharp objects.

Although many have grown up around livestock and feel that their immune systems are up to the challenge, it is important to understand that zoonotic diseases have the potential of affecting anyone. While individuals from urban backgrounds may be naïve to zoonotic organisms on the dairy farm and be more susceptible to some diseases, even seasoned employees can contract zoonoses while working with dairy livestock.

Symptoms of zoonotic diseases in humans will vary greatly according to the disease in question, level of exposure, the person’s immune status, stress level and other personal factors. Some zoonotic diseases will cause similar effects in people as in cattle, while others will produce varying degree and severity of disease in different species.

What if a worker is feeling ill? How do I know if it is a zoonotic disease?
Symptoms alone usually will not allow a worker to tell if he or she is experiencing a zoonotic disease or if they were exposed at work. Whenever a worker feels ill, they should visit a health-care provider. It is important that they mention to the health-care provider that they work with dairy livestock.


If, after diagnostic procedures, they are advised that symptoms are possibly due to a zoonotic disease, they should speak with a supervisor and take the necessary precautions to minimize spread to other people and animals.

Keep in mind that people can transmit diseases to other animal species including cattle. The strategies listed above should aid with the prevention of disease transmission from dairy cattle to humans and vice versa. PD

Noa Roman-Muniz, DVM, MS, Colorado State University.

David Douphrate, PhD, MPT, MBA , CPE, University of Texas School of Public Health.