This would include sheep and goat dairy farmers, slaughterhouse operators and veterinarians. In the case of Q-fever from cats it would be anyone who is in the proximity of infected cats when they give birth. Most animals have the potential to carry illnesses that can spread to humans. With respect to Q-fever, the precautions depend on the situation. Once purchased, the animals can be kept in isolation upon arrival to see whether they show signs of any illness that might affect other animals in the herd.
Many people try to keep closed herds with their animals to minimize the entry of diseases.
Though normally people don't use filter masks or gloves when working with animals this can be done if there is any concern over the possibility of transmission of such illnesses. Regular washing of clothes and hands also decreases the risk of disease. Though animals can carry illnesses from one barn to another so can people. Many livestock operations keep their premises closed off to the general public as they don't want to risk having any illnesses brought in on people's boots or clothing. Similarly, many livestock operators will not visit other barns as they don't want to bring anything back to their own barns.