Students in the SDSU course that I teach, Animal Diseases and Their Control, were recently asked to think critically about an uncommon but potentially serious public health problem: the movement of germs from animals to people at petting zoos and fairs. Each year, illnesses such as E. coli O157:H7 and cryptosporidiosis are associated with contact between people (often children) and animals on exhibit.
The students were put in the position of a manager at a hypothetical fair with a petting zoo exhibit. They were asked to come up with ideas that would help prevent human contact with germs from animals sufficient to make them sick. Their ideas had to fit into each of the three main categories of “preventing an effective contact” between animals (or their environments) and people:
- Physical separation – How can people and disease-causing germs exist – and stay – in two completely different places?
- Decreasing dose-load – Not every contact with potentially dangerous germs makes people sick. A large enough number (“dose”) of germs is needed to cause illness. If germ contact occurs, how can their numbers be minimized?
- Minimizing contact time – More time spent around germs means a greater chance of illness. How can the length of time a person is exposed to potentially harmful germs be minimized?
The students’ ideas were based on the fact that the design and staffing of animal exhibits can significantly reduce the chance of a visitor becoming ill from contact with germs that can be found normally on animals or in the spaces they inhabit. The ideas are not a comprehensive list of recommendations. Complete guidelines for preventing human disease in animal settings can be found on the NASPHV website.
Some of the students’ suggestions:
Physical separation. Providing barriers between visitors and animals was a common theme: some ideas went as far as to limit visitors to viewing animals only through a window or video feed! While effective, those ideas run counter to the educational goals of many of these exhibits.
- Set up a double layer of fencing or panels – providing more separation between animals and people, but making it harder to pet the animals.
- Don’t allow visitors to enter the pens with the animals. This provides separation between people and animal manure – the source of most zoonotic illnesses in animal contact situations.
- Make sure pens are regularly cleaned, to separate visitors from manure and soiled bedding.
- Recognize that some animals (young calves, goats) are more common sources of E.coli O157:H7 and other illnesses than others. Consider restricting contact with those animals.
Decreasing dose-load. These ideas were mostly centered around cleaning and disinfection – on both the animal side and the people side.
- Have a regular schedule for volunteers or staff to remove manure from animal pens.
- Regularly clean and disinfect fence and corral panels that both visitors and animals can touch.
- Make sure any animal that is sick or has diarrhea is promptly removed from the exhibit.
- Design the facility so people have to pass by sinks or sanitizing stations as they leave.
- Designate volunteers to keep sinks stocked with soap and towels and encourage all visitors to wash their hands.
- Make the hand-washing experience accessible and fun for kids, meaning sinks that are reachable by small children and that are colorful and inviting. Reward kids with a sticker for washing their hands.
- If strollers are allowed, decrease the number of germs that people might take home by having a “stroller wheel wash” station. Volunteers could clean and disinfect stroller wheels before leaving the exhibit. A disinfectant mat at the exit could help reduce the number of germs carried home.
Minimizing contact time. These ideas reflected the fact that the more time spent with germs –whether from the animals or a contaminated environment, the greater the chance of illness.
- Design the exhibit with a set, one-way traffic flow.
- Use volunteers to keep visitor traffic moving through the exhibit, discouraging excessive time spent with any one animal.
- Limit the number of hours or even days the exhibit is open.
- Put animals that are more common sources of germs (e.g., young calves or goats) towards the end of the exhibit, closer to the hand washing stations. Or even have a hand sanitizer or sink right next to those animals.
Anyone assisting with animal exhibits can use the three principles of “preventing effective contacts” to come up with ideas of their own to keep visitors safe when visiting the animals. A complete reference, with background and prevention strategies is the Compendium of Measures to Prevent Disease Associated with Animals in Public Settings website.