Rabies in "petting zoo" animals
Rabies in a lamb and cow at a petting zoo (or more accurately, in a communal group of hobby animals) has been reported in Israel. This follows identification of rabies in another lamb from the same group last week. Little is reported about possible sources of infection of these animals, at Kibbutz Neve Eitan, or how widespread human exposure may have been. It's a concern given the serious nature of rabies and the possibility that there was largely uncontrolled contact with the public, which complicates tracing of potential exposures. Given the state of rabies in Israel, the canine rabies variant is most likely the cause.
Presumably, public health and Kibbutz personnel are contacting people in the area to determine who may have had contact with the animals. Casual contact is not a risk for rabies transmission - it is only transmitted through contact of an open wound or mucous membrane (e.g. nose, mouth, eyes) with saliva from an infected animal. The risk of transmission to humans from contact with species like sheep and cattle is pretty low, however the tendency of young animals to suck on things and the fact that people often let them suck on a fingers when playing with them raises the potential for exposure. Anyone identified as having high-risk contact needs post-exposure treatment, consisting of a shot of anti-rabies antibodies and a series of four vaccines over the course of a month (unless they have been previously vaccinated against rabies, in which case they just need two booster shots).
Any animals involved in public displays, petting zoos or other events where there may be contact with the public should be vaccinated against rabies. That's particularly true in areas such as Israel, where rabies is endemic.
Cryptosporidiosis and petting zoos: England and Wales
Petting zoos are very common in the UK (as in many other regions), where approximately 2 million people visit 1000 different petting zoos every year. While the vast majority of petting zoo visits are simply pleasant outings associated with no problems, some people leave with more than just memories... they leave with an infectious disease. A letter in the latest edition of Emerging Infectious Diseases (Gormley et al 2011) describes one of the diseases people can pick up at petting zoos: cryptosporidiosis.
From 1992-2009, 55 outbreaks of intestinal infections associated with petting zoos were reported in England and Wales. (There were presumably many more unidentified cases or even outbreaks.) Of these, 55% were caused by E. coli O157. The second most common cause was Cryptosporidium, a protozoal parasite that is commonly found in feces of calves and lambs, which was responsible for 42% of the outbreaks and affected 1078 people. (Again, this is probably an underestimation of the true numbers because typically there are many undiagnosed or unreported cases of illness for every case that is identified). The number of people involved ranged from 2-541 per outbreak. Twenty-nine people were hospitalized due to the infection.
Factors associated with outbreaks were things that we know are issues with petting zoos:
- Contact with young lambs, calves or kids
- Inadequate hand hygiene facilities
Cryptosporidium outbreaks were also more common in the spring, as opposed to E. coli outbreaks which were more common in the summer. This may be explained by the association of the pathogen with contact with young calves, lambs and kids, since these animals are mainly born in the spring.
Alcohol-based hand sanitizers, while excellent for most bacteria, are ineffective against Cryptosporidium. This can also be a contributing factor to outbreaks of cryptosporidiosis, particularly if hand washing stations are replaced with hand sanitizers. While alcohol-based hand sanitizers are certainly better than nothing, their usefulness is limited when resistant pathogens (such as Cryptosporidium) may be present, and when peoples' hands might be contaminated with large amounts of dirt or other debris (e.g. feces).
Petting zoos can be great events, particularly for kids. However, kids, especially young kids (less than five years of age), are at high risk for certain infectious diseases they may encounter at such venues. While petting zoos seem to be improving and governments are paying more attention to making them safer, visitors need to look out for themselves.
- Make sure a hand hygiene station, preferably a hand washing station, is available. Do this before you touch animals.
- Always wash your hands after leaving the petting zoo, regardless of whether or not you touched an animal (since other surfaces you touched may have been contaminated).
- Do not have contact with young calves, lambs, kids (i.e. baby goats) or poultry.
- Do not have contact with diarrheic animals, or animals that appear to have any other health problems.
- Don't take food, drink or anything that might go into a child's mouth (e.g. baby bottles) into the petting zoo area.
- Closely supervise children.
- If you see a poorly equipped or run event, don't be afraid to contact your local public health office. While most petting zoos seem to be improving, some are still pretty bad and may need to be forced to do things right.
Cryptosporidiosis from wildlife centre lambs
The May 2010 edition of Emerging Infectious Diseases contains a report about an outbreak of cryptosporidiosis in Scotland (McGuigan et al. 2010). Cryptosporidiosis is a common parasitic disease caused by Cryptosporidium, a protozoal parasite. It causes diarrhea, which is usually annoying (to say the least) but self-limiting in healthy people, but the infection is potentially fatal in people with compromised immune systems.
An investigation was launched after a single case of cyrptosporidiosis was diagnosed by a Scottish laboratory. The reason a single infection caused such concern is that it was suspected to have originated from contact with lambs at a wildlife centre, so there was potential for exposure of many people. The concerns were valid, since a total of 128 cases of cryptosporidosis were uncovered during their investigation, and 117 of the people affected had visited the wildlife centre. Another 252 unconfirmed cases were also identified.
The investigation suggested that direct contact with diarrheic lambs was the source of infection. Lambs (and calves) are high risk for shedding Cryptosporidium, even when they're healthy. Diarrhea increase the risk of transmission from these animals even more, because diarrheic animals are more likely to (1) shed the parasite and (2) have fecal staining of their haircoats, which increases the likelihood of fecal contact for every person and animal around them. That's why young ruminants (e.g. lambs, calves) as well as young poultry are considered inappropriate for petting zoos and other similar public animal contact events. This outbreak is yet another example of why these recommendations are in place.
At the wildlife centre in this study, children were apparently encouraged to pick up the lambs, despite visible diarrhea. No handwashing facilities were near the lamb petting area and it took "considerable effort" to find a location to wash your hands anywhere on site. Alcohol hand sanitizers were available, however Cryptosporidium is resistant to alcohol. Handwashing is a critical component of disease prevention, but unfortunately it is very underused. In general, people are becoming much more aware of the need for handwashing, but even so, if handwashing facilities are not conveniently located, people tend not to go to much effort to find them. That leads to increased risk of infections, as was the case here.
Control measures at the wildlife centre implemented after the investigation included removal of the lambs (who should never have been there anyway), disinfection of the premises with bleach (although disinfecting a farm environment is very difficult, and Cryptosporidium is also resistant to bleach), and stopping direct contact between animals and visitors.
As we enter the season when there are more fairs, petting zoos and other animal contact events, facility managers need to pay attention to important factors like:
- Readily available hand hygiene facilities
- Good design to control the types of human-animal contact and to steer people towards hand hygiene stations
- Appropriate animals: no calves, lambs or chicks
- Proper supervision of people and animals
A little common sense goes a long way. The goal is to set up these events so that there is still a beneficial impact of seeing and interacting with animals while reducing (but never eliminating) the risk of disease transmission. A 100% safe petting zoo is not achievable (there's always some risk in life), but some pretty simple measures can greatly reduce the risks while still providing excellent entertainment and educational opportunities.
