Giardia in dog parks
There is a recent paper in Preventive Veterinary Medicine about a study of Giardia in canine stool samples collected from urban green areas around Pisa, Italy (Papini et al). The authors went to parks and similar areas and collected stool samples off the ground. They then tested the samples for the presence of Giardia and (very importantly) tested the Giardia to determine whether they were types that typically only infect dogs or whether they were types also found in people.
They found that 31% of stool samples contained Giardia. That's higher than in some recent North American reports. The number of Giardia cysts ranged from 2 to 1428 per gram of feces. Less than 1% of the Giardia were types that are of concern for transmission to people. Therefore, they concluded that parks pose a risk to dogs, since there is a good likelihood that dogs could be exposed to Giardia. However, the risk to people from Giardia found in these parks is minimal given the types that were found.
The risks to dogs and people can be decreased by the simple act of picking up poop.
More information about Giardia can be found on the Worms & Germs Resources page, and in our archives.
Watch your step in Dutch parks
I recently wrote about a Dutch study of zoonotic parasites in pet feces and pets' haircoats. As part of that study, they asked pet owners about certain behaviours in their pets, and got some interesting answers.
60% of pets visit the bedroom (I'm surprised that's not higher), with 45% of dogs and 62% of cats allowed on the bed, and 18% of dogs and 30% of cats allowed to sleep in the bed with the owner. While the UK's Chief Vet has warned against allowing pets into bedrooms and allowing them to sleep in people's beds, I don't have the same concerns - as long as common sense prevails.
45% of cats are "allowed" to jump on the kitchen sink. I don't know if they truly mean allowed, or whether the cats simply do this. I certainly don't "allow" my cat to be on the kitchen counter, but it's certain possible he is when I'm not looking. There are some potential concerns about pets hanging around food handling areas, so it's best to actively discourage this behaviour.
55% of owners clean their litterbox more often than twice a week. While daily cleaning is important for high risk people and high risk households, and is ideal for everyone, less frequent cleaning like this is acceptable for most people as long as it's done properly (See our Resources page for details about litterboxes).
15% of dog owners and 8% of cat owners reported always washing their hands after contact with their animals. This is surprisingly high - I wonder if it's really true, or whether some of those do it regularly but not always, or some think they should do it but don't really. Certainly, regular handwashing is important and it's ideal to do it after every animal contact, but that's admittedly hard to do in a household. I try to have good hand hygiene practices but I certainly don't always wash my hands everytime I should. Handwashing after every animal contact is more important for high risk people such as people with weakened immune systems.
39% of dog owners never clean up their dogs' feces. WHAT??!! That's surprisingly high. When you consider how densely populated the Netherlands is, and that there are around 1.8 million dogs in the country, that's a lot of dog poop. That could be one reason why they found that dogs that were allowed off the leash outside were much more likely to have Toxocara eggs on their coat.
Dog park closed because of bleach contamination
A dog park was closed because of an attempt by a dog-owner to disinfect puddles. The woman was seen pouring a gallon of bleach into a mud puddle, sparking an investigation. The site was closed while city staff pumped out puddles. The woman told the person that witnessed and reported the incident that her dog had contracted the intestinal parasite Giardia in the park, and she was trying to sanitize the water. However, authorities believe it may in fact have been a malicious act (i.e. an attempt to poison the dogs using the park).
Firstly, there's no way the woman could know that the park (let alone a specific puddle) was the source of her dog's infection. Giardia can be found in the environment and in the stool of a small percentage of healthy dogs (~7% in many studies).- Secondly, pouring a toxic substance into the puddles in the park is obviously not an appropriate response. Bleach is a good disinfectant when it's used right, but disinfecting outdoor surfaces like this is essentially impossible. Organic debris (e.g. mud) will readily inactivate bleach, but the bleach could still make an animal sick if too much (too high a concentration) is swallowed, because it's very caustic.
- Thirdly, for this woman to take matters into her own hands like this without consulting someone who knows something about infectious diseases, and potentially exposing a lot of animals to high levels of bleach is irresponsible. If there was concern about the park as a source of infection, the appropriate response would have been to talk to city staff.
In reality, the risk to other dogs was probably pretty low. It’s pretty obvious when there's a lot of bleach somewhere (even just based on the smell), and in general dogs would probably be very reluctant to drink bleach-contaminated water.
One officer stated that he suspects the Giardia story was an excuse contrived by the woman when confronted by the passer-by who witnessed the bleaching incident. That’s certainly possible, but I’m surprised someone would come up with a specific excuse like Giardia. If the woman is found, that should be easy to figure out - the diagnosis would have to be in her dog's medical record. Police stated that the woman, if identified by the authorities, could potentially face animal cruelty charges. I think that’s pretty unlikely, considering what usually has to happen for someone to actually be charged and convicted of animal cruelty. I suspect this really was an overzealous response by someone who lacks common sense. There was no comment about whether the woman would be billed for the city staff time required to deal with the clean up - that might be a more effective deterrent to similar incidents in the future!
Parks are inherently a high-risk environment for exposure to infectious diseases. Whenever you mix large numbers of animals, especially in an area where they often pass stool, there is an increased risk of disease transmission. You have to accept that when going to a park. People should also ensure that they never take a sick animal to a park, promptly clean up stool, and may sure that their pet is on an appropriate vaccination and deworming program. Disinfection of a park will never be part of the infection control program.
More information about Giardia can be found on the Worms&Germs Resources page.
Parvo in the park
A park in Orange County, Florida has been closed because a dog with canine parvovirus was found in the park. Canine parvovirus is a potentially serious infection in dogs (mainly puppies) that can cause severe vomiting and diarrhea. In some cases, it can be fatal. Proper vaccination against parvovirus is critical for puppies. In Orange County, they have closed the park because of concerns about parvovirus transmission. The have also apparently "bleached the dog park".
Parvovirus can live for a very long time in the environment, however disinfecting an outdoor environment is not only impractical, it's impossible! We can disinfect clean, smooth surfaces like sealed ceramic floors and smooth countertops, but we can't disinfect outdoor environments with permeable, porous surfaces and abundant organic debris (dirt). Bleach is not active in the presence of organic debris, and porous surfaces allow bacteria and viruses to escape contact with disinfectants. So, while it's good to see that they are concerned about disease transmission, this particular aspect of their control efforts isn't going to be effective.
Parvovirus exposure is an ever-present risk in areas where multiple dogs congregate. The virus can be shed in the stool of even healthy-looking dogs. In this situation (like all others) the emphasis should be on keeping high-risk dogs (e.g. unvaccinated puppies) out of these areas, not closing the park altogether and attempting to disinfect it. Parvovirus vaccination is very effective, and properly vaccinated adult dogs are quite low risk. Prompt removal of stool by dog owners helps reduce the risk further by decreasing the risk of environmental contamination. Therefore, the three most important control measures are:
- Ensure puppies are properly vaccinated.
- Keep puppies out of areas visited by numerous dogs until they have been fully vaccinated.
- Scoop poop.
And since the focus of this site is zoonotic diseases, remember that canine parvovirus is not transmissible to people. Human parvovirus infection (Fifth disease) is caused by a completely different virus.
