One concern with uncommon pets is our relatively poor understanding of the infectious agents they may carry. For our "established" pet species, we have a reasonable understanding of what bugs tend to be present and which animals may be at higher risk. The less common the pet, the less research tends to be available, making it harder to assess risks and determine what types of prevention programs need to be in place.
A recent study published in Veterinary Parasitology (Levecke et al. 2010) provides information about chinchillas and the parasite Giardia. This Belgian study involved collection of stool samples from 80 healthy pet chinchillas from 4 households and 4 breeders. They identified Giardia in a rather astounding 66% of samples. Young animals were more likely to be infected, as were animals that participated in shows (I didn't realize there were chinchilla shows).
A subset of samples were typed using molecular techniques to determine the Assemblage (strain/type) of the Giardia. This is very important from a human health standpoint, because some types of Giardia can infect both animals and humans, while others are more host-specific. Most samples (86%) contained Assemblage B. However, a combination of different Assemblages was common, and Assemblages C (71%), A (52%) and E (9.5%) were also found. Importantly, all positive samples contained at least one of Assemblages A or B, which are types that can cause disease in people. Assemblage C is typically associated with dogs and Assemblage E with livestock, so those results were a little surprising.
What does this tell us? It tells us that a large percentage of healthy chinchillas may be shedding Giardia in their stool, and that they typically shed types that can cause disease in people.
Does this mean people are getting sick from pet chinchillas? Not necessarily, but it indicates there is a risk.
What can chinchilla owners do? It's pretty straightforward. Giardia has to go from the animal's stool to a person's mouth to cause infection. The use of good general management and hygiene practices (especially handwashing) should greatly reduce the risks. As the folks at Barfblog say, "don't eat poop."
Should chinchillas be tested for Giardia? Probably not. A single negative result does not necessarily mean Giardia isn't there or that it never will be. Given the numbers reported here, it's best to go on the assumption that every chinchilla is (or could be) positive, and take appropriate precautions.