Monday, 27 June 2011

Maps of Dog and Cat Parasites in the US

The Companion Animal Parasite Council (CAPC) website,, has posted maps of the United States showing the prevalence of dog and cat parasites based on lab results at two commercial laboratories. If you’ve ever wondered how common the common dog and cat parasites actually are, and you live in the US, these maps are enlightening. There are maps for tick borne diseases, hookworm, whipworm, Toxocara (roundworm), and heartworm.

One should take care drawing conclusions from the results. This data is not based on a survey of all dogs and cats, or even a survey of a representative sample of all dogs and cats. It is data based on lab results of dogs and cats (presumably dogs and cats with owners and homes) whose samples were submitted to two specific commercial laboratories. We can assume that submission of these samples was done for a reason, even if it was just a routine health check; we don’t know whether parasites were suspected in some or most of these animals, or what the average age of the animal was.

You can look at two presentations of the data: traditional and three-dimensional. The traditional is best if you are only interested in looking at data from one state. If you want to compare, however, I’d suggest the three-dimensional. It gives you an immediate visual comparison between neighbouring states and various regions based on percentage positive. The map for Lyme disease clearly – and unsurprisingly – shows a concentration in the northeast, while hookworm's stronghold in the southeast is equally obvious.

I wish this data included Canada, although I understand why it doesn’t. Looking at the results for the northern states may provide clues to prevalence in southern Canada (and what the heck is going on with Toxocara in North and South Dakota?), but there may be differences in veterinary care and other variables that can’t be taken into account.  I still think these maps are very interesting, even with all the unanswered questions.

Wednesday, 22 June 2011

Do Bedbugs Spread Diseases?

Bedbugs are in the news a lot these days. Bedbugs are on the rise; there’s an epidemic. Bedbugs have become resistant to the chemicals we’ve been using for years to kill them. The bugs are in used furniture, on airplanes, and they’re adept at spreading from one apartment to another by traveling along plumbing pipes. Some envision a world where we lose control altogether and everyone has bedbugs, like we all have the occasional spider now.

There’s a difference of course. Bedbugs don’t just live in our houses and they can’t be swept away. They live in our beds. They feed on our blood. The one saving grace has always been that they don’t transmit disease. They ingest blood pathogens when they feed, but no one has ever been able to demonstrate that they are capable of passing any of them on. Until now.

Apparently researchers in Vancouver investigated whether bedbugs could be responsible for the spread of antibiotic resistant bacteria, and found evidence that they could. They found bedbugs carrying antibiotic resistant bacteria, and suggested that because bedbug bites cause a break in the skin, not to mention subsequent scratching, they might provide an opportunity for these bacteria to colonize and cause infections.

As far as I can tell, it’s not proven yet, but the possibility that bedbugs might be spreading these agents looks stronger than ever before.

Lowe, Christopher F., and Marc G. Romney. "Bedbugs as Vectors for Drug Resistant Bacteria." Letter. Emerging Infectious Diseases, 2011 17:6.