Since it seems like everyone wants to talk about heartworms in an effort to sell you something, but is rare to hear anything new, it was really refreshing to really be scared by some of the statistics and language being used by the experts.

I was recently the guest of Novartis, the makers of Interceptor Heartworm prevention, at a small two day meeting in Tucson, on parasite control. Speaking were Dr. Noble Jackson from the University of Arizona (U of A) and Dr. Bowman of the Companion Animal Parasite Council (CAP-C).

Dr. Jackson has been looking at heartworm levels in the Coyote population in Arizona and the data is quite startling for those who believe that heartworm does not exist in Arizona. In Pinal County, which Includes Casa Grande where I live, the infection rate Dr. Jackson has seen is 34%. In Cochise county, that includes Sierra Vista where I used to live, the infection rate is 11%.

Now Dr. Jackson’s work is not finished or published yet, and the sample sizes are relatively small – 160 Coyotes for the whole state. But even allowing for statistical anomalies these results make you sit up and take notice.

Dr. Bowman, however, had the most disturbing news to my ears, in that there have been two confirmed cases of heartworms in humans. Heartworm infection in humans is extremely difficult to detect, since it looks a lot like lung cancer (infection shows up as coin sized lesions in the lungs that can only be definitively diagnosed by thoracotamy) and so the actual rate of infection is sure to be significantly higher.

There is currently mandatory reporting of heartworm positive cases in three states, and significant restrictions on exporting positive dogs.

Heartworms are not that scary for dogs, cat or humans compared to a lot of other parasites, the issue is that prevention is so easy and so successful that makes the current epidemic so sad.