Global Warming Lengthens Summer and Pest Season

PetMD Editorial
Updated: May 31, 2011
Published: May 21, 2009
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The good news: the Antarctic may not be melting as quickly as some environmental scientists originally feared. The bad news: the earth's warming trend means longer seasons of warm weather for many continents, and thus longer pest seasons.

Many parasites multiply most during warm weather seasons, so we depend on the colder seasons to provide some relief from the parasites and pests that proliferate during these warm weather months. Opportunistic pests such as mosquitoes, fleas, ticks, and internal parasites will become more concerning as we find ourselves dealing with them for longer periods of the year, and the products we use to combat them will become increasingly ineffective as the pests gradually evolve to resist the chemicals. Stronger, hardier fleas; bot flies that lay eggs for most of the year; more roundworms in the yard. Not a pretty thought.

Unfortunately, it looks like we are going to have to get used to it. In the last century, the surface temperature has increased by more than a full degree. This may not sound like much, but it has an enormous impact on seasonal variances. And the global temperature is expected to increase even more over this century. Longer pest seasons will be a way of life, whether we like it or not. This is already evident in areas that have been affected by climate change with longer warm months, and warmer cold months, where the populations of both fleas and ticks has increased incrementally. Obviously, we need to plan for other resources to avoid total body infestations, or to avoid life threatening infections from the more noxious pests that cannot be seen as easily, such as round worms -- which can infect the intestines and eyes in both pets and people -- and the Heterobilharzia americanum and Leptospira spirochete parasites, which are acquired in aquatic environments. Heterobilharzia americanum is typically associated with summertime recreation. That is, dogs, and people, catch this parasite while swimming, playing in wet areas, and playing in dirt that is infected with the parasite. Dogs can also catch it if they have been boarded in a kennel for any amount of time, or if they spend any time out doors where infected animals have been.

And then there are the flies, mosquitoes, ticks, and fleas, to name just a few of the pests that plaque us in the warm weather months. Mosquitoes can transmit the heartworm to your pet, ticks can transmit Lyme disease, and fleas can transmit the tapeworm. And speaking of things that plague, fleas are also thought to be one of the major transmitters of the plague, which is transmissible from animal to animal and from animal to human.

Veterinarians are acquainted with the issues that are looming as a result of global warming and its effect on pest populations. Dr. Patty Khuly is a practicing veterinarian in Miami, Florida, where pet owners and veterinarians are all too familiar with the longer pest seasons. Pet owners in South Florida are accustomed to fighting pests all year long, Dr. Khuly explained, but veterinarians and pet owners up north are afraid of what may happen if the warming trend continues. Longer seasons up north are changing the way diseases are treated, she said.

"Tick diseases are seasonal up north," Dr. Khuly said. "Once we start seeing longer tick seasons, we will see more of the diseases associated with them."

These tick borne diseases can include Lyme disease, Rocky Mountain spotted fever, and Ehrlichiosis, to name a few. More fleas can mean more tapeworm infections, increased incidences of anemia, and dermatitis. Eventually, there may be little that can be done to prevent these issues.

"Much of what is in our current arsenal for treating fleas and ticks might be insufficient, because our products are not geared toward large scale infestations that will occur due to the longer seasons," said Dr. Khuly.

Dr. Khuly explained this is one of the challenges to combating pests in the subtropical climate of South Florida, where flea and tick products are never 100 percent effective, making it difficult to treat these pernicious parasites over the long term.

Even indoor pets are at increased risk. Cats tend to lay against window screens, where they can be bitten by mosquitoes -- which transmits the heartworm parasite. "The prevalence of heartworm would rise dramatically in the event that global warming were to become a sustained reality," Dr. Khuly said.

Image: Jan-Erik Finnberg / via Flickr