All 50 states have had confirmed cases of heartworm since the disease’s discovery back in 1856. However, since mosquitoes are responsible for transferring the parasite from dog to dog, some areas do pose a higher risk than others.
According to the American Heartworm Society, Mississippi, Louisiana, Arkansas, Texas and Tennessee are the top five worst states when it comes to heartworm diagnosis, in that order. In fact, in a 2016 AHS Incidence Survey, 10 percent of canines in Mississippi tested positive for the parasite. That’s…a lot.
American Veterinarian pointed out that climate change and rising temperatures aren’t helping either, since mosquitoes love humidity, and hot weather decreases the amount of time it takes for heartworms to reach that prime “infectious period.” This means that even those who live outside the high-risk areas aren't totally safe.
Dr. David Dilmore, DVM at Banfield Pet Hospital, adds that while dogs can contract heartworm year-round, the “risk is dramatically elevated in the weeks and months following tropical storms and hurricanes.” This is relevant to dogs across the country, too, not just in areas directly affected by storms. Why? Consider the post-Hurricane Katrina efforts to find foster homes for roughly 250,000 dogs rescued from that storm. Many were sent from Louisiana, a high-risk locale, to states like Wisconsin, a medium-risk locale, and brought the parasite with them.
Remember: All it takes is one infected dog (or coyote) in the neighborhood to create a widespread problem! And since mosquitoes can sneak through screens, indoor-only pets are susceptible, too. Not fun.
The good news is, no matter what state you live in, prevention is possible and effective.