Mississippi leads nation in deadly heartworm infections Justin Glowacki, Sami Jordan and Nischit Sharma • August 18, 2025 “We diagnose about 1 in every 8 dogs with heartworm disease,” said Tamara Huff, shelter director of Hub City Humane Society. “Heartworms are transmitted by mosquitoes … it just takes one bite from one mosquito for your pet’s life to change.”