Dog heartworms rarely infect humans

While heartworm disease, caused by parasitic worms transmitted by mosquitoes, severely affects dogs, human infections are incredibly rare. These worms, which can grow up to a foot long in canine hearts, cannot fully mature or reproduce in people. Instead, humans typically develop a small, harmless lung nodule, often mistaken for cancer on X-rays, leading to unnecessary biopsies. Fewer than 100 human cases have been documented in the U.S. since the 1960s, highlighting the effectiveness of pet prevention. This low incidence underscores the vital role of veterinary care in breaking transmission cycles and protecting both animal and human health.