Genomics study traces heartworm’s ancient spread across continents

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A new global genomics study is reshaping the history of canine heartworm disease, suggesting Dirofilaria immitis did not spread worldwide only through recent dog movement, but likely traveled with ancient canids and human migration over much longer timescales. The study, published in Communications Biology, analyzed whole-genome sequences from 127 adult heartworms collected in nine countries across four continents. Researchers found strong regional population structure, evidence of Asian-Australian admixture that may be linked to dingo movement, and signs that some heartworm dispersal in Central America may reflect later human-driven dog movement during colonization. Texas A&M, which highlighted the findings in an April 1, 2026 release, said the work offers the first full-genome global comparison of the parasite. (nature.com)

Why it matters: For veterinary professionals, the study is less about rewriting natural history for its own sake and more about building a genomic baseline for today’s clinical and epidemiologic questions. Texas A&M researchers said that understanding how heartworm populations are related could help trace unusual cases, interpret regional emergence, and support future work on suspected macrocyclic lactone resistance. That comes as heartworm remains a significant threat in U.S. practice, with the American Heartworm Society’s latest incidence map showing continued nationwide risk and shifting hotspots based on 2025 testing data. (vetmed.tamu.edu)

What to watch: Expect follow-up work to focus on under-sampled regions, stronger timelines for parasite movement, and whether these genomic patterns can be tied more directly to surveillance and resistance monitoring. (nature.com)