Heartworm disease, a potentially fatal parasitic infection in dogs, has a far older and more complex history than previously understood. New research published in Communications Biology suggests the parasite Dirofilaria immitis co-evolved with canids—including wolves and dingoes—over millennia, well before significant human influence.
The Spaghetti-Like Parasite: A Deadly Threat
Heartworm disease is transmitted to dogs through mosquitoes. The worms themselves can grow up to 11.8 inches long and reside in the heart and lungs, often described by veterinarians as resembling strands of spaghetti. Untreated infections can be fatal.
Reconstructing Parasite History Through Genetics
An international team analyzed over 100 heartworm genomes collected from dogs and wild canids globally. Whole-genome sequencing revealed distinct regional populations shaped by ancient canine movements during ice ages. This challenges the long-held assumption that heartworm spread primarily through modern human activity.
Australia’s Ancient Connection
Genetic signatures in Australian heartworms hint at a possible link to parasites found in Asia. The research suggests heartworm may have arrived in Australia with the first dingoes, which migrated from Asia thousands of years ago. While not definitive, this points to an ancient connection predating European colonization.
“For decades, we assumed heartworms were spread mainly through recent human activity. What we’re seeing instead is evidence of deep co-evolution between heartworms and their canine hosts, even before humans were part of the picture.” —Dr. Rosemonde Power, University of Stockholm paleogeneticist
Why This Matters: Drug Resistance and Future Research
Understanding the parasite’s evolution isn’t just academic; it has real-world implications. Like with antibiotics, heartworm is developing resistance to common treatments. Knowing the parasite’s origins and genetic diversity can help scientists develop more effective prevention and treatment strategies. Further research, particularly in underrepresented regions, could unravel the mystery of heartworm’s earliest origins.
Ultimately, the study demonstrates that heartworm evolution is more intricate than a simple story of parasites hitchhiking with modern dogs. Local history matters when addressing this ancient disease.
