Is the causal agent of dog heartworm a virus, similar to St. Louis encephalitis?

The correct answer is that the causal agent of dog heartworm is not a virus, making the statement false. Dog heartworm, scientifically known as Dirofilaria immitis, is actually caused by a parasitic worm, specifically a type of nematode. This parasite is transmitted to dogs through mosquito bites, where the infective larvae enter the host and mature into adult worms that can live in the heart and major blood vessels.

In contrast, St. Louis encephalitis is caused by a viral infection, specifically the St. Louis encephalitis virus, which is transmitted by mosquitoes and affects the central nervous system. Though both conditions are mosquito-borne, the agents involved—one being a parasitic worm and the other a virus—highlight their distinct biological classifications and disease mechanisms. Understanding this distinction emphasizes the variety of pathogens transmitted by mosquitoes and the importance of targeted vector control measures.