Which statement about dog heartworm transmission is correct?

Which statement about dog heartworm transmission is correct?

• A. It is transmitted by fleas from an infected dog.
• B. It is transmitted by mosquitoes from an infected dog.
• C. It is transmitted by direct dog-to-dog contact.
• D. It is caused by a bacterium.

Answer: (B)

Heartworm disease relies on a mosquito to transmit a parasite. When a mosquito bites an infected dog, it inhales microfilariae, which develop into infective larvae inside the mosquito. The next time that mosquito bites another dog, those larvae are deposited and migrate to the heart and pulmonary arteries to mature into adult worms. Because of this mosquito-borne lifecycle, fleas do not spread heartworms, direct dog-to-dog contact cannot transfer the infection, and the disease is caused by a parasitic worm, not a bacterium. So the statement that heartworms are transmitted by mosquitoes from an infected dog is the correct one.

Heartworm disease relies on a mosquito to transmit a parasite. When a mosquito bites an infected dog, it inhales microfilariae, which develop into infective larvae inside the mosquito. The next time that mosquito bites another dog, those larvae are deposited and migrate to the heart and pulmonary arteries to mature into adult worms. Because of this mosquito-borne lifecycle, fleas do not spread heartworms, direct dog-to-dog contact cannot transfer the infection, and the disease is caused by a parasitic worm, not a bacterium. So the statement that heartworms are transmitted by mosquitoes from an infected dog is the correct one.