Which parasite is a nematode transmitted by mosquitoes in dogs?

• A. Heartworm
• B. Tapeworm
• C. Coccidia
• D. Flea

Answer: (A)

Heartworm is a nematode transmitted by mosquitoes in dogs. The parasite, Dirofilaria immitis, relies on mosquitoes as vectors: an infected dog has microfilariae in the blood, a mosquito takes up these larvae, they develop inside the mosquito, and are then transmitted to another dog when the mosquito bites. In the new host, the larvae migrate to the heart and pulmonary arteries and mature into adults, causing heart and lung disease that leads to coughing, exercise intolerance, and potentially heart failure if untreated. The other options aren’t nematodes carried by mosquitoes: tapeworms are flatworms transmitted mainly through fleas or intermediate hosts; coccidia are protozoa spread via fecal-oral routes; fleas are ectoparasites, not nematodes.