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Biology - Life Cycle of D. repens

Life Cycle:

Life cycle of D. repens

During a blood meal, an infected mosquito (Aedes, Anopheles, Culex, Mansonia) introduces third-stage filarial larvae of Dirofilaria repens onto the skin of the canine definitive host (but also occasionally humans, especially in Europe), where they penetrate into the bite wound The number 1. In the definitive host, the L3 larvae undergo two more molts into L4 and adults, the latter of which resides in subcutaneous tissues The number 2. Adult females are usually 100-170 mm long by 460-650 µm wide; males are usually 50-70 mm long by 370-450 µm wide. Adults can live for 5 - 10 years. In subcutaneous tissue, the female worms are capable of producing microfilariae over their lifespan. The microfilariae are found in peripheral blood The number 3. A mosquito ingests the microfilariae during a blood meal The number 4. After ingestion, the microfilariae migrate from the mosquito’s midgut through the hemocoel to the Malpighian tubules in the abdomen The number 5. There the microfilariae develop into first-stage larvae The number 6 and subsequently into third-stage infective larvae The number 7. The third-stage infective larvae migrate to the mosquito's proboscis The number 8 and can infect another definitive host when it takes a blood meal The number 1. In humans The number 9, D. repens usually manifests as either a wandering worm in the subcutaneous tissue or a granulomatous nodule, although there are reports of pulmonary dirofilariasis with this species .

Life cycle image and information courtesy of DPDx.

 
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