Sheathed microfilaria with daytime periodicity is:
|A||W bancrofti B.|
a. Microfilaria of Loa Loa shows daytime periodicity.
b. The vector for Loa loa filariasis are flies of the genus Chrysops. During a blood meal, an infected mango fly introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the bite wound.
c. The larvae develop into adults that commonly reside in subcutaneous tissue. Adults produce microfilariae measuring 250 to 300 μm by 6 to 8 μm, which are sheathed and have diurnal periodicity. Microfilariae during the day are found in peripheral blood, but during the noncirculation phase, they are found in the lungs.
d. The fly ingests microfilariae during a blood meal. After ingestion, the microfilariae lose their sheaths and migrate from the fly's midgut through the hemocoel to the thoracic muscles of the arthropod.
e. There the microfilariae develop into first-stage larvae and subsequently into third-stage infective larvae.
f. The third-stage infective larvae migrate to the fly's proboscis and can infect another human when the fly takes a blood meal.