A 20-year-old male presented with high-grade fever, groin pain and a swollen scrotum for 1 week and are worsening progressively. On examination, Tender inguinal lymphadenopathy Scrotal swelling with hydrocoele Lymphatic streaking Blood samples are taken and a parasite infection is suspected. Which of the following is the most likely organism: -

This is a case of filariasis (acute lymphadenitis) due to Wuchereria bancrofti. Microfilariae are found in blood, hydrocoele and other body fluids. 1 Wuchereria bancrofti Sheath, no nuclei in the tip of the tail 2 Brugia malayi Sheath, 2 distinct nuclei in the tip of the tail 3 Loa loa Sheath, nuclei extending to the tip of the tail 4 Onchocerca volvulus (skin) No sheath, no nuclei in the tip of the tail 5 Mansonella perstans No sheath, nuclei extending to the tip of the tail 6 Mansonella ozzardi No sheath, no nuclei in the tip of the tail 7 Mansonella streptocerca (skin) No sheath, nuclei extending to the tip of the hooked tail