How is it Diagnosed? Through B. S. Examination for microfilaria. Clinical Manifestations The clinical manifestations of filariasis depend upon the stage in the course of infection in the human host and the worm load (adult). The stages in the course of infection may be described as follows: A. Stage of Invasion The infective larva gains its entry into the human host and starts undergoing further development. Diagnosis at this stage rests on the triad of: Eosinophilia, lymphadenopathy and a positive intradermal test with the supporting evidence of history of residence in an endemic area. B. Asymptomatic or Carrier Stage stage is usually with no clinical manifestation. The microfilaria (mf) carriers are usually detected by night blood examination. C. Stage of Acute Manifestations These comprise filarial fever, lymphangitis, lymphadenitis and lymphoedema of the various parts of the body and epididymo – orchitis in the male. It is mainly because of the infection of the lymphatic vessels (channels) by the adult worm. D. Stage of Chronic Manifestations The clinical manifestations comprise of elephantiasis of genitals, legs or arms, hydrocele, chyluria, etc.