The nigua, the Cuban jigger, is a pest of serious consequence, and the mal de nigua (jigger sickness) sometimes causes the death of lower animals and men.
Of the Sarcopsyllidae the best known species is the "jigger" or "chigoe" (Dermatophilus penetrans), indigenous in tropical South America and introduced into West Africa during the second half of last century.
The impregnated female jigger burrows into the feet of men and dogs, and becomes distended with eggs until its abdomen attains the size and appearance of a small pea.
In later improvements the secondary circuit of this jigger was interrupted by a small condenser, and the terminals of the relay and local cell were connected to the plates of this condenser, whilst the sensitive tube was attached to the outer ends of the secondary circuit.
- A, antenna; P S, jigger or oscillation transformer; C, condenser; 0, Fleming oscillation valve; B, working battery; T, telephone; R, rheostat; E, earth-plate.