How does LF affect children?
In children, the infection from LF is usually symptomless and not clinically detectable. The damage caused by adult worms in the lymphatic system develops slowly, and it is generally not apparent until children are four or five years of age. However, swollen lymph glands may be observed as early as two years of age. At about seven years, about 30% of infected children will start to show ultrasound-detectable, irregular ballooning of the tiny walled lymphatic ducts and some will have noticeably swollen lymph glands.
Disease progression in girls
By about 13 years, girls may start to show clinically visible signs of infection of the lymph vessels in the leg. Further cumulative damage to the lymphatic drainage system predisposes them to lymphoedema (an abnormal accumulation of lymph fluid in the tissues causing swelling of a limb). This may progress to elephantiasis (painful and disfiguring swelling of the leg, arm, breast or genitals, up to several times their normal size, with thickening of the skin) in adulthood.
Disease progression in boys
By about 11 years, boys may start to show detectable ballooning of the lymphatic vessels in their scrotum. By about 13 years, they may start to develop hydrocele - a fluid-filled, balloon-like enlargement of the sacs around the testes. Scrotal nodules often develop in adulthood and further bacterial infection can lead to massive enlargement of the scrotum and gross deformation of the penis.
Less commonly, boys may also develop lymphoedema and elephantiasis of the extremities, similar to girls. However, the parasites in males seem to prefer the lymphatics of the scrotum over those of the extremities. Thus, genital disease is more common in males, and is the most common of all clinical manifestations of LF.