(Bancroftian, Malayan, and Timorian)

Most filarial infections are asymptomatic. Even in asymptomatic people, adult filarial worms commonly cause subclinical lymphatic dilatation and dysfunction. Lymphadenopathy is the most common clinical sign of lymphatic filariasis in children, most frequently of the inguinal, crural, and axillary lymph nodes, in association with living adult worms. Death of the adult worm triggers an acute inflammatory response, which progresses distally (retrograde) along the affected lymphatic vessel, usually in the limbs. If present, systemic symptoms, such as headache or fever, generally are mild. In postpubertal males, adult Wuchereria bancrofti organisms are found most commonly in the intrascrotal lymphatic vessels; thus, inflammation resulting from adult worm death may present as funiculitis, epididymitis, or orchitis. A tender granulomatous nodule may be palpable at the site of the dead adult worms. The chronic manifestations of lymphedema and hydrocele rarely occur in children. Recurrent secondary bacterial infections hasten the progression of lymphedema to its advanced stage, known as elephantiasis. Chyluria can occur as a manifestation of bancroftian filariasis. Cough, fever, marked eosinophilia, and high serum immunoglobulin E concentrations are manifestations of the tropical pulmonary eosinophilia (TPE) syndrome.