Pathogenesis of filarial hydrocele: risk associated with intrascrotal nodules caused by death of adult Wuchereria bancrofti.

Although testicular hydrocele is the most common clinical manifestation of bancroftian filariasis, its pathogenesis is poorly understood, as is its relationship to inflammatory scrotal nodules following death of adult Wuchereria bancrofti. Between 1994 and 1998, we prospectively determined the incidence and clinical evolution of nodule-associated acute hydrocele in men attending 2 outpatient clinics in Recife, Brazil who were infected with W. bancrofti, had living adult worms detectable by ultrasound in the intrascrotal lymphatic vessels, and were scheduled for treatment with 6 mg/kg diethylcarbamazine (DEC). A total of 132 men developed 173 scrotal nodules 1-7 (mean 4.2) d after DEC treatment and another 47 developed 58 spontaneous nodules before they received DEC treatment. These 179 men with a single 'nodule event' (simultaneous development of > or =1 scrotal nodules) were followed-up by serial physical and ultrasound examinations for 18 months. Overall, 40 (22.3%) men developed acute hydrocele, 3 of whom underwent biopsy and hydrocele repair. Of the remaining 37 men, 9 (24.3%) developed chronic hydrocele and 28 had acute hydrocele resolution within 14-210 (mean 60.9) d. Rate of chronic hydrocele was similar for men who received DEC and those with spontaneous nodules. Seventeen (42.5%) men with hydrocele had multiple scrotal nodules, compared with 28 (20.1%) men who did not develop hydrocele (P= 0.007). Of 134 men with single nodules, superior paratesticular nodules were found in 56.5% and 29.7% of those with and without hydrocele, respectively (P = 0.02). Acute hydrocele occurs frequently following death of adult W. bancrofti and single episodes of scrotal nodule formation. Chronic hydrocele may develop following 5.1% of these episodes.