AMICROFILARAEMIC CARRIERS OF ADULT WUCHERERIA-BANCROFTI

To determine the extent to which Wuchereria bancrofti infections can b e detected in asymptomatic amicro-filaraemic men in Greater Recife, Br azil, we studied 100 asymptomatic men who were long-term residents (gr eater than or equal to 15 years) of this filariasis-endemic area and w ho were amicrofilaraemic in 60 mu L, of capillary blood collected at n ight. Increasing amounts (1, 5, and 10 mL) of venous blood were collec ted in consecutive weeks, filtered, and examined for microfilariae; 27 men were eventually found to be microfilariaemic and 10 remained amic rofilaraemic but were found to be carriers of living adult W. bancroft i by ultrasound examination of the scrotal area. Thus, 37% of 'amicrof ilaraemic' men (in 60 mu L of blood) were found to be infected by more thorough investigation. Ultrasound is a valuable tool to identify adu lt worm infections in amicrofilaraemic persons, particularly for evalu ation of serological assays and immunological studies in which the dis tinction between 'amicrofilaraemic adult worm carriers' and 'endemic n ormal subjects' is critical.