Observations on the clinical manifestations and treatment of an experimental infection with Brugia malayi in man.

This paper reports clinical observations made during experimental Brugia malayi infection in man. This was induced by 52 infective larvae-carrying mosquitoes, Anopheles sinensis. A monkey, Maccaca mulatta, was inoculated with infective larvae from the mosquitoes infected with nocturnally periodic type of B. malayi from patients. Six months later, the monkey became a microfilaria carrier. Nine days later, the subject was experimentally bitten by mosquitoes infected from biting the monkey, with an estimated delivery of over 200 infective larvae. Seven days after the infection, general (but fluctuating) pruritus developed, followed by lymphadenitis and swelling of the hand and forearm, with a mild pyrexia for nearly 3 months. The eosinophil counts continuously increased. There were four separate attacks of lymphangitis. On day 142, microfilaraemia was first detected. After two more weeks, the subject was treated with a total dose of 15 g diethylcarbamazine (DEC) over 30 days. During this period, 28 small tender subcutaneous nodules appeared on his arms. After treatment, microfilaraemia gradually disappeared and the swelling of his arms improved. Three months later, the eosinophil count of his blood returned to normal but some temporary and scattered small pruritic erythematous patches still persisted over his left forearm. Lymphangitis has not recurred.