Lymphatic filariasis may be diagnosed via microscopic detection of microfilaria on blood smears obtained at night In addition, adult worms or microfilaria may be detected with skin biopsy, and ultrasonography can sometimes be used to detect adult worms Nocturnal microfilaria of W bancrofti and B malayi may be provoked to enter the bloodstream during the day with a one-time dose of diethylcarbamazine citrate (DEC) Blood examination should be performed 30 to 60 minutes after administration of DEC PCR and immunologic testing are also available The drug of choice for lymphatic filariasis is DEC (2 mg/kg/dose three times daily after food for 12 days; there is no maximum adult dose) Ivermectin (150 μg/kg; there is no maximum adult dose) is effective against the microfilaria of W bancrofti but has no effect on the adult worm Consequently, combination therapy with DEC-ivermectin or ivermectin-albendazole is needed for suppression of microfilaremia TPE is treated with DEC for 12 to 21 days DEC is no longer commercially available in the United States but can be obtained through the CDC (404-718-4745) Paradoxical worsening, including encephalopathy, can occur during treatment, especially in patients with high organism burdens Standard precautions exist for isolation of patients with lymphatic filariasis There is no human-to-human transmission of microfilaria and adult worms with the exception of transfusion with infected blood Onchocerciasis (river blindness) is caused by Onchocerca volvulus and transmitted by Simulium blackflies Approximately 18 million people worldwide are infected, over 500,000 have severe visual disability Clinical manifestations may be dermatologic or ocular Skin manifestations present as a pruritic rash with multiple papules that may resolve spontaneously or continue to spread Painless, firm, mobile granulomas may develop in subcutaneous tissue, but rarely cause morbidity Ocular lesions involve both the anterior and posterior segments Anterior segment lesions result from an acute inflammatory reaction around microfilariae and are reversible with therapy Posterior segment lesions involve the optic nerve and chorioretinitis and may result in blindness Diagnosis can be made clinically Laboratory confirmation may be sought via PCR or microscopic examination of skin snips for microfilariae The diagnosis is primarily clinical, as microfilariae may not be present in patients with lymphedema Treatment is with ivermectin in a single dose of 150 μg/kg (there is no maximum adult dose) DEC can cause adverse ophthalmic reactions and is contraindicated in onchocerciasis Standard precautions should be used SEXUALLY TRANSMITTED INFECTIONS