Health education. Health worker giving a lecture about lymphatic filariasis. This disease is caused by parasitic nemotode worms transmitted in larval form by the bite of mosquitoes. The health worker is pointing to a picture of a mosquito. Prevention efforts include avoiding bites and eradicating the mosquitoes. Symptoms of the disease include the swelling of the legs and the scrotum, both shown in pictures on the poster. This condition is rarely fatal, but causes widespread suffering in tropical regions. Treatment involves drug therapy and rigorous hygiene to prevent skin infections. Photographed in Haiti.