Open sewers and flowing sewage are common sights in the suburbs of Harare, posing significant health risks. In addition to contaminating nearby water sources, such as wells, the concentration of human waste attracts flies and other disease vectors. Flies flourish in areas with poor sanitation, contributing to the spread of a number of diseases, including cholera and typhoid, but also trachoma, a disease of the eye that causes permanent blindness and affects 40 million people worldwide, including in Zimbabwe.