WHO estimates almost half of 46 million blood donations in low-income countries are inadequately tested; in Africa up to 10% of new HIV infections are caused by transfusions. A University of Toronto-developed yeast-based blood screening tool will detect combinations of diseases. Like baking yeast, it can be stored dry, and can be grown locally with minimal equipment and training, improving accessibility in rural areas. We will create a ready-to-use, yeast-based blood screening tool, for simultaneously detecting combinations of diseases.