Quidel Corporation is engaged in the development, manufacturing and marketing of diagnostic testing solutions. The Company's diagnostic testing solutions primarily include applications in infectious diseases, women's health and gastrointestinal diseases. It sells its products directly to end users and distributors, in each case, for professional use in physician offices, hospitals, clinical laboratories, reference laboratories, universities, retail clinics and wellness screening centers. It markets its products in the United States through a network of national and regional distributors and a direct sales force. Internationally, it sells and markets primarily through distributor arrangements. Its diagnostic solutions are used in the detection and diagnosis of many critical diseases and other medical conditions, including autoimmune diseases, bone health and thyroid diseases. It provides diagnostic testing solutions under various brand names, including Quidel, QuickVue+ and Thyretain.