A patient has blood drawn to test for Chagas’ disease during a health fair in Northridge. Called a “silent killer,” Chagas’ disease affects millions of people worldwide, predominantly in Latin America, and can lead to death from heart failure. The Centers for Disease Control estimates that 300,000 people live with Chagas’ disease in the United States. However, most American physicians rule out Chagas as an exotic problem and don’t think to test for it, depriving thousands of people of diagnosis and life-saving treatment. (Michael Robinson Chavez / Los Angeles Times)