Investigators tested nearly 5,000 Latin American-born residents of Los Angeles County in California.
They found that 1.3 percent had Chagas disease, which can cause life-threatening heart damage if not treated early.
"Less than 1 percent with the infection are receiving treatment for Chagas disease," said study author Sheba Meymandi.
Meymandi is director of the Center of Excellence for Chagas Disease at Olive View-University of California, Los Angeles Medical Center.
Chagas disease is caused by a parasite called Trypanosoma cruzi, which is transmitted by the triatomine bug - also called the "kissing bug" - found throughout the Americas.
About 30 percent of infected people develop serious heart, digestive or neurological disorders, the researchers said in background notes.
The new study suggests there are about 30,000 people in the Los Angeles area with Chagas. It also supports a U.S. Centers for Disease Control and Prevention estimate that about 300,000 people in the United States are living with Chagas disease, the investigators said.
"Without treatment, many Chagas patients are at risk of a "silent death" due to heart failure.
"Our study demonstrates the need for similar research in other states, and underscores the critical importance of early detection and treatment to tackle this public health challenge in the U.S.," Meymandi said in a news release from the Drugs for Neglected Diseases Initiative.
"Although this study concentrated on Latin American-born residents of Los Angeles, Chagas disease has also been in the U.S. for centuries," said Colin Forsyth, an epidemiologist from the Drugs for Neglected Diseases Initiative and Doctors Without Borders.
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