Latin immigrants raise parasite risk

The rising migration of Latin people to the United States increases the potential number of cases of a deadly parasitic infectious disease, common in the Southern Hemisphere, that is spread by blood transfusions.

Seven persons are known to have been infected with the largely incurable illness, known as Chagas disease, through blood transfusions in the United States and Canada since 1986, five of them in this country

The American Red Cross estimates that, nationally, the risk of a blood donor having antibodies to Chagas or being infected with the disease is 1 in 25,000. The same risk is 1 in 5,400 in Los Angeles and 1 in 9,000 in Miami.

Dr. Louis V. Kirchhoff, a professor at the University of Iowa’s medical school, and a Chagas specialist, said the risk of contracting the disease is growing fast because of immigration. He noted that U.S. Census data show that net immigration from Mexico alone is about 1,000 people a day, and that as many as 10 percent are probably infected.

The Red Cross plans to begin screening blood donors for Chagas disease when a suitable test is found. “The best-case scenario is that this will take a couple of years” to find a test that the U.S. Food and Drug Administration will approve, said Red Cross spokesman David Leiby.

“An estimated 15 million South Americans [plus Mexicans and Central Americans] are suffering from Chagas disease. I’m amazed more cases have not turned up in our blood supply,” said Dr. Arthur C. Aufderheide of the University of Minnesota School of Medicine in Duluth during a telephone interview.

Mr. Leiby said the five cases in which people were infected through the U.S. blood supply ?? most recently in 2002 in Rhode Island and in 1999 in Miami ?? “are just the cases we know about.” Some of those people have died.

“There have probably been more cases that have not been reported or were not recognized,” he said.

In fact, the Red Cross estimates that nationwide as many as 618 blood donations yearly could contain Chagas antibodies, thus be “potentially infectious,” said Mr. Leiby.

Chagas is a disease that causes a high fever, enlarged lymph nodes and can permanently damage vital organs, most often the heart.

Especially threatening, said Dr. Aufderheide, is the fact that people “can live for decades” with a chronic form of Chagas.

During this phase, he said, victims may look and feel all right. “And they think they are fit to donate blood,” when they really aren’t.

“We need to have a test” to screen blood for Chagas, said Dr. Hira Nakhasi, director of transfusion-transmitted diseases at the U.S. Food and Drug Administration.

Blood transfusions are just one of the ways in which Chagas is transmitted, Mr. Leiby said. It’s also spread through the feces of a family of blood-sucking insects found in this country, as well as through mother-to child infection and organ transplants.

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