A little-known but potentially deadly parasite from Latin America has become one of the latest threats to the blood and organ supplies in the United States, especially in Los Angeles, where many donors have traveled to affected countries, health officials say.
Last year, two heart transplant patients at different Los Angeles hospitals contracted the parasitic disease, called Chagas, causing health authorities to issue a national bulletin. Within months, both patients subsequently died, although not directly from Chagas, according to the U.S. Centers for Disease Control and Prevention.
The parasite, which is generally passed to humans from a blood-sucking insect that looks like a striped cockroach, can feed over years on tissues of the heart and gastrointestinal tract. After decades, tissues can be eroded so much that the organs fail.
Insect transmission of the parasite in the United States is rare, but public health and blood bank officials have been concerned about its increasing prevalence in the blood supply.
For The Record
Los Angeles Times Saturday March 17, 2007 Home Edition Main News Part A Page 2 National Desk 2 inches; 80 words Type of Material: Correction
Chagas disease: An article in Thursday's California section about a potentially deadly parasite threatening the U.S. blood and organ supply said that HIV, which blood banks screen for, shows up in one of every 30,000 blood donors. In fact, HIV shows up in one of every 30,000 first-time blood donors; among all donors, including repeat donors who have previously tested negative for HIV and are thus less likely to be infected, the virus is found in one in every 300,000.
For The Record
Los Angeles Times Friday April 06, 2007 Home Edition Main News Part A Page 2 National Desk 1 inches; 64 words Type of Material: Correction
Deadly parasite: An article in the March 17 California section about a potentially deadly parasite threatening the U.S. blood and organ supply stated that no organ donors in the United States were being screened for the parasite, which causes a disease called Chagas. The organ procurement agency for Georgia, Florida and Puerto Rico has been screening for the parasite in some donors since 2002.
In 1996, using an experimental test, the American Red Cross found that one in 9,850 blood donors in the L.A. area tested positive for the parasite, Trypanosoma cruzi. Two years later, it was one in every 5,400. By 2006, a more refined test detected the parasite in one in 3,800 donors. About 10% to 30% of infected people develop symptoms of chronic disease, experts say.
By contrast, HIV, which blood banks screen for, shows up in one of every 30,000 donors, said Susan Stramer, executive scientific officer for the Red Cross.
If caught early, strong anti-protozoal drugs such as nifurtimox can bring the parasite to undetectable levels or, in some cases, eliminate it entirely.
If the parasite is given the chance to multiply over years or decades, however, those infected may have to be treated with heart-regulating drugs or get a pacemaker or heart transplant.
The U.S. Food and Drug Administration approved a test suitable for widespread screening in December. Blood banks have now begun systematically checking their supplies for the Chagas parasite.
By late January, the American Red Cross and Phoenix-based Blood Systems, which collect about 65% of the U.S. blood supply, had started screening blood for T. cruzi. Other banks, including the Blood Bank of San Bernardino and Riverside Counties, have no immediate plans for screening but are monitoring test results from banks that are using the test. In late February, the CDC reported that the "FDA is expected to recommend implementation of the test by all blood-collection establishments."
No organ donors in the United States are now being screened for the parasite, although the organ procurement agency that covers much of Southern California plans to begin testing some donors in mid-April. At first, the screening will be focused on people who have lived in or traveled to rural parts of Latin America, said Thomas Mone, chief executive of the agency, OneLegacy.
In Latin America, about 10 million to 12 million people are believed to be infected with the Chagas parasite. As many as 1 million of them are expected to die from the disease unless there are advances in treatment, according to Dr. James Maguire, a University of Maryland expert on the disease.
"Chagas is very, very prevalent in South and Central America," said Marek Nowicki, a USC blood-disease expert who studied the effect of Chagas on the Southern California organ supply with the National Institute of Transplantation.
"The number of [immigrant] Latinos in Southern California, Texas and other parts of the United States are growing, but especially in L.A., a large proportion of organ donors are Latino," Nowicki said. "They're basically bringing with them the disease prevalence in the area they used to live."
The problem is not limited to immigrants. Tourists, too, can be carriers. The heart transplant cases in Los Angeles last year illustrate the problem.
One donor was a native of El Salvador living in Los Angeles, and the other was born in the U.S. but had traveled to Guadalajara, Mexico, where T. cruzi is endemic.
Richard Edward Russo, then 73, received the heart from the Salvadoran native. The Burbank retiree appeared to be recovering nicely last year when, several weeks after his transplant at St. Vincent Medical Center in Los Angeles, he developed a fever and a rash. He complained of being tired and couldn't eat or walk.
About the same time, a 64-year-old man developed similar symptoms after receiving a transplant at UCLA Medical Center. He had received the heart from the American tourist.
At both hospitals, doctors submitted the patients to a battery of tests, concluding separately that they had Chagas.
The CDC sent anti-parasitic medication out from Atlanta. The drug reduced the parasite in the blood of both men to undetectable levels. But Russo never got better, his wife, Carolyn, said. He suffered from other hospital-acquired infections and had pneumonia at least twice.