Blood banks put at risk by parasite

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.

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.

“It just went downhill,” she said. Russo died in June 2006.

As a result of the cases, the CDC last summer warned doctors that the prevalence of infection might be higher than previously thought, especially in areas like Los Angeles County.

Chagas is a clear reminder that “diseases don’t have geographic borders anymore,” said Dr. Suman Radhakrishna, an infectious diseases expert in Los Angeles who helped treat Russo. Doctors need to be “cognizant that diseases happening elsewhere in the world can happen in our backyard too.”

Another disease, cysticercosis, caused by tapeworm larvae, is believed to cause as many as 10% of the seizures reported to large urban emergency rooms in California and New Mexico. Dr. Ashok Jain, a USC emergency room doctor, said the figure may be as high as 20% at Los Angeles County USC Medical Center.

It is spread through ingestion, not the blood or organ supply.

“When I was in Cook County in Chicago, I didn’t even know it existed,” said Jain, an associate professor of clinical emergency medicine at USC. “Then I came to L.A. County ... and oh, God, there were so many cases.”

Diseases like Chagas and cysticercosis have emerged as an issue for some opponents of illegal immigration, who argue that exotic diseases are often spread by illegal immigrants.

“Curbing illegal entry will diminish the problem of exposure to such diseases because legal immigrants are medically screened to protect the U.S. public,” said Jack Martin, special projects director for the Federation for American Immigration Reform, an immigration control group..

Public health officials say the migration of diseases has always been an issue -- and is especially so today, in an increasingly mobile world with a global economy. Many urge caution, not alarm.

“I don’t want people to overreact, but I don’t want people to ignore it,” said Victor Tsang, chief of the immunochemistry lab at the CDC’s Division of Parasitic Diseases. “The more we pay attention to it, the better off we are.”

ron.lin@latimes.com

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Chagas disease

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Bites from an insect found in Latin America can introduce Trypanosoma cruzi parasites into the human blood stream, which can cause Chagas disease. In the U.S. it can be spread by blood transfusions and organ transplants.

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T. cruzi parasite

The one-celled parasite feeds on heart and gastrointestinal tissues.

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Triatomine insect

The insect can pass Trypomastigote parasites to human hosts when it bites.

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A million T. cruzi could fit inside a single photo pixel.

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Sources: National Institutes of Health, University of Texas at Arlington

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Chagas Q&A;

What is Chagas?

Chagas disease is an illness resulting from infection of a single-celled parasite, Trypanosoma cruzi. It is native to Mexico, Central America and South America. It is named for Carlos Chagas, the Brazilian doctor who discovered it in 1909. Some scientists hypothesize that Charles Darwin died from Chagas.

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Is it deadly?

It can be, but most people who are infected will not show symptoms. Ten percent to 30% of those infected show symptoms; as many as 10% die.

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How many people are infected with the parasite?

In Latin America, about 10 million to 12 million people are infected. In the United States, experts believe that about 100,000 people have the parasite, although most of them probably don’t know they are infected.

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How does it spread to humans?

The parasite can be generally transmitted to animals and humans through blood-sucking triatomine insects -- similar in appearance to a striped cockroach. The insects often live in the cracks of mud walls in homes or in thatched roofs. The insects transmit the parasite by defecating on a person after biting; the parasite enters the body through a skin wound or through the eyes or mouth. Insect-borne transmission is rare in the United States, but transmission can occur during a blood transfusion or an organ transplant.

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Why is it becoming a problem in the United States?

Immigrants are moving into the United States from areas in Latin America where the parasite is a problem, and American tourists also are bringing back the parasite from overseas. Because Chagas has not been seen as a significant problem in the United States until recently, there has not been widespread screening for the parasite in doctors’ offices, in the blood supply or among organ transplant donors.

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How do officials know that Chagas has become a problem?

Studies of blood donors in the L.A. area over the last decade show increasing prevalence of the parasite in the donor population.

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What are the initial symptoms?

People may or may not become ill in the first few weeks or months of being infected. Early symptoms may include fever, fatigue, body aches, headache, rash, loss of appetite, diarrhea and vomiting. These early symptoms can fade away, but the infection can still spread. Symptoms are most obvious in people with weak immune systems, such as those who have recently received organ transplants.

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What happens when the parasite lives in the body for decades?

The parasite does its worst damage in the heart’s muscle and nerve cells and the nerves of the esophagus and colon. After many years of infection, the heart can begin to fail or beat abnormally, leading to complications resulting in death. Patients could also develop gastrointestinal problems.

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What should I do if I think I have the parasite?

Go to your doctor or a specialist in infectious diseases and ask to be tested.

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How is Chagas treated?

In the early stages of infection, anti-parasitic drugs can be given to reduce the parasite to undetectable levels in blood. People showing symptoms of the disease may need pacemakers or medication to manage abnormal heartbeats or require a heart transplant.

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Sources: U.S. Centers for Disease Control and Prevention, Times reporting