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Report: Undiagnosed Chagas Disease Emerging as U.S. Public Health Threat

Meeting presentations highlight treatment gap

Across the southern U.S., residents face a tangible but mostly unrecognized risk of contracting Chagas disease — a parasitic infection that can lead to severe heart disease and death — according to new research presented November 4 at the American Society of Tropical Medicine and Hygiene (ASTMH) annual meeting, held in New Orleans, Louisiana.

Chagas disease (American trypanosomiasis) is typically spread to people through the feces of blood-sucking triatomine bugs, sometimes called “kissing bugs” because they feed on people’s faces during the night. The disease, which can also be spread through the blood supply, affects 7 to 8 million people worldwide and can be cured –– if it is caught early.

Often considered a problem only in Mexico, Central America, and South America, Chagas disease is being seen in Texas and is being recognized at higher levels than previously believed, according to researchers at Baylor College of Medicine in Houston. Among those infected are a high percentage believed to have contracted the disease within the U.S. border, according to the scientists, whose findings will be published in the American Journal of Tropical Medicine and Hygiene.

While the new research was conducted in Texas, kissing bugs are found across half of the U.S., according to the Centers for Disease Control and Prevention (CDC). Bites from these insects may be infecting people who are never diagnosed because of a lack of awareness of Chagas disease by health care personnel and the U.S. health care system, the researchers say.

The authors previously conducted an analysis of routine testing of Texas blood donors for Chagas between 2008 and 2012. In that study, published in the August 2014 issue of Epidemiology and Infection, the authors found that 1 in every 6,500 blood donors tested positive for exposure to the parasite that causes Chagas disease. That figure is 50 times higher than the CDC’s estimated infection rate of one in 300,000 nationally.

“We think of Chagas disease as a silent killer,” said co-author Dr. Melissa Nolan Garcia, an epidemiologist at Baylor. “People don’t normally feel sick, so they don’t seek medical care, but it ultimately ends up causing heart disease in about 30 percent of those who are infected.”

Symptoms can range from non-existent to severe, with fever, fatigue, body aches, and serious cardiac and intestinal complications. In the U.S., positive blood donors could cost about $3.8 million for health care and lost wages for those individuals, according to the researchers’ calculations. In addition, according to a recent study published in Lancet Infectious Diseases, societal and health care costs for each infected person in the U.S. average $91,531.

Another presentation at the ASTMH meeting showed that people who test positive for Chagas disease mostly go untreated. Jennifer Manne-Goehler, MD, a clinical fellow at Harvard Medical School, collected data from the CDC and from the American Association of Blood Banks and compared the approximately 2,000 people who tested positive through the blood-banking system with the 422 doses of medications administered by the CDC from 2007 to 2013.

“This highlights an enormous treatment gap,” Manne-Goehler said. “In some of the areas of the country we know there are a lot of positive blood donors, yet people still don’t get care. We don’t know what happens to them because there is no follow up.”

In the U.S., most physicians are unfamiliar with Chagas disease, and some who have heard of it mistakenly dismiss the disease as a not-so-serious health concern, even in parts of the country where many people may have Chagas symptoms, Manne-Goehler said. Further complicating the situation, currently available medications used to treat Chagas disease in the U.S. have not been approved by the FDA. Physicians seeking treatment for their patients are referred to the CDC, which offers two drugs, nifurtimox and benznidazole, both of which carry the risk of adverse effects, including nausea, weight loss, and possible nerve damage.

Manne-Goehler called for the creation of an independent expert panel to define clinical screening guidelines to help improve the identification of patients with Chagas disease in the U.S. In addition, she argued for the creation of a physician-referral network so that physicians who are unfamiliar with Chagas can send patients to providers who regularly diagnose and treat the disease.

Source: MedicalXpress; November 4, 2014.

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