The rise of Chagas disease in the U.S., and how it’s here to stay
In this DML Report…
Chagas disease, caused by the parasite Trypanosoma cruzi, is transmitted primarily through the feces of triatomine bugs, known as "kissing bugs," which bite humans and animals at night and leave infected waste that can be accidentally ingested or absorbed through the skin or mucous membranes. These bugs, measuring 0.5 to 1.25 inches long, hide in dark home areas like wall cracks and ceilings during the day before emerging to feed on blood. Originally a tropical illness confined to Latin America, the disease has become endemic in the United States since its first detection in Texas in 1955, with human cases now reported in eight states and the bugs found in 32 states. Factors contributing to its spread include deforestation, human migration, and climate change effects like warmer temperatures and increased rainfall that expand bug breeding grounds. In the US, an estimated 300,000 people across states including California, Texas, and Florida are infected, though up to 80 percent remain asymptomatic and unaware, per CDC data; California alone accounts for 70,000 to 100,000 cases, largely due to its large Latin American-born population, particularly in Los Angeles.
The disease progresses in two phases: an acute phase in the first weeks or months after infection, featuring symptoms such as fever, fatigue, body aches, rash, loss of appetite, diarrhea, vomiting, and Romaña's sign—swelling, redness, and inflammation of the eyelid near the bite site where the parasite multiplies. Most cases then enter a chronic phase lasting years or a lifetime, during which the majority experience no symptoms, but 20 to 30 percent develop severe complications from parasite-induced inflammation damaging heart muscle cells (myocytes), leading to an enlarged heart, heart failure, irregular rhythms, blood clots causing strokes, and scar tissue that impairs pumping and electrical signals. Gastrointestinal issues arise as inflammation destroys nerve cells in the enteric nervous system, resulting in enlarged esophagus or colon, difficulty swallowing or passing stool, malnutrition, and potential intestinal blockages. Often called a "silent killer," Chagas evades detection for decades, with mild early symptoms frequently mistaken for flu or colds, and US death counts remain unclear but likely low according to the CDC.
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Diagnosis relies on blood tests to detect the parasite or antibodies, though it is not closely tracked in the US, leading to underreporting. Treatment involves FDA-approved antiparasitic drugs benznidazole and nifurtimox (Lampit), which are most effective in the acute phase to kill the parasite and prevent progression, but no vaccines exist and chronic damage cannot be reversed. Prevention focuses on avoiding bug bites in endemic areas through insecticide use, sealing home cracks, and screening blood donations or organ transplants from at-risk individuals, as transmission can also occur congenitally, via contaminated food, or through lab accidents. Experts from the University of Florida and the Center of Excellence for Chagas Disease emphasize early detection and vector control to mitigate risks, particularly for travelers or residents in southern states where the bugs thrive.