In the quiet hours of night, an unassuming insect crawls from cracks in walls or kennel bedding. The “kissing bug” — a triatomine insect — seeks blood, not affection. As it feeds, it defecates near the wound, leaving behind a microscopic invader called Trypanosoma cruzi. When a dog licks or scratches the bite, the parasite slips inside, beginning a disease cycle that can destroy the heart from within.
Once confined to Latin America, Chagas disease is now spreading across the southern United States, silently endangering pets and people alike, New Atlas reports.
Chagas disease is caused by the parasite Trypanosoma cruzi.
How Infection Spreads
Dogs can become infected through contact with the insect’s feces, by consuming infected bugs or wild animals, or from contaminated food sources. Triatomine insects are now found in 32 U.S. states, especially in Texas, Louisiana, and Arizona, and are drawn to lights, woodpiles, and kennels, according to Today’s Veterinary Practice.
Once inside a dog’s body, the parasite infiltrates cells lining blood vessels, muscles, and organs. As it multiplies, these cells burst, releasing more parasites into the bloodstream and leaving behind inflammation and tissue damage. As VCA Hospitals reports, working dogs and outdoor pets face the greatest exposure risk, though any dog living near infected vectors can fall ill.
Kissing bugs transmit the parasite through feces near bite wounds.
Silent Stages and Subtle Signs
The disease progresses in three stages: acute, latent, and chronic. During the early acute phase, most dogs show few or no symptoms. When signs do appear, they may include fever, pale gums, diarrhea, or swollen lymph nodes. This phase often goes unnoticed.
In the latent stage, the parasite hides deep within tissues. Dogs may appear healthy for months while the infection quietly advances.
The chronic phase is the most devastating. The parasite attacks the heart, causing arrhythmias, heart enlargement, and eventually heart failure. Owners may notice coughing, weakness, shortness of breath, or collapse. Sudden death is tragically common in dogs with advanced disease, according to Veterinary Medical and Surgical Group–OC.
The disease is increasingly recognized across the southern United States.
Diagnosis and Challenges
Because symptoms mimic other cardiac conditions, diagnosis is difficult. Blood smears, antibody tests, or polymerase chain reaction (PCR) assays may detect the parasite or its genetic material. According to Today’s Veterinary Practice, infected heart tissue examined postmortem often reveals the telltale amastigote cysts that confirm Chagas disease.
New testing methods, such as PCR-based vector-borne disease panels, allow earlier detection even when parasite levels are low, reports New Atlas. Still, there is no single definitive test, and many infections go undiagnosed until heart damage is irreversible.
Night lighting and brush piles increase the presence of kissing bugs and the risk of Chagas disease.
Treatment and Prevention
There is no vaccine for Chagas disease, and no guaranteed cure. According to VCA Hospitals, antiparasitic drugs like benznidazole and ravuconazole may help in the earliest stages, but their effectiveness diminishes once the infection becomes chronic. Treatment usually focuses on managing heart complications through medications that stabilize rhythm and reduce fluid buildup.
Prevention remains the most effective defense. Keeping dogs indoors at night, sealing cracks in walls, cleaning up brush or wood piles, and turning off outdoor lights that attract insects can reduce risk. The use of insecticides or deltamethrin collars can help kill vectors before transmission occurs, International Journal of Molecular Sciences reports.
Sudden death can be the first sign in some dogs.
A One Health Wake-Up Call
Chagas disease exemplifies the deep connection between animal and human health. Dogs often serve as sentinels, alerting communities to infections circulating nearby. As cases rise in non-endemic areas, veterinarians and physicians alike stress awareness, testing, and collaboration.
“We share this environment,” one public health veterinarian told New Atlas. “The more we learn together, the more we can protect both people and pets.”
Click below to make a difference.
