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In the latest issue of PLoS Neglected Tropical Diseases, a distinguished group of virologists, epidemiologists and infectious-disease specialists say that’s not necessarily a hypothetical question. They passionately argue that Chagas disease, a parasitic infection transmitted by blood-sucking insects, has become so widespread and serious — while remaining largely unrecognized — that it more than deserves to be considered a public health emergency.
The earth’s climate is changing and it’s doing so more rapidly than any of the scientists originally predicted. What was once “100 years from now” has become “now.” Researchers are reporting entire species, such as the long-beaked Triatoma or “kissing bug” moving northward, away from the ever increasing southern heat, and some of those species aren’t friendly toward us or our pets, so we best be prepared.
Chagas disease is a condition caused by infection with the protozoal parasite Trypanosoma cruzi and it has always been a big problem for our neighbors to the south. The U.S. Centers for Disease Control (CDC) says that it is “endemic throughout much of Mexico, Central America, and South America, where an estimated 8 million people are infected.”
Lest one think the he United States has been immune to Chagas disease, however, it should be noted the CDC “estimates that more than 300,000 persons with Trypanosoma cruzi infection live in the United States” but that most of these people “acquired their infections in endemic countries.”
As a result of a warming climate the range of the disease is spreading northward into the United States and is becoming increasingly important for two primary reasons: it affects many different species but most notably dogs and people.
The parasite that causes Chagas disease is transmitted by triatomine bugs, more commonly called “kissing bugs.” Unlike many other types of vector-borne diseases, the bite of a kissing bug is not responsible by itself for transmission but when a kissing bug bites a person, dog, or other mammal, it tends to defecate at the same time. The bite causes the victim to scratch, and that activity pushes the nearby feces and the parasites it contains into the wound caused by the bite itself. Dogs can also become infected with T. cruzi by eating infected bugs or prey, or the disease can be passed congenitally from a mother to her offspring.
The symptoms of Chagas disease in dogs vary with the duration of infection:
Acutely infected dogs typically have a fever, loss of appetite, lethargy, swollen lymph nodes, and an enlarged liver and/or spleen. This phase may go unnoticed by owners, particularly since the clinical signs tend to resolve with time.
Dogs have no symptoms at all in the latent phase, which may last for several years.
With chronic infection, however, dogs can develop a type of heart disease called dilated cardiomyopathy. This may result in congestive heart failure or more shockingly, affected dogs may drop dead before developing any symptoms of heart disease.
Sad to say, no medications have been found to effectively treat Chagas disease in dogs. Symptomatic treatment for dilated cardiomyopathy and congestive heart failure can help dogs feel better and live longer than they would otherwise, but the underlying problem remains and it’s going to get worse. A vaccine is also not available, so prevention is limited to practices that minimize a dog’s exposure to kissing bugs and other sources of infection with T. cruzi.
The Veterinary Medicine and Biomedical Sciences program at Texas A&M (Texas is a Chagas disease hotspot) makes the following recommendations:
Prevent dogs from eating bugs
House dogs indoors at night
Prevent dogs from eating potentially infected animals (mice, rats, etc.)
Test breeding females to prevent congenital transmission
They also state that “although direct transmission from dogs to humans has not been reported, infection in dogs indicates the local presence of infected vectors, which may present an increased risk of vector borne transmission to humans.”
For more information on Chagas disease in people click to see the CDC’s website.
Research:CDC, Wired.com, PetMD