By Shana Bohac
Chagas disease, also known as trypanosomiasis, is caused by a tropical protozoan parasite known as Trypanosoma cruzi and spread by a nocturnal, blood-feeding insect known as the kissing bug. The parasite is widespread among Mexico, Central America and South America.
Twenty-eight states in the United States now have established populations of kissing bugs. The highest density of kissing bugs has been found in Texas, Arkansas and New Mexico. This insect vector transmits the parasite to the host by biting and defecating near the site of the bite. Dogs can also contract the disease by ingesting the bugs or infected prey (armadillos, coyotes, mice, skunks, foxes, rats and raccoons). Transmission from mother to fetus may also occur. Sporting and working dogs, young dogs, and dogs that sleep outdoors are at higher risk than other dogs. Domestic and wild mammals can contract the parasite as well. The disease can also be spread to humans. In many underdeveloped countries, the disease is spread from human to human by blood transfusion, organ transplant, contaminated food, breast milk or from mother to fetus through the placenta.
Dogs infected with T. cruzi may present with fever, inappetence, lethargy, enlarged organs, cardiac abnormalities or sudden death. The disease frequently causes congestive heart failure. Symptoms of congestive heart failure can range from exercise intolerance and coughing to a swollen abdomen, difficulty breathing and discolored gums (gray-blue to purple). Any puppy or young dog experiencing symptoms of congestive heart failure should be tested for Chagas disease. Some dogs can be infected with T. cruzi, but show no symptoms at all.
Diagnosing Chagas disease requires a history of those symptoms listed above, a thorough physical exam, as well as bloodwork and X-rays to rule out other causes of the symptoms. A blood test can be performed to check for antibodies or exposure to the parasite. Unfortunately there is no effective treatment for Chagas disease in dogs. The focus of treatment is typically on the heart failure and arrhythmias. There are currently drug studies going on, but there is nothing approved to treat T. cruzi. Dogs with Chagas disease have a poor prognosis for survival.
The best approach for prevention and control of Chagas disease is eradication of the kissing bugs on your property. This can be very challenging, but you can start by spraying your house and surrounding property with residual insecticides. Dog kennels, cracks, crevices and rocks are an ideal environment for kissing bug infestations so these areas need to a focus of your insecticide treatment plan. You want to make sure that the product you use is safe for pets and that you follow all directions carefully. The insects are nocturnal, but are attracted to light, so turning outdoor lights off at night may also help.
If your pet is experiencing any of the signs, please consult your veterinarian. Keep an eye out for kissing bugs. If you do start noticing kissing bugs around your house, take the necessary precautions to prevent exposure to your pets.
Dr. Shana Bohac is a veterinarian at Lakeway Veterinary Clinic in Edna. She works on both small animals and equine patients. Submit questions to firstname.lastname@example.org