Also called 'American Trypanosmiasis', Chagas disease is caused by a blood-borne, protozoal (i.e. single celled) parasite called Trypanosoma cruzi. Chagas disease is primarily seen in Latin American countries, but in recent years it has been migrating north into the United States. It has been found in several states, including Texas, Louisiana, Oklahoma, New Mexico, California, Florida, Georgia, North & South Carolina, Virginia, Tennessee, and Maryland. It is a disease process that can affect a number of animals, but most notably it affects dogs and people.
How Do Dogs Get Chagas Disease?
T. cruzi is spread by Triatominae bugs. Insects belonging to this subfamily are also called kissing bugs, kissing beetles, conenose bugs, assassin bugs, and even vampire bugs. As a term like 'vampire bug' may infer, these are blood-sucking bugs. They often live in areas where finding a blood meal would be relatively easy. This includes kennels, bedding materials in barns, and sometimes even our own homes. Unfortunately kissing bugs don't really follow the life motto not to poop where you eat because when a beetle containing the T. cruzi organism takes a blood meal it simultaneously (and disgustingly) defecates. If a dog scratches at the bite site and gets the bug's fecal material in the wound or if a dog licks at the bite site and ingests fecal material, he can become infected with the parasite. Less commonly, the parasite can also be passed from a mother to her offspring.
Symptoms of Chagas Disease
The clinical signs of Chagas disease are variable and non-specific. Most infected dogs demonstrate subtle signs, such as lethargy, decreased appetite, and weight loss. In more severe cases, you may also notice more severe signs, such as fainting, exercise intolerance, vomiting, and diarrhea. If your dog becomes infected by T. cruzi there are three unique stages of infection with three unique sets of clinical signs:
- Acute Phase: This phase occurs within a few weeks of infection. In some cases, there may be no clinical signs during the acute phase of infection. If your dog does exhibit symptoms during this phase, they may include lymph node enlargement, spleen enlargement (this is due to your dog's body trying to fight off the infections), pale gums (stemming from poor circulation), a decreased appetite, and diarrhea. Some infected dogs may die suddenly during this phase of infection, however most will enter the latent phase.
- Latent Phase: This phase is typically asymptomatic and lasts 1-4 months. An infected dog may die suddenly during this phase, but most will enter the chronic phase.
- Chronic Phase: That final phase of infection will see T. cruzi organisms continue to replicate and as they do they will migrate to various organs but mainly target your dog's heart and brain tissue. This results in clinical signs that include symptoms commonly seen in dogs with heart disease. Symptoms such as coughing, exercise intolerance, shortness of breath, heart arrhythmia, and even sudden death.
Although Chagas disease isn't zoonotic in the true sense like leptospirosis (in which you can contract the disease directly from your already infected dog), it is an infection that people can also get from Triatominae bugs. If your dog becomes infected with Chagas disease, it indicates the presence of T. cruzi in your local environment and that your yourself may be at risk for infection.
Diagnosing Chagas Disease in Your Dog
During the acute phase, T. cruzi may be found in the blood or lymph nodes of your dog, but they are typically present in such low numbers that a reliable diagnosis cannot be made. In the chronic phase, however, Chagas disease can be diagnosed by it's clinical symptoms.
Treating Chagas Disease in Your Dog
Unfortunately, there is no curative treatment for Chagas disease in dogs. Once your dog reaches the chronic phase, his symptoms may be supportively managed with heart medications. The best treatment, however is prevention. Keep your dog indoors at night, where they can sleep in clean bedding. Preventing your dog from eating potentially infected bugs and animals (including skunks, raccoons, and opossums) can also keep your dog T. cruzi free. If you live in an area with a high population of kissing bugs, you may also use pesticides in your yard to help control the population but ensure that it is a pet safe pesticide before you spray. Keeping wood piles away from the home and inaccessible to your dog while they are outside and keeping outdoor kennels or dog houses away from brush and wood piles can also minimize your dog's exposure to these bugs.
If you live in a southern state and are concerned about Chagas disease and your dog's risk for contracting it, speak to your veterinarian for more information on what to look out for and how you can protect your pup and yourself.