Q: Is the Kissing Bug the only vector for the disease?
A: Yes, there are many different Triatoma species throughout the Americas, although they are all considered “kissing bugs”. Different species may have different behaviors that make infection more or less likely. Some of the bugs in South America defecate as soon as they feed, which places the infected feces directly near the open bite wound.
Q: Where is it common? in what countries?
A: Chagas’ disease has been found in North, Central, and South America where the reduviid bugs live. T. Cruzi can not exist without the kissing bug as the vector. It is considered endemic in South America and Mexico in humans. Recently we have been seeing a increase in canine cases in some of the southern United States as the disease travels north through Mexico (Texas, Louisiana, and California are among the states with confirmed cases).
Q: Who can get Chagas’ disease?
A: Many mammals can be infected by T. Cruzi, including, but not limited to; humans, rats, dogs, raccoons, skunks. Opossums and armadillos have also been reported to carry the disease. Wildlife can serve as an important reservoir for the disease.
Q: Why is Chagas’ disease a problem in dogs?
A: The initial infection with Trypanosoma Cruzi, can cause vague or even no clinical signs. Fever, enlarged lymph nodes, and anorexia (lack of appetite) are a few of the vague symptoms seen in the acute phase. There is also a latent phase that may last for years, where the protozoa is present in the body, but does not cause any signs of disease. The chronic infection of Chagas’ disease can cause heart disease by damaging the heart muscle and ultimately causing a heart arrhythmia and heart failure. Sudden death due to a heart arrhythmia is sometimes the only sign of the disease. To make it even more confusing, some dogs that are infected will never develop signs of the disease.
Q: Who is at risk?
A: Dogs that live outside and in wooded areas in sections of the country that have the kissing bug are most at risk. People and animals who travel to areas that are endemic for the disease also are at higher risk.
Q: Do you see Chagas’ disease often in your clinic? Is it common or rare?
A: Now that we are looking and testing more for Chagas’, we see around 2 to 3 positive cases a month. Before I graduated from vet school, 10 years ago, I was taught that I may diagnose 1 case in my professional lifetime. So although Chagas’ is not as common as heartworm disease in our practice (which we diagnose daily), it is definitely something I test and look for in certain cases.
Q: Is there a treatment for Chagas’?
A: There is no published proven “cure” for Chagas’ disease. There are some anti-protozoal treatments that have been used in humans, but are difficult to acquire and have had limited success in dogs. Treatment has been aimed at treating the symptoms of the disease, such as the heart failure. Fortunately through research, there have been some experimental treatments which are promising. I have had three canine cases so far that have proven this treatment to be successful. This research will soon be published and available by the researcher that has discovered it.
Q: How does I know if my dog has Chagas’?
A: Testing for Chagas’ disease in dogs can be done by having your veterinarian submit a blood sample to a specialized lab for further analysis. PCR (VRL lab) and IFA Antibody tests (Texas A&M Veterinary Diagnostic Lab) are both available only through your veterinarian.
Q: How do I prevent the disease?
A: There is no medicine or vaccine that can prevent the disease. Prevention is more aimed at decreasing the exposure of animals and humans to the kissing bug that harbors the disease. These bugs live in wooded areas, and are attracted to light at night. Keeping dogs inside at night and away from wooded areas, where the bug may be hiding, can help limit exposure to the disease. Certain insecticides can be used to treat areas that may serve as a habitat for the kissing bug.
Q: What about humans?
A: Transmission of Trypanosoma cruzi from dog to human has NOT been reported. Although the presence of the disease in dogs, could show that the disease is present in that region, and may indicate that humans may also be exposed.
Q: Anything else about the disease?
A: I don’t want everyone all throughout the country to worry that their dog has Chagas’ disease. Right now the disease is emerging into the United States, but it is still a rare disease in most parts of the country. I do see a lot of stray and rescue animals at my practice, and these dogs are more likely to have been exposed to the kissing bug through their prior living conditions. These animals are at higher risk, which is why I have more positive cases in my hospital.
My personal goal is to have veterinarians in certain areas of the country to now have Chagas’ disease as a possible differential diagnosis for certain patients. Earlier detection of the disease will also help improve the outcome for the patient because once the heart has been damaged, the effects are permanent. Hopefully this experimental treatment protocol will continue to be successful and this disease will not always equal a death sentence every time it is diagnosed.
My desire to help patients with this disease comes from the loss of two young dogs that were owned and loved by my personal friends. Through the frustration of losing these pets, I have learned more about this emerging disease, and now have successfully treated new patients.
Q: Is there anything you’d like to acknowledge?
A: I would also like to thank Dr. Roy Madigan of The Animal Hospital of Smithson Valley in Spring Branch, Texas for his help and for sharing his knowledge of this disease.