What is Chagas Disease?
Cats do not usually manifest symptoms but they can be a carrier of T.cruzi, and when bitten by a kissing bug, transmit the organism to other animals, including humans, causing Chagas disease. In humans, Chagas disease can be very serious and life-threatening. There is no cure for Chagas disease, only treatment and management for symptoms.
Chagas disease, also called American Trypanosomiasis, is a life-threatening disease caused by the single-celled protozoan parasite, Trypanosoma cruzi, which is common in South and Central America. The parasite is relatively rare in the United States although cases in the southern states have occurred. Trypanosoma cruzi (T. cruzi) is transmitted through kissing bugs (triatomine bugs), which feed on the blood of mammals much like mosquitos. Kissing bugs carry T.cruzi larvae, which can be transmitted to an animal when the kissing bug feeds and the parasite enters the host. The organism T. cruzi divides and disrupts the cells of its host.
Symptoms of Chagas Disease in Cats
Most cats infected with T. cruzi are asymptomatic and do not manifest signs of Chagas disease, but can be carriers. When they do, however, symptoms in felines have been noted to include hind leg paralysis and convulsions. Many animals, including cats, do not exhibit symptoms until years after they have been initially infected.
Causes of Chagas Disease in Cats
Chagas disease is caused by the single-celled protozoan parasite Trypanosoma cruzi (T. cruzi), that is common in South and Central America, but rare in the United States where it has only been detected in the southern states. The method of transmission in kissing bugs is as follows:
- Kissing bugs carry T. cruzi larvae, which go through several life cycle stages in the bug.
- Kissing bugs bite mammals; they are called kissing bugs because they often bite the faces of their victims, although they may bite other parts of the body as well.
- The bug defecates when it bites, and when the animal or human scratches or rubs the area, feces left by the bug contaminate the bite lesion, mouth, ears, nose or eyes, allowing T. cruzi present in the kissing bug’s feces to enter the host animal.
- Once inside the mammal, the organism T. cruzi enters the host mammal’s tissues, muscles, and cells and begins reproducing.
- This causes damage to the invaded cells which then rupture, allowing T. cruzi organisms to enter the bloodstream.
- Once in the bloodstream of an infected animal, the organism can spread to other parts of the body, repeating this process and causing Chagas disease.
- They also can be taken up again by kissing bugs through bites to repeat the cycle.
In addition, the parasite T. cruzi can cross the placenta in a pregnant mammal or be passed through mother’s milk to an infected mammal’s offspring. Other methods of transmission occur when an animal eats an infected animal or by eating the infected kissing bug.
Diagnosis of Chagas Disease in Cats
Your veterinarian will do a physical examination and specifically ask the pet owner questions about possible exposure to kissing bugs. Residence or travel to an area where infection from kissing bugs was likely to occur should be reported to your veterinarian.
There are serological tests available to aid in the diagnosis of Chagas disease and urine and blood samples will be taken to employ these tests and also rule out other diseases. X-rays and ultrasounds may be ordered to determine the extent of heart and tissue abnormalities caused by the Chagas disease.
Chagas disease can be hard to diagnose as there are only small numbers of the parasitic organism causing it in the blood. However, a thick blood smear on a slide examined under a microscope may reveal the parasites. Another method is to take samples of lymph node cells and examine them under a microscope to reveal the presence of the parasite.
Sometimes, T. cruzi parasites are discovered postmortem in the heart tissue of an infected animal.
A different method used to reveal the presence of T. cruzi parasite is to feed kissing bugs the tissue of an animal that may have been infected, and then kill the bug and examine its digestive system for T. cruzi .
Treatment of Chagas Disease in Cats
There is no cure for Chagas disease and the presence of T. cruzi organisms in a host animal poses an extreme health risk to people and other animals, so euthanasia is often recommended.
There has been some success with medication used for treatment of Chagas disease (Benznidazole is one that has had some effect at disrupting the disease's progression), but resistance to the medication has occurred in many cases.
Treatment usually consists of supportive treatment for heart complications and other symptoms.
Recovery of Chagas Disease in Cats
As no cure is available, and an infected animal poses a health risk to others as a carrier, prognosis is poor and euthanasia is usually recommended. The best way to prevent infection with Chagas disease is to eliminate kissing bugs from you and your pet's environment. This can be difficult as these bugs are small and hide in cracks and crevices. You can mitigate exposure by using pesticides to kill bugs, having your pets sleep indoors at night, and sealing cracks in your home that might allow the bugs access.
