Chagas disease may be making new headlines, but it’s been around for a long time. Discovered in 1909 by Brazilian physician Carlos Chagas, the tripanosomes – the microscopic organisms that cause the disease – have existed since before the continents separated. Cases in the southern United States have been documented for decades, though new areas are beginning to harbor the insect carriers, and lately there has been concern not just for humans contracting the disease, but dogs as well.
Dogs seem to be getting it from eating the triatomine – also called kissing or conenose – bugs that carry the protozoan. Most of them are pets who live and/or sleep outside, near brush piles or stacks of wood, with a light that stays on at night. The bugs hide in crevices in wood, and are attracted to light, especially white light. The little boogers are blood-suckers, who generally bite several times in an area and then defecate, and it is the feces that carry the disease-causing protozoan. The bites are itchy, and so the infected feces get scratched into the wounds, or, in humans, are sleepily rubbed into eyes or noses.
Prevention is once again easier than the cure. In fact once the disease has progressed to the chronic phase, it cannot be cured. Dogs in the early phase may display lack of appetite, weakness, fever, swollen lymph nodes, swelling of the liver or spleen, and even sometimes early heart disease. Later they may develop cardiomyopathy, where the heart muscle weakens and the chambers balloon to abnormal size. Pregnant dogs can pass the disease to unborn puppies, which can be fatal. Long-term prognosis for dogs is usually guarded, with no cure, and treatment aimed at sustaining the weakened heart and general supportive care. There is no vaccine, and while transmission from dogs to humans doesn’t appear to have occurred, the increase in infection rate in dogs indicates an increased presence of the protozoan in the insect population, which could lead to greater exposure to humans as well.
It’s best to clear brush piles and keep pet beds and kennels away from stacks of firewood, and out from under lights that may attract the triatomine bugs. Remove rodent nests within 300 feet of the house, and consider changing outdoor bulbs to yellow. Make sure weather-stripping and caulk around doors and windows provides a tight seal, repair window screens if they are damaged, and use caulk or silicone seal to close off any cracks or crevices.
There are two species of conenose bugs here in northern California that carry the parasite: the western bloodsucking conenose bug, Triatoma protracta, and the conenose bug, Triatoma rubida. The western corsair looks similar, but has an orange spot on each wing – corsairs bite but don’t carry the Chagas parasite. Conenose bugs usually bite at night, and in late spring to early summer.