OVERVIEW
Interactions between people and animals can result in disease transmission. Interactions can be touching wildlife, being near wildlife, or even just living in an area with lots of wildlife. A science called 'eco-epidemiology' looks at how ecology and environment affect human and animal health. Our team studies the eco-epidemiology of Chagas disease and kissing bugs in the United States. Our research helps us learn more about how to protect people and animals from Chagas disease.
THE VECTOR — Kissing bugs
Kissing bugs feed on blood and are active mostly at night (nocturnal). Adult kissing bugs are about 1/2 to 1 inch long. Kissing bugs hatch from small eggs and go through five juvenile (nymphal) stages before they become adults. Some kinds of kissing bugs can live up to two years.
All kissing bugs feed on blood throughout their lives. Kissing bugs can feed on people, dogs, and wild animals. They feed many times over their lives. When kissing bugs feed, they can take several minutes to take a full meal. Kissing bugs do NOT attach like ticks. Kissing bug bites do not usually hurt the person while they are feeding.
Kissing bugs live throughout North America, Central America, and South America. In the United States, kissing bugs have been found in 29 states. All shaded states in the map have at least one kissing bug found there. Striped states are those from which we have received submissions to our Community Science Program. In some states, kissing bugs have only been found a few times and are probably rare. Those states are Delaware, Illinois, Indiana, New Jersey, Pennsylvania, and West Virginia.
All shaded states have at least one historical record of kissing bugs. Striped states are those from which we have received submissions to our Community Science Program. Please note that there are several states where kissing bugs have been found only once or twice and are likely rare. Map made using QGIS 3.28 using US Census state map file.
Eleven different kinds of kissing bugs are in the United States. Texas, New Mexico, and Arizona are the states with the most different species and most findings of kissing bugs. Scientists have found that about 50% of kissing bugs are infected with the Chagas parasite.
Kissing bugs are a 'vector' because they can carry a parasite that can make people and animal sick. The parasite is Trypanosoma cruzi, and it causes Chagas disease. The number of infected kissing bugs varies from location to location.
THE PARASITE — Trypanosoma cruzi
A parasite called Trypanosoma cruzi causes Chagas disease. Chagas disease can occur in people, dogs, and other mammals. The Trypanosoma cruzi parasite is sometimes called T. cruzi.
Kissing bugs can get the T. cruzi parasite from feeding on the blood of an animal or person infected with the parasite. Then kissing bugs carry the T. cruzi parasite in their guts. The parasite is in the feces of the kissing bug. The parasite is NOT in the saliva or bite of the kissing bug. If kissing bug feces enters someone's body, the parasite can infect the person and cause Chagas disease. Some kinds of kissing bugs poop while they are feeding; if a person scratches the kissing bug feces into the bite then the person may get sick. The parasite can also enter the body through the mouth or eye if someone touches their mouth or eye with a dirty hand. Dogs can become infected by eating kissing bugs.
Some kissing bugs in Central America and South America are more likely to be in houses and pass the T. cruzi parasite to people. Sometimes a mother with Chagas disease can pass the disease to her baby while she is pregnant. The parasite can be passed through blood and organ donations, and sometimes through food or drink contaminated with kissing bug feces.
PEOPLE — How we are affected
No one knows exactly how many people in the United States have Chagas disease. Scientists think that in the United States there are at least 300,000 cases of Chagas disease in people, and there may be more than 1 million cases. Most states are not required to keep track of the number of people with Chagas disease. Doctors are starting to count the number of people with Chagas disease in Texas, Arizona, Arkansas, Louisiana, Mississippi, Tennessee, Utah, and Los Angeles County.
People who live or lived in parts of Central America and South America are at higher risk of having Chagas disease. In the United States, Chagas disease risk is higher in southern states (where there are more kissing bugs) than in northern states.
Chagas disease has two stages; the first stage is called the 'acute phase' and the second stage is called the 'chronic phase'. After the T. cruzi parasite enters the body, the acute phase can last for a few weeks or months. During the acute phase, some people experience symptoms like fever, tiredness, body aches, headache, rash, diarrhea, loss of appetite, or vomiting. Some people do not notice any symptoms during the acute phase. This can make it difficult to diagnose for Chagas disease.
After the T. cruzi parasite enters the body, about 1 out of 3 people develop the chronic phase of Chagas disease. The chronic phase can take many years to develop — some people have the chronic phase for decades after the parasite enters their body. In the chronic phase, people may experience heart problems or other symptoms.
If you are concerned about Chagas disease, talk with your doctor. There are Chagas disease tests and treatments available. Doctors can work with the CDC to learn more about treatment options for a person with Chagas disease. There are currently no vaccines to protect people from Chagas disease.
WILDLIFE AND DOMESTIC ANIMALS — Impacts
The T. cruzi parasite can infect many kinds of wild animals. Kissing bugs get infected from feeding on infected wild animals, dogs, and people. In the US, wild animals that can carry the T. cruzi parasite are woodrats, raccoons, coyotes, opossums, and other mammals. Birds and reptiles cannot be infected with Chagas disease, but kissing bugs can feed on their blood. Some animals may be able to carry the parasite without getting sick.
CANINE HEALTH — Impacts
In dogs, infection with the Chagas parasite can cause heart disease. But many infected dogs may be asymptomatic (not appear sick). A dog’s daily stress and activity level along with age may affect how sick a dogs gets from Chagas disease. Different types of the Chagas parasite can also affect how sick a dog gets. Some common signs of illness in dogs are heart problems, stomach issues, and sometimes sudden death.
A dog can be tested for Chagas disease by testing a sample of blood to see if a dog has antibodies for the T. cruzi parasite. A test for dogs is available through the Texas Veterinary Medical Diagnostic Laboratory. Dogs with a positive test result may not show signs of illness. Talk with your veterinarian to learn more about the test and what a positive test means for your dog.
For dogs, there are not many Chagas disease treatments. Scientists and veterinarians are working on new treatments for Chagas disease in dogs. There is no vaccination that protects against Chagas disease.
Scientists at Texas A&M University have found Chagas disease in dogs in many counties in Texas. Other scientists have found Chagas disease in dogs in other southern states. As more owners learn about Chagas disease and test their dogs, we expect more counties to be added to the current map.
As awareness of Chagas disease grows and more cases are confirmed, we can expect many more counties to be added to the current map.
ENVIRONMENT — The importance of surroundings
The environment around a house affects Chagas disease risk to people and animals. For Chagas disease to be a risk, the environment has to have the kissing bug, the parasite, and infected animals or people.
There are steps you can take to lower the chance of Chagas disease affecting your family and animals. These steps are:
- Secure your house to keep kissing bugs from sneaking in. Plug any gaps around doors and baseboards, and fix any holes in window screens. Don't leave windows or doors open without screens.
- Keep the area under and around your house neat. Remove wild animal nests, piles of branches and wood, and trash so that wild animals stay away from your house. Wild animals can carry the parasite and also be blood sources for kissing bugs.
- Turn off outside lights at night if safe. Kissing bugs might fly towards lights and then crawl into a house. Keeping the lights off can keep the kissing bugs from coming near.
- Work with an extension agent or a pest control company to discuss integrated pest management (IPM) strategies. Information about pesticide options can be found in the Texas A&M's extension entomologist post HERE. If you use pesticides, be sure to read the label and apply only as the label says.
Dog kennels in Texas and other southern states may have problems with kissing bugs. Kissing bugs can be attracted to the heat and smells of areas with lots of dogs. Some dogs might eat kissing bugs in kennels. Keeping kissing bugs away can be difficult in kennels, especially where kennels are surrounded by natural areas with lots of wild animals. Following the tips listed above can help to keep kissing bugs away.