Recent news reports on vectors and emerging diseases have pinpointed “Kissing Bugs” as a growing threat to humans and other mammals. The amiable name belies a blood-sucking insect that can transmit a protozoan parasite known as Trypanosoma cruzi (T. cruzi), causing an incurable disease known as American Trypanosomiasis or Chagas Disease. In the past few years “kissing bugs” (triatomines and related insects) have been moving north from tropical climates.
The disease is endemic in 21 countries in South America, Central America, and Mexico, and has now spread as far north as the entire lower half of the United States (U.S.). Human and animal migration and climate change have allowed the insects to invade not only the USA but Spain, Switzerland, France, Italy, Germany, and England, where the disease has been diagnosed readily in people and in dogs.
Domesticated pigs, cats, and wildlife such as opossums, armadillos, raccoons, skunks, woodrats and non-human primates are also affected, though to what degree is not fully known. Chagas infection in dogs and people in endemic regions can range anywhere from 5% to 92%. It is considered somewhat rare in the United States - unless you fall in that 92nd percentile.
What Are Kissing Bugs?
Kissing bugs are nocturnal insects that feed on blood, not plants. They are also known as assassin bugs, cone-nose bugs, vinchuca, chinche and barbeiro and there are over 130 species of Triatomes in the Americas. They have a flat, broad back that may have a ridge of orange or red stripes along the edge; adults are less than an inch long and are wingless. Triatomes look like some other bugs that are plant eaters, but their behavior is distinctively different.
Kissing bugs that invade a home hide during the day and come out at night, attracted by the carbon dioxide (CO2) exhaled by their targets, thus their painless bites frequently are on the face, near lips or eyes (kissing). Like bedbugs, they are found in mattresses and other areas in a home and hide in rocks, wood, debris or under concrete outside. Should you find unexplained sores on your face or other body parts or find blood on your pillow, contact a professional exterminator or your doctor for more information.
What is Chagas Disease?
Reports from Texas A&M in 2011 showed that about 50% of tested kissing bugs carried the T cruzi parasite. Kissing bug nymphs and adults defecate while feeding and that is when T. cruzi is passed to the host. Scratching or rubbing the bite can transfer the parasite into the skin and from there the organism enters tissues, muscles, and cells and begins reproducing. The invaded cells eventually rupture, allowing entrance to the bloodstream where the disease sets sail for other organs, especially the heart and brain. This is known as the acute stage, a time when there may be a local reaction known Romaña's sign, localized irritation or no symptoms at all.
According to the CDC, the acute phase can last for weeks or months. It is possible to find the parasite in various blood tests during this time, a diagnosis that is very difficult in later stages. Other means of infection include entry by mucous membrane, crossing the placenta in a pregnant mammal, passage via mother's milk, ingestion of an infected animal or ingestion of the bug itself.
Following the acute phase, most infected people enter a latent stage during which few or no parasites are found in the blood. Most people are asymptomatic at this time, and thus are unaware of any problems for months or years. Of these people, 20 to 30%, including immuno-suppressed individuals, will eventually develop a chronic phase of Chagas that can cause severe medical problems. Complications may include heart rhythm issues resulting in sudden death, heart dilation that interferes with adequate pumping, megaesophagus or dilated colon causing gastrointestinal issues.
How Can Chagas Affect My Dog?
Incubation requires 5 to 42 days with sporting dogs or dogs in rural areas most at risk. During the acute phase, animals younger than six months primarily develop myocarditis and cardiac arrhythmias that can result in collapse and sudden death. Other symptoms may include fever, anorexia, lethargy, enlarged lymph nodes, diarrhea, pale gums, cough, enlarged liver or spleen, depression, anemia, bloat. Learn more about Chagas Disease in Dogs.
The latent phase of the disease may cause no symptoms at all and typically lasts around 8 months. When the disease enters the chronic phase, the heart is the most common organ affected, resulting in heart failure or sudden death. Supportive treatment of symptoms is usually indicated. Nifurtimox or Benznidazole are antiparasitic drugs used in people but they may cause serious side effects and are not always readily available for animal use. Learn more answers to the Top 5 Pet Owner Questions About The Kissing Bug.
How to Prevent Chagas Disease in Your Dog
There is currently no vaccine available against canine Chagas disease.
Prevention is the best policy. Tips for preventing Chagas disease in your dog include:
- Screen blood donations carefully for infection.
- Check breeding females for antibodies. Do not breed positive bitches.
- Screen dogs from southern states or south of the border.
- Insecticide may be used to knock down the bug population, but of course, must be used discriminately.
- Keep your dogs inside at night, or in a building that will limit access by the bugs.
- Clean up rockpiles, woodpiles, chicken coops and treat under concrete.
- Repair screens and seal cracks to the outside.
- Turn off outside lights at night.
- Fluralaner and Afoxolaner, the active ingredient in common tick prevention medications for dogs, have shown effectiveness in repelling the bugs. Comfortis® has shown limited effectiveness.
- Dog collars with deltamethrin.
- Homeopathic treatments should be carefully checked through a qualified veterinarian.
- Diseased blood can be infectious to humans, so due diligence is required with infection more likely transmitted during the acute phase of the disease.
- Suspected infestations should be treated by licensed professional exterminators.
The bugs live in the surroundings, under mattresses, dog beds, etc., not on the dog.
Can Cats Get Chagas Disease? What about Cats?
Cats can contract Chagas disease in the same manner as humans and other mammals. They are generally asymptomatic but have been noted to develop hind leg paralysis and convulsions. They may not exhibit symptoms until years after the initial infection. As mentioned above, supportive care for complications and other symptoms is traditionally given. Do not treat cats with dog parasite drugs; they cannot tolerate them.
Do I Panic Now?
No. Chagas disease is an emerging disease of concern for human populations but is still not as likely as Rabies, Distemper, Flu, Heartworm, Lyme, Anaplasmosis, Ehrlichiosis, Rocky Mountain Spotted Fever or Leptospirosis in your pets in North America. Stay informed, ask your veterinarian for advice and employ protective measures as you should for other diseases.
Vaccines and parasiticides are important tools in your protection kit, so use them to prevent the diseases that are prevalent. Your veterinarian is your best bet to keep you and your pets healthy and happy for many years. With competent veterinary care, our pets are living longer than ever before and that is a good thing!