Library Update: Goodbye Kiss
Triatomine bugs, also known as kissing bugs, are a growing public health concern here in the U.S. as potential spreaders of Chagas disease
Laura Rosenwald, MS, BCE, Associate Director, Education & Training, NPMA
Triatomine bugs are one of the more concerning public health pests on the horizon, thanks to their expanding range due to increases in global temperatures. More commonly known as kissing bugs or conenose bugs, these pests are vectors of Trypanosoma cruzi, a parasite that is the causative agent of Chagas disease. These insects are members of the subfamily Triatominae within the family Reduviidae—which also hosts assassin bugs—in the order Hemiptera, commonly called true bugs.
DISTRIBUTION
More than 140 described species of triatomine bugs are found around the world, but this subfamily is generally restricted to North and South America, with a few outliers in India and Southeast Asia. In the U.S., as of this publication, 11 species of triatomines—one of them rare—have been documented in 29 states, but the bugs are most common in the southern parts of the country.
IDENTIFICATION
Triatomine bugs generally measure between 12 and 27 millimeters long and are either dark brown or black, with a smooth appearance on their pronotums and heads. They often feature orange or yellow stripes around the edges of their abdomens, extending just past their wings. However, some species may be completely brown. The “cone-nosed” shape of their heads, along with the straight and thin mouthparts, can also be a key feature of identification. All six legs will appear slender. The forewings are leathery, while the hind wings are more membranous, and the wings will fold on top of each other. Note that many lookalike bugs are commonly found in the U.S., but the above characteristics are key features for triatomine bug identification.
BIOLOGY AND BEHAVIOR
Triatomine bugs go through incomplete, or hemimetabolous, metamorphosis. They undergo five nymphal stages, and the nymphs do not possess wings. Triatomine bugs develop wings when they reach the adult stage, and they are capable of short distances of flight. The lifespan and length of the life cycle of triatomine bugs differ depending on species and environmental factors such as food availability, humidity, temperature, and more. However, some species may live up to two years.
Triatomine bugs are hematophagous throughout their life cycle, meaning that they begin feeding on blood as soon as they hatch from their eggs. Triatomine bugs do not attach like ticks when they feed, but rather pierce the skin of their hosts with their proboscis. They prefer to feed around the eyes and mouths of their food sources, which is where their common name, kissing bugs, originates. It may take a few minutes for the triatomine bug to become fully engorged, and they generally will feed every four to nine days. Like bed bugs, they prefer to be active at night, when their food sources are more easily available, but may adjust their schedules to be in line with the host’s resting period. Triatomine bugs may feed on several different vertebrate species, including reptiles, birds, and mammals.
These bugs are generally the most active in the summer months from May through September but can survive for months without a blood meal. In their search for a food source, triatomine bugs are known to be attracted to light, heat, and carbon dioxide. A recent study has shown that triatomine bugs are often drawn to an area through pheromones released in the feces of other triatomine bugs, but that their reaction to the aggregation pheromone may be dictated by whether they are infected with T. cruzi.
Triatomine bugs enjoy congregating and wedging themselves in dark cracks and crevices near their food sources. They can be grouped by their habitat and host preferences: sylvatic, peridomestic, and domestic. Sylvatic triatomine bugs seek shelter and food sources in rodent burrows and bird nests. This group will also frequently find shelter in natural cracks and crevices such as caves, fallen trees, and palm fronds. Peridomestic triatomine bugs depend on domestic animals for their food sources. They may congregate around dog kennels, chicken coops, barns, and other areas where domestic animals are easily accessible. Domestic triatomine bugs are almost exclusively associated with humans and their pets and can commonly seek shelter in human establishments or kennels.
MEDICAL RELEVANCE
Trypanosoma cruzi is a protozoan parasite that is vectored by triatomine bugs. This parasite is the causative agent of American trypanosomiasis, more commonly known as Chagas disease.
T. cruzi is transmitted by triatomine bugs through their feces. From the feces, T. cruzi can be passed to the host via accidental ingestion, through mucous membranes (such as the eyes, nose, and mouth), or via deposits in the open wounds created by feeding. In addition, there are documented cases of mothers transferring the T. cruzi infection to their children in utero.
Several animals can act as reservoir hosts for this parasite, including horses, cats, rodents, and raccoons. However, dogs and humans are the only known hosts that can show signs of disease. In humans, the infection may have two phases: an acute phase and a chronic phase. The acute phase can be difficult to recognize, as it can either present with no symptoms or with symptoms including fever, body aches, gastrointestinal issues, and headaches, which are common in many diseases.
Symptoms in the acute phase may last a few weeks to months. In some cases, the acute phase may include distinctive swelling at the bite site, which can indicate a T. cruzi infection.
One in three people infected with T. cruzi will develop the chronic phase. This phase often does not see symptoms appear until years after the exposure to the parasite and can include chronic cardiovascular or gastrointestinal complications.
As of this publication, current worldwide estimates of T. cruzi infections in humans are at 6 million to 7 million, with the majority concentrated in Latin and South America. The incidence of infection is often correlated with poor housing construction or proximity to the bugs’ feeding sources, such as domestic animals or areas with other wildlife nesting.
Estimates of T. cruzi infections in the U.S. published in 2022 indicated that 288,000 people are currently infected, with around 10,000 of those infections acquired in the U.S. itself. A 2018 study surveyed more than 1,500 triatomines across several species found in the U.S. (with a focus on Texas), and 54.4% of those bugs were infected with T. cruzi.
If you believe that you or your clients have been exposed to triatomine bugs and suspect symptoms of Chagas disease, consult a medical professional.
MANAGEMENT
Management of a triatomine bug population will decrease the transmission potential of T. cruzi. Most cases of infection occur because of open opportunities for the bugs to access a host. As such, a thorough inspection will be necessary to determine where the triatomine bugs are not only aggregating, but also entering the structure to access their food source. Be sure to wear the proper PPE, such as nitrile gloves and safety glasses, when performing an inspection for a suspected infestation of triatomine bugs. Again, the T. cruzi parasite is passed on through the bugs’ feces, and transmission can occur through a variety of pathways. Minimize direct contact with these insects when possible, and wash your hands after inspections and treatments. Be sure to consult a health care provider for any suspected symptoms of Chagas disease if you have been exposed to triatomine bug feces.
In your inspection, be sure to note any potential harborage or food sources surrounding the structure. While they have their host preferences, triatomine bugs have the potential to feed on a variety of hosts. Wildlife, including rodents and birds, can serve as a food source for triatomine bugs. Removal of all wildlife harborages within 100 feet of the structure is advisable. This includes clearing away firewood piles, accumulated yard waste and brush piles, and keeping the landscape well managed.
Removal of adult bugs can be carefully done with a vacuum, provided a HEPA filter is used to prevent the potential spread of the T. cruzi parasite. Concentrate the vacuuming on areas of aggregation, which can include cracks, crevices, drapes, and bedding. Dispose of the vacuum contents properly when finished.
Exclusion tactics such as sealing cracks and crevices, repairing or replacing screens, and repairing holes in attics and ceilings can be extremely effective in preventing the triatomine bugs from entering a structure. Changing exterior lighting can help avoid attracting triatomines as well as other pests to the structure. In addition, specific human behavior patterns—such as bringing in pets, closing doors and windows at night, and performing regular inspections for new populations—can assist in controlling triatomine bug populations.
Chemical methods may also be used with triatomine bug infestations, but be sure to follow all label instructions. As of this publication, there are no pesticides specifically labeled for triatomine bugs in the U.S., but synthetic pyrethroids are commonly used in Latin America. Concentrate the application on areas of harborage, such as cracks and crevices.
If you have a suspected triatomine bug and would like to submit a sample for testing, please visit Texas A&M’s community science program website on triatomine bugs and Chagas disease, kissingbug.tamu.edu.
References
Krinsky, William L. 2002. Medical and Veterinary Entomology, “Chapter 5: True Bugs (Hemiptera).” Pg. 69-79. Elsevier Science.
Gorla, David and Noireau, François. 2010. American Trypanosomiasis Chagas Disease, “Chapter 9: Geographic Distribution of Triatominae Vectors in America.” Pg. 209-231. DOI: 10.1016/B978-0-12-384876-5.00009-5
Alaves-Rosas, David, Gutiérrez-Cabrera, Ana E., Cruz-López, Leopoldo, and Córdoba-Aguilar, Alex. 2024. “Lessons to be popular: the chemical basis of aggregation in Trypanosoma cruzi-infected and non-infected Chagasic bugs.” Royal Society Open Science. Volume 11, Issue 2.
Irish, Amanda, Whitman, Jeffrey D., Clark, Eva H., Marcus, Rachel, and Bern, Caryn. 2022. “Updated Estimates and Mapping for Prevalence of Chagas Disease Among Adults, United States.” Emerging Infectious Disease. July 28 (7): 1313-1320.
Curtis-Robles, Rachel, Auckland, Lisa D., Snowden, Karen F., Hamer, Gabriel L., and Hamer, Sarah A. 2018. “Analysis of over 1500 triatomine vectors from across the US, predominantly Texas, for Trypanosoma cruzi infection and discrete typing units.” Infection, Genetics and Evolution. Volume 58, pg. 171-180.
“Chagas disease (American trypanosomiasis).” World Health Organization. who.int/health-topics/chagas-disease#tab=tab_1.
“Parasites – American Trypanosomiasis (also known as Chagas Disease).” Centers for Disease Control. cdc.gov/parasites/chagas/gen_info/vectors/index.html.
“Kissing Bugs & Chagas Disease in the United States – A Community Science Project.” Texas A&M University. kissingbug.tamu.edu.
