By Eva Briggs
A patient recently was concerned about an insect pest that I’d learned about in medical school but hadn’t thought about since. While out for a walk, a flying insect landed on her arm, stung or bit her, then flew away. She caught a glimpse of something red and black, googled, and soon worried that she had been bitten by a kissing bug.
These insects belong to a subfamily called Tratominae and have a host of other common names: reduviid bugs, conenose bugs, assassin bugs and vampire bugs. In Latin America they may be called barbeiros, vinchucas, pitos or chinches.
Eleven species of kissing bugs live in the United States, mostly in the south, though they’ve been reported as far north as Pennsylvania.
The name kissing bug refers to their habit of biting the face near the eyes and mouth.
So what’s the big deal about getting bitten by a kissing bug?
At least 50 percent of the bugs harbor “Trypanosoma cruzi.” This protozoan parasite causes Chagas disease. The initial infection, or acute phase, encompasses the first few weeks of infection. Often there are no symptoms, or symptoms so mild that they’re overlooked and unrecognized.
Symptoms, when present, include fever, fatigue, body aches and rash. The patient might have a local swelling, called a chagoma, where the parasite entered the body. Romaña’s sign is swelling of the eyelids on the side of the face near the kissing bug bite. Patients can also have swollen glands and an enlarged liver or spleen. Even without treatment, the initial symptoms fade in weeks or months.
But the trypanosome remains in the body. It may exist for decades without notice during the chronic phase.
About 30 percent of chronically-infected people eventually develop complications affecting the heart or intestinal tract. Cardiac symptoms are enlarged heart, heart failure, heart rhythm abnormalities, or even cardiac arrest.
Intestinal symptoms include a massively dilated esophagus (megaesophagus) that makes swallowing difficult, or enlargement of the colon (megacolon) interfering with stool passage.
Probably 8 million people in Mexico, Central America, and South America have Chagas disease, and most don’t know they are infected. Perhaps 300,000 people in the U.S. have Chagas disease, mostly acquired in other countries. The infection doesn’t come directly from the insect bite, but from insect feces containing trypanosomes. Rubbing the insect bite can inoculate the bite with trypanosomes, or can spread them to the mucus membranes of the eye or mouth. Chagas disease can be passed from an infected mother to her baby, or acquired from blood transfusions.
The disease is diagnosed by a blood test. There are two medicines for treatment, benznidizole and nifurtimox. In U.S. both are available only through the Centers for Disease Control.
Back to my patient, is it likely that she was bitten by a kissing bug? No, for several reasons. First, Central New York is far enough north to be outside, or at best on the fringes, of the kissing bug’s range. Second, these insects live in dark cracks and crevices, often found in substandard housing. They crawl out at night and feed. So an insect flying around during the day probably is not a kissing bug.
But it was a red and black bug so what else could it be? It turns out that there are many similar critters: wheel bugs, the western corsair, the leaf-footed bug and may more.
Texas A&M University has a web page with photos of 17 insects that have been confused with kissing bugs.
So, we don’t have to worry about kissing bugs here — at least not yet.
Eva Briggs is a medical doctor who works at two urgent care centers (Central Square and Fulton) operated by Oswego Health.