Triatoma sanguisuga is known to carry that parasite that causes Chagas disease. Photo Courtesy: James Gathany, CDC.

A kissing bug may sound cute, but these members of the Reduviid family of insects can carry a not-so-sweet disease that's expected to make its way from South America into the United States, a fact scientists say is inevitable because of climate change.

Kissing bugs—whose name stems from the fact that they tend to latch on and bite human victims around the mouth—carry Chagas disease, a parasite-borne ailment characterized in its acute stage by enlarged lymph nodes, fever, eye swelling, and an enlarged liver and spleen. If left untreated for several decades, it can lead to heart and digestive diseases. In fact, it's believed that Charles Darwin may have been bitten by kissing bugs during his explorations and suffered from Chagas disease.

Previously, scientists thought that kissing bugs in the U.S. did not feed on humans as much as they do in South and Central America, where the mud-hut living conditions seemed more conducive to contact with the bugs compared to typical American housing.

But in a new study published in the Center for Disease Control and Prevention's Emerging Infectious Diseases journal, U.S. researchers analyzed kissing bugs found in California and Arizona found that nearly 40 percent had recently fed on humans. Looking at the bugs containing human blood, about half harbored Trypanosoma cruzi, the parasite that causes Chagas disease.

"The basic message is that the bug is out there, and it's feeding on humans, and carries the parasite," says study author Lori Stevens, PhD, professor of biology at University of Vermont. "So there may be greater potential for humans to have the disease in the United States than previously thought."

So far, little of that potential has been realized. Only seven cases of Chagas disease transmitted by kissing bugs have been documented in the United States. The ailment can be treated with anti-parasitic meds.

There have only been seven documented cases of Chagas disease in the United States, but this new study suggests that while transmission rates seem to be low, there may be more undetected cases in the United States than was previously thought.

If climate change patterns continue as predicted, kissing bugs are expected to migrate farther north within the United States. "We know the bugs are already across the bottom two-thirds of the U.S., so the bugs are here, the parasites are here," Stevens says. "Very likely, with climate change they will shift further north and the range of some species will extend."

Kissing bugs are nothing to spend too much time worrying about, although if you're living or camping in areas where they are prevalent, you can use these easy tips to avoid attracting them:

Turn the lights out. Kissing bugs are drawn to lights at night and can easily maneuver under doors and into your bed or your pet's. To keep them out of your room, where their "kiss" could lead to not just Chagas, but also an allergic reaction, sleep in the dark.

Camp smart. If you're camping in the southern sections of the country where kissing bugs are more common, opt for a tent with screens, and make sure you close them at night.