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Five Things to Know about Kissing Bugs and Chagas Disease

The disease-causing parasite spread by biting bugs has spread beyond the tropical world

An adult Rhodnius prolixus (kissing bug) on the right and large nymph on the left (Thierry Heger CC BY-SA 3.0 via Wikimedia Commons)
smithsonian.com

Kissing is an activity that can usually be characterized as sweet to passionate. But the "kissing bug" is anything but romantic: The insect sucks blood and can spread a parasite that causes Chagas disease. Both terms (kissing bug and Chagas disease) are probably unfamiliar to most Americans, but in light of a recent rash of the disease in Texas, they probably shouldn’t be.

Most sources label Chagas as a tropical disease, but it used to be more common in the southern U.S. and now seems to be making a comeback. Experts blame a number of factors, including climate change, for the rise of some tropical diseases in the U.S. Many doctors don’t or aren’t trained to recognize the symptoms, hastening these illnesses’ slow creep northward.

A joint investigation by Seema Yasmin of The Dallas Morning News and Scott Friedman and Eva Parks of NBC5 explores what it means when a disease creeps unnoticed into the population, using the example of Chagas disease in Texas. The full report is worth reading, but here are some quick facts on the disease:

The Disease Is a Parasite Infection

Chagas disease is spread by the nocturnal, blood-sucking kissing bug, also called Rhodnius prolixus. These insects tend to bite sleeping people on the thin skin near their mouths, leaving a bite wound that earns them their nickname.  Unfortunately, the bugs also defecate on the source of their meal. These feces can enter the wound when a person scratches or rubs their face, and if the bug was infected with a parasite called Trypanosoma cruzi, infection with Chagas disease can follow. 

The insects themselves seem to have genetic modifications that modify it’s immune system to tolerate the parasite, according to new research published in Proceedings of the National Academy of Sciences. The parasite can also hitch a ride in blood transfusions, from a mother to her fetus or, rarely, if someone eats raw food (like fruit) that has been contaminated by the insect or parasite. 

Not Everyone Shows Symptoms

During the first few months after a bite, only mild symptoms crop up, and these are hard to pin on Chagas—fever, fatigue, body aches, loss of appetite, diarrhea and vomiting. The most distinctive sign is a swelling of the eyelids on the side of the face that was bitten. But there can be no signs at all. Very rarely, young children can die of infection of the heart or brain at this stage. After about 8 to 12 weeks, only about 30 percent will develop chronic Chagas disease. For some this can lead to worse symptoms like heart failure or even cardiac arrest, decades after their initial infection. 

Keep the Numbers in Mind

The risk of picking up Chagas is still low in the U.S.—the Centers for Disease Control and Prevention estimates just 300,000 people in the nation carry the parasite responsible for the disease. But because people can be unknowing carriers for decades, estimated prevalence is hard. The risk is slightly higher in Texas where "one in every 6,500 blood donors are infected with Chagas disease, compared with one in every 27,500 donors across the country," the reporters write for The Dallas Morning News and NBC5

Even so, the disease is a very real concern for many in tropical countries. The World Health Organization estimates 6 to 7 million people are infected worldwide, most in Latin America, but The Chagas Disease Foundation puts that number as high as 20 million. (For comparison, there were about 214 million cases of malaria in 2015.) 

The Disease Isn’t New

In 1909, Brazilian physician and epidemiologist Carlos Justiniano Ribeiro Chagas first described a parasite he found in the intestines of people living in a rural area of the Amazon. He also found that large insects the same genus as kissing bugs could give monkeys the parasite by biting. (The disease is probably much older than that: Researchers have found that a 9,000-year-old Chinchorro mummy carried the parasite.) Yet it wasn't until 1966 that researchers developed the first treatments.

There Is Treatment

Two medicines (benznidazole and nifurtimox​) are almost 100 percent effective in curing the disease if its caught in the first stage, according to WHO. However, there is no vaccine to prevent infection. Screening blood donors, spraying houses, using bed nets as well as attention to hygiene are the best ways to prevent Chagas disease.

H/T Juliana Barrera at Latin Times

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