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How a Kissing Bug Becomes a Balloon Full of Your Blood

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A kissing bug gorges on your blood. Then it poops on you. And that poop might contain the parasite that causes Chagas disease, which can be deadly. Without knowing it, millions of people have gotten the parasite in Latin America, where these insects live in many rural homes. As if that wasn’t bad enough, the saliva of some kissing bugs in the U.S. can give you a dangerous allergic reaction.


This kissing bug isn’t going to give you a loving peck when it sticks you with that tucked-away proboscis.

It could actually make you really sick, even kill you.

It makes its move at night, while you’re sleeping. It likes your warm body.

Kissing bugs get their name because they often bite near the lips or eyes, but they’ll dig in anywhere you’ve left uncovered. A little anesthetic guarantees you won’t wake up while they feed on you for 10, 20, even 30 minutes.


Every kissing bug needs several huge meals during the year or two it lives.

As it gulps, its exoskeleton stretches like a balloon, to fit up to 12 times its weight in blood. This pliability is called plasticization. How it started. How it’s going.

All that hot liquid could stress an insect’s body and stunt its growth. So the kissing bug cools it down – inside its head. Your warm blood flows in. The cool insect blood, called hemolymph, absorbs the heat and releases it through the top of the bug’s long head.

In this infrared video, you can see the blood cool down by more than 10 degrees Fahrenheit before it reaches the bug’s abdomen.

So the bug is safe. You, on the other hand, are not.

It injects saliva as it sucks your blood.

Here’s a scientist squeezing some out. The saliva has proteins that can give people a deadly allergic reaction called anaphylaxis.

And it gets much, much worse.

OK. This is super gross. After eating – sometimes while it’s eating – the bug poops. And that poop – and urine – might contain the parasite that causes Chagas disease. If the bug’s victim rubs these feces and urine into the bite wound or their eyes, the parasite can infect them. Years later, as many as one third of the people who got the parasite develop heart disease that can kill them, sometimes suddenly. Pregnant women can even pass the parasite onto their babies.

Few contract the parasite in the U.S., even though kissing bugs live here.

But in Latin America, millions of people have become infected. There, kissing bugs are known by many different names: chinche besucona … chinche … pito … vinchuca … barbeiro. In rural areas, these kissing bug species live in people’s homes, in the cracks of the walls. And in animal coops. Spraying has helped bring down infections. But hundreds of thousands of people have left their home countries for the U.S., not knowing the bug gave them the parasite. A simple blood test can find it and medications can often kill it.

In the American Southwest, the bugs live in the nests of wild animals, like this pack rat den in Arizona, where biologists Anita and Chuck Kristensen collect them.

Chuck Kristensen (off camera): Kissing bug, kissing bug! Genuine kissing bug.

For the most part, they feed on the pack rats. But in late spring and summer, the bugs sometimes travel from these nests into someone’s home.

So sealing off your house, with screens on your windows – and even vents – is one way to keep out these stealthy bloodsuckers.

Hey Deep Peeps! Wading through medical information is so overwhelming. Enter PBS Vitals, a brand new health and wellness show. Registered nurse Sheena Williams and Dr. Alok Patel answer your questions with humor, integrity and heart. Link in the description. Tell them Deep Look sent you.


Kissing bugs in the US

In California, kissing bugs – also known as conenose bugs – are most prevalent in the foothill areas surrounding the Central Valley and in the foothills and desert areas of Southern California. Find out how you can keep kissing bugs out of your house from the UC Integrated Pest Management Program.

Entomologists at Texas A&M University have put together a website with photos of kissing bugs and a map showing where they live in the U.S.

Testing for Chagas disease

Most people with Chagas became infected with the parasite in rural areas of Mexico, Central America and South America. The disease is regularly transmitted in 21 countries, among them Guatemala, El Salvador, Honduras, Nicaragua, Colombia, Venezuela, Bolivia, Argentina, Paraguay and Brazil. Transmission doesn’t occur in the Caribbean.

In the U.S., where kissing bugs very rarely transmit Chagas, researchers estimate that some 350,000 Latin American immigrants contracted the parasite in their home countries.

A blood test can find the parasite and two medications, nifurtimox and benznidazole, can often kill it.

“Any immigrants from Latin America should probably be tested at least once,” said Dr. Caryn Bern, who studies Chagas at UCSF. She said that any health care provider can order a screening test through their usual lab system.

Since pregnant women can pass the parasite onto their babies, women from Latin America or whose own mothers grew up there should get tested. Bern recommended that women test before they become pregnant because these medications can’t be taken during pregnancy.

Starting in 2007, nearly all blood banks in the U.S. started screening blood donations for the parasite.

The Center of Excellence for Chagas Disease at the Olive View-UCLA Medical Center in Sylmar, near Los Angeles, has additional guidelines on who should be tested for the parasite and offers care.

The Pan American Health Organization has information on the disease in Latin America.

The U.S. Centers for Disease Control and Prevention (CDC) has information on Chagas disease in the U.S.

Here’s a list of doctors around the U.S. who have experience treating Chagas.

And for health care providers – and anyone else – who would like to learn more, the CDC offers an online course.

Health care providers with questions can contact the CDC for consultation on all aspects of Chagas disease: Division of Parasitic Diseases Public Inquiries line, 404-718-4745; for emergencies after business hours, 770-488-7100; email parasites@cdc.gov.

Mal de Chagas

La Organización Panamericana de la Salud creó un video de dos minutos en español sobre cómo se propaga el mal de Chagas en Latinoamérica. Y también tiene información sobre la enfermedad.

Kissing bug bites can cause anaphylaxis


A recent University of Arizona study in Tucson and Bisbee, where kissing bugs commonly enter homes in the summer, found that 10% of people who had been bitten by the bugs had developed anaphylaxis, a severe allergic reaction brought on by proteins in the bugs’ saliva. Symptoms include difficulty breathing, which can cause death if the patient isn’t treated right away with medication.

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