Beware of the kissing bug, Alberta snowbirds travelling south this winter are being advised.

They're deadly parasites that feed on people's blood when they're sleeping.

Kissing bugs, also known as 'assassin bugs,' are becoming more prevalent in the United States, having crawled their way north into at least 28 states.

The cockroach-like insect earned its name from the way it feeds. It often bites a person's face and lips while they lie quietly sleeping.

"The trick is, when you're in bed, you have the sheets pulled up," said Pete Heule, resident bug expert at the Royal Alberta Museum in Edmonton. " Even if you're in Central America, where it's really hot, you still have the sheets pulled up, and the most commonly exposed body part is your face.

"They crawl up, and more often than not they tend to bite you in the face, so they get the name 'kissing bug,' which is rather gruesome."

Although their bite is not poisonous, the bugs are carriers of a deadly parasite that causes Chagas disease.

An estimated seven to eight million people, mostly in Mexico, Central America and South America, have the disease, and the infection is becoming increasingly common in the southern United States.

Heule said it is the bug's "droppings" that are truly dangerous.

"It's actually within the guts of the bugs, so the bug biting doesn't actually inject you," he said. "But these guys drink a lot of blood, so they tend to void the contents, they defecate nearby..and it's the droppings of the bugs that contain the infection."

Chagas is not a reportable disease in Canada. But an estimated 5,000 to 10,000 people across the country are infected.

Initial symptoms are usually mild and may include fever, swollen lymph nodes, headaches or swelling. Heule said although the risk of infection is low, it can remain undetected for decades.

It can take 10 to 30 years before people begin to experience more serious symptoms, such as swollen or enlarged vital organs.

"It's considered a neglected tropical disease," Huele said. "I think the biggest factor is people going down to Central and South America and getting bit, not knowing they got bit, and then coming back here."

Huele suggests travellers do their best to avoid getting bitten in the first place. Use a mosquito net, and cover up, especially when sleeping.