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Guinea Pig Cookouts Promote Peru's Parasite Plague

Jun 29, 2015 02:05 PM EDT
guinea pig
(Photo : Pixabay)

Has a visit to the pet shop ever made your mouth water? No? Then you've clearly never had guinea pig. The cuddly rodents have been a reliable snack in parts of Ecuador, Peru, and Colombia for generations. Called cuyes in Spanish, the animals are reportedly easier to raise and breed than chickens, and are eaten en-masse during key holidays. However, it's those feasts that could be leading to an unintended consequence: a plague of parasitic bites that is bringing South America to its knees.

The Parasite Plague

Chagas disease, known as American trypanosomiasis in the medical world, is a potentially life-threatening illness caused by the protozoan parasite Trypanosoma cruzi (T. cruzi). According to the World Health Organization (WHO), a stunning seven million people are infected with the debilitating disease world-wide, with 30 percent of all chronic patients suffering from persistent heart problems and even organ failure. Another 10 percent may suffer from digestive problems after their esophagus or colon swells to an unnatural size.

Thankfully, the disease is pretty darn hard to get. Not only does the T. cruzi's main vector, a tiny insect known as the kissing bug, have to decide to make a blood-meal of person, but it also has to stick around long enough to defecate near its bite. Only scratching at that bug's 'kiss' in just the right way can push that feces into the wound, and even then, the kissing bug has to be infected with the parasite to begin with for the disease to take hold. As far as we know, only one human becomes infected with Chagas for every 1700 kissing bug bites. (Scroll to read on...)

A macro shot of the bloodsucking
(Photo : Flickr: Glenn Seplak) A macro shot of the tiny and bloodsucking "kissing bug" perched on a patch of skin.

So how the heck is South America currently suffering from what can only be described as a plague of chronic T. cruzi infections? Currently, health officials estimate that up to 40 percent of people in some communities are victims of Chagas disease - a rate that had never been observed in the estimated 9,000 years that the disease has been circulating among humans.

Gutting the Guinea

At least in Arequipa, Peru, guinea pigs may be to blame for this local plague. According to a study recently published in the Proceedings of the Royal Society B, seasonal feasts may be "bottlenecking" domestic populations of the tasty rodents, causing them to become the ideal middlemen for ensuring that most kissing bugs in a region are carrying T. cruzi.

Being small and gentle animals who reproduce at a stunning rate, guinea pigs became preferred even over chickens in South America for animal husbandry within the last couple decades. They have even been celebrated in the southern US as a new and economic alternative to cattle.

However, for small Peruvian communities, feeding these little rodents during dry summers - when alfalfa prices spike - can prove too costly. That's why most farmers will slaughter the majority of their stock save for one or two healthy breeding pairs. The resulting meat, which has been described as oily and pork-like, is then cured and saved for a great many festivals and holidays that occur during the season.(Scroll to read on...)

(Photo : Flickr: Nestor Lacle)

Unfortunately, with fewer rodents around, the remaining guinea pig populations are relatively doomed to be bit by T. cruzi infected bugs. These survivors serve as reservoirs for the parasite, spreading it back to other kissers until the great majority of the biting insects are armed with T. cruzi.

In this way, researchers theorized that they would find many-many more kissing bugs infected than usual - a change that world directly influence how frequently local humans are exposed to the disease.

And that appears to be exactly what occurred in Arequipa. After many generations of this "bottlenecking" cycle of parasite hosts, more than 80 percent of the kissing bugs taken from local guinea pig pens boasted the parasite. Comparatively, only six percent of the sample kissing bugs from rodent enclosures - where seasonal culling does not occur - carried T. cruzi.

And of course, with infected bugs abound, that one in 1700 chance we mentioned earlier drastically changes.

Still, many experts are arguing that this revelation shouldn't dissuade locals from raising guinea pigs. In fact, many groups are pushing for the animal to become a common stock even in the US. Instead, the WHO recommends that blood screening and animals tests become common place - treating and defeating the disease before it is given an opportunity to spread.

And all the while, people can keep chomping down on the cute, cuddly, and just so dang tasty.

For information on Chagas disease in the US, visit here.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).


 - follow Brian on Twitter @BS_ButNoBS


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