Guinea pigs: the phantom menace

We hasten to reassure readers. If you live at home Guinea pig, don’t worry that your furry pet one day decide to enslave humanity. Recently published in the journal Proceedings of the Royal Society B a study by researchers from the U.S. and Peru only shows the role of Guinea pigs in an abnormally high frequency of dangerous diseases in South America. Yes and that role play Guinea pigs against their will, the fault lies with parasitic insects and in humans.

The disease is called Chagas ‘ disease – in honor of the Brazilian physician Carlos Chagas (1879 – 1934), who described the disease and its causative agent contributing. Chagas was engaged in the fight against malaria. In the course of his research he discovered one-celled organism related Trypanosoma brucei – the causative agent of African sleeping sickness. He took it to the same genus and named Trypanosoma cruzi in honor of his teacher Brazilian parasitologist Oswaldo the cruise. As found by Chagas, transmitted by Triatoma infestans bugs . Rhodnius prolixus and several related species. All these bugs prefer to bite in the area of the mucous membranes, e.g. lips, so called “kissing bugs”. Chagas demonstrated in experimental monkeys the mechanism of infection, described the symptoms appeared, found the same symptoms in people in the blood which also showed trypanosomes.This is a rare case when a scientist opens a pathogen, its vector and transmission mechanism, usually this required the efforts of several researchers.

“Kissing bug” Triatoma infestans

Discovered by Carlos Chagas the disease is prevalent in several countries in Central and South America. The infection occurs not as a direct result of the bite of a bedbug, but after scratching the man from the wound of the bite. The wound fall the bug faeces, which contain the trypanosomes. After the infection begins the acute phase of the disease. It is characterized by fever, headache, shortness of breath, heart palpitations, swollen lymph nodes, pallor, muscle pain, trouble breathing, swelling and pain in the abdomen and chest. On the skin in areas of infection have specific types of lesions. Often there is swelling of the eyelids (kissing bugs love to bite not only on the lips and in the eyelids). In severe cases, there is acute heart failure, which with high probability leads to death. The acute phase can last up to three months. In the second, chronic, stage of the disease the trypanosomes are striking mainly in the myocardium and the neuro-muscular system of the digestive tract. In most patients it is asymptomatic (the patient remains a source of infection if it bites kissing bugs). Others may occur dilatation of the esophagus or parts of the intestine, increasing the ventricles, which again leads to heart failure.

The spread of Chagas disease

Annually from Chagas disease die from 10 to 12 thousand people. The discovery by Carlos Chagas bugs the vectors a recent study showed. that spread the disease and the bedbugs ( Cimex lectularius ). In nature the reservoir of the disease can be other animals, which the bedbugs bite: dogs, cats, rabbits, monkeys, pigs – in total more than 150 species.

The authors of the current research asked the question: why in some areas of South America the incidence of abnormally high. Still, the Chagas disease is not so easy to get infected, it is estimated that from 1700 the bites of kissing bugs only one leads to infection. And in Peru, there are places where infected nearly 40% of the population. Scientists in the works in one of these places, Arequipa, came to the conclusion that the reason for this in Guinea pigs.

The residents of Peru are kept at home quite a lot of Guinea pigs. Bedbugs biting them and transmitting the trypanosomes. In a large herd of pigs the number of infected individuals is small. But when the number of pigs is decreasing, the bugs, including those that carry the infection, it becomes no one to bite, and they pounce on the few remaining. As a result, the infection rate of pigs increases and subsequently increases the risk of human infection.

Periodic reduction in the number of Guinea pigs occurs regularly every year. The fact that Peruvians are bred these animals not with aesthetic purposes. From the times of the Incas Guinea pig is used as a source of meat. In the modern kitchen of Ecuador, Peru and Bolivia there are many of dishes from this rodent, fried ( chactado or frito ), boiled ( asado ) or grilled ( al horno ). Guinea pigs require less feed than cows, reproduce quickly, tolerate conditions of high mountains. Guinea pigs are served in the restaurants and eat at home, and many families, both in the city and in the villages, bred them as an additional source of income and sell in the markets.

A dish of Guinea pig

A year in Peru eat about 65 million Guinea pigs. In many places in the East, there is a special ceremony called jaca tsariy (“the gathering of pigs”). Usually it is timed to the celebration of local Catholic Saint. It reminds caroling. People go from house to house, collecting donations of Guinea pigs. Then from pigs prepare a feast. Yes and those places, where do not produce “the gathering of pigs”, they serve a traditional dish for the holidays.

As noted by the authors, especially a lot of such holidays falls in the summer months. Many Peruvians used to cook the food of Guinea pigs at the feast of the Body and blood of Christ, celebrated on Thursday after Trinity, that is, at the end of may – beginning of June. Researchers compared the cooking Guinea pigs the Peruvians with the tradition to cook Turkey on thanksgiving Day in the United States. Popular cuyadas and summer parties, barbecues Guinea pigs.

There is another reason for the decline in the number of porpoises in the summer. In Peru it happens quite regularly, dry summer. Then increase the price of alfalfa, the main food of Guinea pigs. To contain them becomes economically unprofitable, that people EN masse and send them for meat.

So, pigs eat. Bedbugs are forced to focus on a small number of remaining animals. This increases the likelihood of disease transmission. In Arequipa, the cycle was repeated from year to year. As a result, now, as discovered by the researchers, 80% of the bugs living on local Guinea pigs infected with Chagas disease, while bugs that live on other animals, infestation of only about 6 %. Unfortunately, bedbugs, biting pigs will not give up and to bite their owners, which increases the chances of Contracting Chagas disease to humans.