An investigation carried out by the University of Sao Paulo in Brazil concludes that the indigenous people of the Amazon are resistant to the Chagas parasite, because they have genetic mutations that give them protection against infection.
Although it was already known that these aboriginal peoples were resistant to infection, the research clarifies that the reason is that they have undergone adaptations in their DNA for a long time, which blocks the pathogen that causes the pathology from entering cells, says the study published in the journal Science.
Experts believe that this step is important to better understand the disease, considering that until now there is no vaccine to eradicate it.
The study consisted of seeing how the parasite that causes Chagas disease called Trypanosoma cruzi responded. To do this, they used two DNA samples from the indigenous people, one had the mutation and the other did not. After one day, in the culture that had the mutation, the pathogens decreased by 25%.
"We saw a 25% reduction in the load of parasites that managed to enter cardiac cells with the adapted PPP3CA gene," said Tábita Hünemeier, who is the project leader.
In addition, the scientists evaluated the genome of 118 people from 19 native communities in the Amazon, and compared them with other peoples from the Americas and Asia.
In this regard, the results indicate that these populations that have lived in the Amazon jungle have variations in three genes that guarantee greater resistance to Chagas disease.
Genes
In an interview with Últimas Noticias, Saúl Villasmil Bastidas, molecular biologist and geneticist, head of the biochemistry chair at the Luis Razetti School of Medicine of the Central University of Venezuela, explained that the general conditions of the jungles provide vectors for the transmission of many tropical diseases.
For evolution, the fact that there are selective pressures and that they allow adaptation are clear evidence of how the environment is capable of guiding natural selection on a set of genes that have been studied and are related to the infection generated by the virus. Trypanosoma cruzi, the cause of Chagas disease.
Bastidas added that genetic adaptation does not depend on a single gene, on the contrary, in this type of case genes related to metabolic and cardiovascular traits, as well as the immune system, play a role in adaptation.
Among the different genes that are associated with a lower risk of developing the disease are PPP3CA and DYNC11, which are suggestively linked to seropositivity in the immune response against T. Cruzi.
Of these, PPP3CA is the one that has been found in Amazonian populations and is related to an important biochemical cascade, since it codes for the catalytic subunit of a protein phosphatase that plays an important role in immune cells.
The most affected is the heart, therefore, the reduction in the expression of this molecule from the PPP3CA gene, leads to hypothesize that the conclusion of the study is affirmative, since when inherited it provides an adaptation to the inhabitants of the Amazon jungle, protecting them of developing Chagas.
The illness
Chagas is a parasitic, systemic, chronic condition, transmitted by vectors and caused by the Trypanosoma cruzi protozoan, the Pan American Health Organization reports on its website. It is endemic in 21 American countries.
The pathogen that causes it is transmitted by the bite of insects called bedbugs, but also by transfusion and organ or oral transplants, as well as congenitally.
Experts say that the disease can be brief, acute or chronic, therefore, the symptoms range from mild to severe such as swelling, fever, rash, nausea, swollen glands and others.
In the chronic stage, it can take between 10 and 20 years, although in some cases it does not manifest itself. The signs are usually heart failure, cardiac arrest and irregular heartbeat, constipation and more.
Data
Endemic. Chagas disease is endemic in parts of the Americas, but it has increasingly been detected in countries in Europe, Africa, the Eastern Mediterranean, and the Western Pacific. It currently affects some 6 million people and another 70 million are at risk of becoming infected, indicates the Pan American Health Organization.
Treatment. Although there is still no vaccine against this infection, it can be cured if it is treated in its early stages with the drugs Benznidazole and Nifurtimox.
Strategy. Through PAHO, the countries receive between 3.000 and 4.000 Nifurtimox per year and Benznidazole can be purchased through the PAHO Strategic Fund.