Answer and Explanation:
There are many physical elements such as temperature, precipitation, humidity, altitude, vegetation, among others, that influence the presence of the insects that transmit the Chagas diseases. Its transmission seems to be enhanced by other social elements, such as the deficiency in basic services, lack of planning, the socio-economical conditions, cultural conditions. Altogether, these factors intervene in the presence of the Chagas disease, a systemic infection caused by the protozoa <em>Trypanosoma cruzi</em>. This protozoan is hosted by different wild and domestic mammals, transmitted to the human by hematophagous insects. The transmission occurs through dejections deposited on skin or mucose during or after the feeding process.
Different rural areas in Central and South America are characterized by a mountain relief (temperatures between 15 and 30ºC - relative humidity between 50 and 90%), as well as by a plane relief associated with alluvial plain (temperature between 20 and 35ºC - media relative humidity of 75%). Vegetation in the mountain area provides a natural habitat to the triatomines, the insects that transmit the Chagas disease.
Constant deforestation in mountains, soil move, the cutting down, firing, have destroyed the natural habitat of the insects, becomming the cause of their arrival to populated centers. As their environment is destroyed, insects migrate to new areas and find refuge in precarious houses that surround the affected areas. Most of these houses have clay walls, a roof made of branches, and no floor. People that live in these conditions do not have economic resources. Indexes of infestation in these houses are high due to the material used for their construction. Insects tend to establish near a source of food, such as domestic animals or even humans. It is also common that these houses have chicken coops and farmyards that also offer good conditions for the insects to live in.
Economic activities are important variables to consider, as these define the way of living in a population.
Agriculture activities are performed with no control or planning. People deforest to plant, getting in contact with the insects' natural habitat, producing environmental changes, and getting in touch with them, enhancing the risks of being infected and of transportin the insects.
