The most recent H1N1 swine flu pandemic has attracted notice to the question of how to improve our immune host defense system against communicable viral diseases.

It has often been claimed that a healthy lifestyle could be protective against infectious diseases. In fact, several lines of evidence indicate that factors such as the choice of nutrients, regular physical exercise, and reduction of stress or sleep deprivation may be protective in terms of reduced morbidity or mortality from infections.

However, the effect of lifestyle on the immune system may differ from country to country and depends on factors such as socioeconomic status and most of all the pathogenicity and the mode of transmission of viral or bacterial infections. The factors related to Chagas infections in South America, for ...