In the context of a retrospective investigation about the various outbreaks occurred in Portugal during the first half of the twentieth century (bubonic plague, epidemic typhus, smallpox and pneumonic influenza), the author analyzes in this paper the problem of the bubonic plague.Official statistics provide data on the plague only for the period 1930-1949, period of time when this nosological entity persisted only in the Azores, which will be the subject of this study. The Azores islands suffered outbreaks in 1931 and 1932, which entered an endemic phase, and ended with deaths from the plague in 1950.The author analyzes the occurrence of the plague in the Azores addressing the following parameters: the epidemic’s evolution over the years, distribution of deaths by gender, age groups, months of the year and affected districts.

The epidemic diseases that devastated the European populations added to the miseries that existed until the mid-nineteenth century, causing considerable loss of human life. The European continent has a long history of plague, a disease caused by the Y. pestis bacteria. Contrary to popular belief, bubonic plague is not a disease of the past. It is still present in more than a dozen countries around the world. This paper analyzes Jules Héricourt's ideas regarding the international transmissibility of epidemic diseases and how to mitigate their chains. It is essentially based on his work Les Frontières de la Maladie, namely on Défense internationale contre les maladies épidémiques, et systémes quarantenaires. In 1901, an outbreak of plague ravaged the passengers and crew of the ship Senegal on a Mediterranean cruise. A quarantine was imposed on the entire crew and 174 passengers in the lazaretto in the French archipelago of Frioul. There was one death. The lack of minimum services and immediate disinfection measures for passengers and their belongings could have exacerbated the problem. Héricourt, physician, co-author of the serotherapy, disagrees with the methods adopted by health authorities, which would be illusory in the international defense against epidemic diseases. The author proposes a practical and effective double solution to the problem of the transmission of exotic diseases in sea voyages: the enhancement of the health pass and the modification of the role of the doctor on board. All passengers from contaminated territories should carry a health pass, under strict control by the authorities. The on-board doctor is responsible for establishing himself as a true agent of the health administration. As a hygienist, he unmasks potential patients, based on medical examinations during the trip, and prevents passengers who are considered healthy from contaminating the community, as they are effectively ill.

The black plague appeared in the 14th century in Europe by the bacterium Yersinia pestis transmitted by fleas and black rat (Rattus rattus) , moreover the spread of this disease was very quickly through silk and spices trade routes. The high rate of contagion and mortality led many people to rely on religion, because they believed it would save themselves. At the time, as scientific knowledge about this type of diseases was scarce, the population believed in a relationship between medicine and religion, considering the Black Death as a divine punishment for the sins creating a serious social problem. Over the course of history, the Catholic Church may have been a limiting factor in the development of scientific knowledge. Ignorance and unreasonable faith led to serious consequences, such as, the persecution and murder of innocents in the name of the faith, thus being responsible for a high number of deaths in the Middle Ages for encouraging the elimination of Jews in Europe, as a need for redeem themselves for their sins. In this text, we intend to present the main contributions to the development of knowledge about this pathology as well its relationship with religion, the theories disseminated by the Church and the people's blind belief in them to obtain God's forgiveness. Religion can be an obstacle to scientific knowledge, preventing the advance of Science, in addition to leading people to commit wrong and perverse attitudes to achieve their objectives.