The influenza pandemic of 1918 was an influenza epidemic of unusual severity. Unlike other epidemics of influenza that affect children and elders, many of its victims were young and healthy adults, and animals, including dogs and cats. It is considered the most devastating pandemic in human history, because in only one year it killed between 40 and 100 million people.
After registering the first cases in Europe, apparently in France, the influenza passed to Spain, a neutral country in the war and that did not censure the publication of reports on the disease and its consequences, hence, despite being an international problem, it was given this name because it seemed in the information of the time that it was the only country affected.
Although the First World War did not cause the influenza, the proximity of the barracks and the massive movements of troops helped its expansion. The researchers believe that the soldiers' immune systems were weakened by the strain of combat and chemical attacks, increasing the chances of contracting the disease.
A factor in the transmission of the disease was the amount of travel of the combatants. The modernization of transport systems made it possible for mariners to spread the pandemic more rapidly over a wider range of communities.
