The Great Pox, or Venus' Pox, Syphillis is a sexually transmitted disease originating from Leifia/Tawantinland. In a continent free from plague since the 750s it caused a large degree of unrest in medieval Europe as well as continuing to be a menace to modern health.
It was first recorded in 1284 during the War of the Limburg Succession though could be traced to the movements of an Icelandic mercenary unit, who had campaigned for Vinland in Leifia the previous summer. Contracted by Anglia to besiege fortresses in Cologne. But had their camp raided and camp followers (who included many native Leifians and Tawantinlanders) defiled by a German mercenary company attached to the Brabant army. From there the infection became embedded within the armies and outbreaks generally followed in their wake. Due to this historic link it is often referred to as the 'Icelandic Disease' in Luxembourg and the Empire. It is thought that the different climate and density of population in Europe compared to Tawantinland caused the disease to mutate quickly, becoming horrifically fatal.During its first outbreak in the 1280s the disease in its original form caused pustules to spread across the body, leading to flesh falling away from faces and was fatal within months.
The disease spread quickly through the cities of the Low Countries, down the Rhineland and into North Italy, whereupon it spread rapidly around the Mediterranean. The blame that fell on the few remaining Cathar communities in Aragon's nominal territory led to their final destruction and Aragon's confiscation of land from the counts of Toulouse, building their crown lands north of the Pyrenees. The death of several high ranking members of the Hapsburg family is believed to have severely hampered the dynasty's and Austria's fortunes. In the Baltic the association the disease had with sailors led to tight state restrictions on shipping, killing off the trading towns as independent entities and building the wealth of Viken, Denmark and Svealand.
After the initial outbreak a less destructive form took over and it became largely non-fatal (at least to adults) but endemic within the European population. By the 1350s however the cultural memory of the 'Great Pox' had been completely and utterly eclipsed by the horrors of the Black Death. The initial outbreak of the Great Pox is believed to have killed some 2 million people perhaps 2% of the population of Europe whilst the Black Death killed somewhere between 30% to 60% of the population.
It is now known to be caused by a bacteria but a cure is still out of reach.