A zoonotic disease is one that can be transmitted from animals to people. Psittacosis is a zoonotic disease that can be passed from parrots to people. Budgerigars are parrots. By the time of the outbreak, they were well on their way to becoming the most popular pet on the planet.
The link between caged birds and human contagion was made 50 years before that fateful day in 1929 that Mrs Lillian Martin of Annapolis, Maryland excitedly lifted the cover off a gift from her husband to find an ex-parrot. Five days later she fell gravely ill herself.
Swiss physician Jakob Ritter had more than the usual medical motivation to want to get to the bottom of a household epidemic that broke out in Uster, in the canton of Zürich, in 1879: the house affected belonged to his family. Within a few short weeks, three of seven people who had sickened, including his beloved bird-loving eldest brother Heinrich, were dead.