The 1929–1930 psittacosis pandemic, also known as the the great parrot fever pandemic was a series of simultaneous outbreaks of psittacosis accelerated by the breeding and transportation of birds in crowded containers for trade and was initially to have originated in parrots from South America. It was shortly found to have spread from several species of birds from several countries worldwide to humans between mid 1929 and early 1930. Diagnosed by its clinical features and link to birds, it affected around 750- 800 people globally, with a mortality of 15% (death toll estimated at over 100) . Its mode of transmission to humans by mouth-to-beak contact or inhaling dried bird secretions and droppings was not known at the time. The cause was Chlamydia psittaci a bacteria which lays dormant in birds until activated by stress of capture or confinement. Cases were reported in mid 1929, in Birmingham, United Kingdom, and linked to parrots from Buenos Aires, Argentina, where an ongoing outbreak of the disease had led to the cautioning bird owners to declare their sick parrots.