Budgies and bugs: our homegrown contribution to pandemics

The psittacosis epidemic of 1929–1930, spread by the Australian budgie, provides lessons for the COVID‐19 pandemic

At a time when the world is engulfed by the coronavirus disease 2019 pandemic, it is worth looking at an outbreak to which Australia made a special contribution — the psittacosis (after the Greek word for parrot) epidemic of 1929–1930.1 An important vector for the infection was our greatest export — the budgerigar, Melopsittacus undulatus, more commonly known as the budgie, the most popular pet in the world after dogs and cats.2 In America our little feathered friend is called the shell parrot or lovebird.

It took a world‐wide epidemic to learn that budgies can carry a potentially lethal infection. Small outbreaks of psittacosis (otherwise known as parrot fever) occurred in 1879, 1890 and 1917. What had been a rare disease became a global outbreak in 1929, starting in Argentina from a shipment of Brazilian parrots.3 The first reported case was of an actor playing a sailor who caught it from his stage parrot. Bird transports were stopped and the infections disappeared, but by then the birds had been taken to other countries — out of the cage, as it were. Cases arose in Britain, Europe, North America, Australia, Japan, Iceland and Japan. The infections were carried by parrots of various breeds, chickens, ducks and turkeys, as well as the ubiquitous budgie.4

England, Argentina and Germany were the worst affected countries. In the United States, psittacosis was first identified by a Baltimore doctor who notified the Public Health Service. There were 33 deaths in 6 months, a mortality rate of almost 20% — another two deaths were of laboratory technicians.1 There was a 35% mortality rate in patients over the age of 35 years; by comparison, the 1918 influenza pandemic was fatal in 8% of cases. Sixty‐three percent of cases were older women; whether they had greater involvement with pet birds or a special vulnerability is unclear.1

Newspapers leapt on the story, churning out hair‐raising accounts of a disease that threatened to destroy the human race.5 Widespread hysteria spread through the public. Any case of pneumonia in older women was automatically assumed to be psittacosis (“old maid’s pneumonia”). The panic was fanned by bacteriologist‐turned‐writer Paul de Kruif. What medical historian Nancy Tomes called the “epidemic exposé”6 was illustrative — while described as virulent and lethal, in reality the condition was not in most cases. Added to this, the publicity fed a national germ‐phobia on which American business rapidly capitalised through mass sales of products such as disinfectants, antiseptics and tissues.5

As with every epidemic, denial soon occurred. People refused to believe that psittacosis existed or regarded it as a joke. Viennese scientist Julius Bauer thought Americans were suffering from “mass suggestion”, and that psittacosis had “assumed in the public mind the dimensions of a plague”.5 The Bird Dealers’ Association of America, which had a vested interest, insisted that the condition was merely media hype.

If there is a hero in this story, it is Swiss‐born Karl Meyer, based at the George Williams Hooper Foundation for Medical Research at the University of California, who dissected a Californian budgie to find signs of the infection.7 Meyer contracted psittacosis in 1935 by removing his gloves in the laboratory, but fortunately survived. He coined the term “ornithosis” for an illness spread by about 50 types of birds and later showed it could be cured with tetracycline.1

It gives some idea of the trade that between 310 000 and 410 000 birds were brought into the US. It took the illness of a senator’s wife to generate government action, and President Herbert Hoover banned the importation of parrots.5

Within a few years, it was realised that the infectious agent in psittacosis was not a typical virus, but it took until 1966 to discover that the organism was Chlamydia psittaci.1

Meyer’s findings were transmitted to the homeland of the budgie. Future Nobel laureate Macfarlane Burnet, based at the Walter and Eliza Hall Institute in Melbourne, found that psittacosis had been present in Australian parakeets for centuries.8 Mild infections in the wild had little effect but would flare up in close confinement and then spread easily to humans. The infection was transmitted in bird faeces, which would dessicate and become airborne. The widespread prevalence of psittacosis in Australia indicated that conditions in budgerigar breeding establishments in Europe and America were probably derived from the natural infections of the original Australian birds from which they were descended.

The final estimate for the 1929–1930 outbreak is 750–800 cases, characterised by the remarkable speed at which the infections spread.1 The epidemic was stopped by banning the importation of birds, a testimony to effective intervention at a time when our knowledge of pathogens was far more limited and antibiotics were unknown.

Although there were far fewer cases than recent pandemics, the 1929–1930 psittacosis outbreak provides lessons for today. It led to public hysteria and media panic. It posed a serious risk not only to the public but to health workers and laboratory technicians. Determined government intervention, in this case banning transport and sale of birds, stopped further spread. And, as always, a few brave and determined individuals stood out through their efforts to understand the illness.

In Australia, psittacosis is a notifiable disease, with 1687 cases reported nationally between 2001 and 2014 but very few deaths.9 All this from our favourite feathered pet, weighing no more than 35–40 g.