Psittacosis Outbreak among Workers at Chicken Slaughter Plants, Virginia and Georgia, USA, 2018.

During August-October, 2018, an outbreak of severe respiratory illness was reported among poultry slaughter plant workers in Virginia and Georgia, USA. A multiorganizational team investigated the cause and extent of illness, determined that the illness was psittacosis, and evaluated and recommended controls for health hazards in the workplace to prevent additional cases.

Chlamydia psittaci infections: a review with emphasis on avian chlamydiosis.

In the first part of this article the general characteristics of Chlamydia psittaci namely the history, taxonomy, morphology, reproductive cycle, metabolism and genetics are reviewed. For the taxonomy in particular, a considerable amount of new information has become available in recent years, following the application of monoclonal antibodies and restriction enzymes. Using these techniques isolates of Chlamydia psittaci from birds have been subdivided in different serovars, a number of isolates have been classified in a new species (Chlamydia pecorum) and isolates from animals have been classified as Chlamydia trachomatis. In the second part of the article, the current knowledge on avian chlamydiosis is summarized. Emphasis is put on clinical signs, lesions, pathogenesis, epizootiology, immunity, diagnosis, prevention and treatment. Also the public health considerations are reviewed. It is concluded that the diagnosis of avian chlamydiosis is laborious and that there is still a need for more accurate, simple and rapid diagnostic tools, both for antigen and antibody detection in various species of birds.

From disease to etiology: historical aspects of Chlamydia-related diseases in animals and humans.

A first description of the etiology of trachoma was published in 1907. During expeditions to Java to study the transmission of syphilis, Halberstaedter and von Prowazek infected orangutans with conjunctival scrapings from trachoma patients and such agents in conjunctival smears. They called them "chlamydozoa". J. Ritter in 1879 published the first case description of psittacosis, describing a mini-epidemic in which three of seven patients died, and identified the source of infection, determined the incubation period and the nontransmissibility of the disease from human to human. In 1895 the term psittacosis was first applied. In 1893, Nocard isolated a Gram-negative bacterium from parrots dying of psittacosis (Bacillus psittacosis). This organism was subsequently found in human or avian subjects and was later diagnosed as Salmonella. The inconsistent bacteriological findings prompted a search for a filterable virus during the pandemic of 1929-1930. Almost simultaneously, Levinthal (1930), Coles (1930) and Lillie (1930) described small, filterable bodies in infectious material called "Levinthal-Coles-Lillie (L.C.L.) bodies". Bedson first suggested the biphasic development cycle in 1932 after having studied tissues from inoculated mice. In 1935, Burnet and Rountree propagated "the virus" on the chorioallantoic membrane of embryonated chicken.

"Contribution to the Question of Pneumotyphus": a discussion of the original article by J. Ritter in 1880.

In 1880, Dr. J. Ritter wrote a classic infectious disease article (originally in German) on psittacosis entitled, "Contribution to the Question of Pneumotyphus." In this article, Ritter meticulously describes a mini-epidemic--in which three individuals died--of seven cases of psittacosis caused by parrots and finches caged in the study of his brother's house in Uster, Switzerland. Ritter accurately identified the study as the site of the source of infection, considered the birds as vectors, and determined both the incubation period and the nontransmissability of the disease from human to human. His main differential diagnosis was a choice between typhoid and typhus; with pneumonitis being the main pathologic finding, he coined the term pneumotyphus. Ritter's article elegantly describes the clinical presentation, epidemiology, pathologic findings, and natural history of infection due to Chlamydia psittaci. Ritter's astute observations and their significance are discussed in this paper.