Outbreaks caused by Chlamydia psittaci and other chlamydial species have recently been reported in poultry farms worldwide, causing considerable economic losses. The objective of this study was to determine the presence of chlamydial species in these birds in Costa Rica. One hundred and fifty pools of lung tissue samples from industrial poultry with respiratory problems and 112 pools of tracheal swabs from asymptomatic backyard poultry were analysed by real-time quantitative polymerase chain reaction (qPCR), end-point PCR and sequencing. A total of 16.8% (44/262) samples were positive for Chlamydia spp., most of them detected in asymptomatic backyard poultry (28.6%, 32/112) and fewer in industrial poultry (8%, 12/150). Of these positive samples, 45.5% (20/44) were determined to be C. psittaci. For the first time C. psittaci genotype A is reported in poultry in Latin America. In addition, the presence of Chlamydia gallinacea in backyard poultry and of Chlamydia muridarum in industrial and backyard poultry is reported for the first time in Central America. In 40.9% (18/44) of the positive samples, it was not possible to identify the infecting chlamydial species. These findings reveal a zoonotic risk, particularly for poultry farm and slaughterhouse workers having direct contact with these birds.

Chlamydia spp. are a group of obligate intracellular pathogens causing a number of diseases in animals and humans. Avian chlamydiosis (AC), caused by Chlamydia psittaci (C. psittaci) as well as new emerging C. avium, C. gallinacea and C. ibidis, have been described in nearly 500 avian species worldwidely. The Crested Ibis (Nipponia nippon) is a world endangered avian species with limited population and vulnerable for various infections. To get a better understanding of the prevalence of Chlamydia spp. in the endangered Crested Ibis, faecal samples were collected and analysed. The results confirmed that 20.20% (20/99) of the faecal samples were positive for Chlamydiaceae and were identified as C. ibidis with co-existence of C. psittaci in one of the 20 positive samples. In addition, ompA sequence of C. psittaci obtained in this study was classified into the provisional genotype Matt116, while that of C. ibidis showed high genetic diversity, sharing only 77% identity with C. ibidis reference strain 10-1398/6. We report for the first time the presence of C. ibidis and C. psittaci in the Crested Ibis, which may indicate a potential threat to the endangered birds and should be aware of the future protection practice.

Psittacosis is a zoonotic infectious disease caused by the transmission of the bacterium Chlamydia psittaci from birds to humans. Infections in humans mainly present as community-acquired pneumonia (CAP). However, most cases of CAP are treated without diagnostic testing, and the importance of C. psittaci infection as a cause of CAP is therefore unclear. In this meta-analysis of published CAP-aetiological studies, we estimate the proportion of CAP caused by C. psittaci infection. The databases MEDLINE and Embase were systematically searched for relevant studies published from 1986 onwards. Only studies that consisted of 100 patients or more were included. In total, 57 studies were selected for the meta-analysis. C. psittaci was the causative pathogen in 1·03% (95% CI 0·79–1·30) of all CAP cases from the included studies combined, with a range between studies from 0 to 6·7%. For burden of disease estimates, it is a reasonable assumption that 1% of incident cases of CAP are caused by psittacosis.

Chlamydia psittaci, depending on its serovar, can infect humans, birds, and other animals and livestock. Its economic impact on poultry production, especially on turkeys and chickens, and potential zoonotic risk have driven the search for an effective vaccination protocol to prevent and control the infection and shedding of the organism. Currently, no vaccine is approved for use against avian chlamydiosis despite efforts in the past decades. The present genomic era presents an opportunity to establish an effective vaccination scheme, taking advantage of the major outer membrane protein (MOMP) as the major protective antigen of C. psittaci. The plasmid DNA expressing MOMP can be coupled with optimisation of controllable factors during vaccination such as codon optimisation (through formation of polyplexes and lipoplexes), route of administration, vaccination schedule, addition of adjuvants/co-stimulatory factors such as cytokines and CpG motifs, and recombination with other poultry pathogens such as viruses. The development of an effective vaccine against C. psittaci will protect susceptible poultry from infection and production performance losses and reduce the zoonotic risk and minimise the emergence of antibiotic-resistant C. psittaci strains.

Zoonotic diseases are a significant health threat for humans and animals. To better understand the epidemiology, etiology, and pathology of infectious agents affecting humans and animals combined approaches are needed. Here we describe an epidemiological investigation conducted by physicians and veterinarians after a reported case of psittacosis. Upon admission suffering from respiratory distress syndrome in a hospital and with a history of bird contact, a female patient was serologically diagnosed with psittacosis. After the case notification, veterinarians were able to investigate the source of infection by detecting Chlamydia psittaci in her pet cockatiel. The bird was hospitalized and successfully treated. In addition, the establishment where the pet bird was purchased was traced and through molecular techniques other birds intended to be sold as pets tested positive for C. psittaci. As a result, sanitary measures were applied and the establishment then was closed down. The birds intended for the pet commerce were treated and retested with negative molecular results for C. psittaci, thus avoiding disease propagation. Reliable data about zoonotic diseases can only be generated through the application of multidisciplinary approaches which take into account the epidemiological factors and interactions of humans, animals and their environments as an integrated system.

In July 2013, a Belgian couple were admitted to hospital because of pneumonia. Medical history revealed contact with birds. Eleven days earlier, they had purchased a lovebird in a pet shop in The Netherlands. The bird became ill, with respiratory symptoms. The couple's daughter who accompanied them to the pet shop, reported similar symptoms, but was travelling abroad. On the suspicion of psittacosis, pharyngeal swabs from the couple were taken and sent to the Belgian reference laboratory for psittacosis. Culture and nested polymerase chain reaction (PCR) tests were positive for the presence of Chlamydia psittaci, and ompA genotyping indicated genotype A in both patients. The patients were treated with doxycycline and the daughter started quinolone therapy; all three recovered promptly. Psittacosis is a notifiable disease in Belgium and therefore local healthcare authorities were informed. They contacted their Dutch colleagues, who visited the pet shop. Seven pooled faecal samples were taken and analysed using PCR by the Dutch national reference laboratory for notifiable animal diseases for the presence of Chlamydia psittaci. Four (57%) samples tested positive, genotyping revealed genotype A. Enquiring about exposure to pet birds is essential when patients present with pneumonia. Reporting to health authorities, even across borders, is warranted to prevent further spread.

A case of sudden sensorineural hearing loss in association with a Chlamydia psittaci pneumonia is reported. Rapid recovery was seen when the patient was treated with high dose steroids and appropriate antibiotics. This is the first such case report in the literature.

Chlamydiosis of domestic poultry (chickens, pheasants, guinea fowl, quail, ducks, geese, and turkeys) is reviewed with emphasis on psittacosis as an occupational disease. The article covers literature from 1940 to 1994. The potential risks of transmission of C. psittaci from poultry to man are discussed, and clinical diseases caused by C. psittaci infection in man are briefly reviewed. Ducks, sometimes without clinical signs, and turkey flocks usually conspicuous for ornithosis during transport or processing, are the most likely sources for poultry transmitted psittacosis. Isolation of the chlamydia, both from man and birds, is the best method for confirmation of the diagnosis. In humans an easier, but less reliable, way is the demonstration of a significant titre rise in properly spaced paired serum samples combined with clinical symptoms. False positive results can occur with the complement fixation test (CFT) commonly used. It has to be remembered that there is a high prevalence of antibodies to different Chlamydia spp. in the population, and that the genus-specific antigen used in the CFT recognizes antibodies to all these pathogens and antibodies resulting from prior infections. More specific serological tests should be favoured, and highly sensitive and specific DNA detection methods, currently mostly used in research, will probably replace tests like the CFT. Case reports of outbreaks of the disease especially among poultry plant workers are compared. With awareness of the problem, employees knowing the clinical signs of psittacosis both in poultry and man, modern abattoir machinery, good sanitary conditions, and early treatment with effective drugs when necessary, the disease risks can be minimized.