Risk assessment and management of Chlamydia psittaci in poultry processing plants

Chlamydia psittaci seropositivity in workers exposed to birds and review of the literature: Evidence of circulation in Antioquia

Introduction

Psittacosis is a zoonotic disease caused by Chlamydia psittaci, a bacterium classified as an agent with bioterrorist potential. It has caused multiple outbreaks in exposed poultry workers around the world. Colombia has no epidemiological follow-up of the infection and a big knowledge gap.

Objectives

To determine the antibodies’ frequency against C. psittaci in workers with occupational exposure to birds and to review the literature on studies conducted in Colombia.

Materials and methods

We conducted a cross-sectional descriptive study with analytical intent on workers in contact with birds and reviewed the related literature in Colombia. IgM and IgG serum antibodies against C. psittaci were detected by microimmunofluorescence. The sociodemographic and exposure characteristics were expressed as frequencies and summary measures. Associated factors were explored by bivariate and multivariate analysis. The scientific and gray literature review was done with a structured search.

Results

We analyzed 54 workers in contact with birds. Antibody prevalence was 31.5%. Slaughtering and evisceration by non-veterinarians was a risk factor for antibody presence. There are only four previous studies on C. psittaci in Colombia.

Conclusions

Here, we present the first evidence of C. psittaci circulation among workers exposed to birds in Antioquia and the second report in the country. These findings contribute to the “One Health” public health strategy.

Undiagnosed Cases of Human Pneumonia Following Exposure to Chlamydia psittaci from an Infected Rosella Parrot

This report describes two cases of occupational exposure to Chlamydia psittaci following dissection of an infected Rosella (Platycercus elegans). The C. psittaci infections (with one of them resulting in diagnosed pneumonia and hospitalisation) were undiagnosed during routine medical investigations but later established due to epidemiological and clinical evidence, and molecular testing of the archived Rosella’ specimens. This case report stresses the importance of correct application and interpretation of diagnostic tests and the need to raise awareness about this zoonotic pathogen among medical practitioners and people exposed to potential animal carriers. Our findings suggest other infected individuals might be misdiagnosed and that C. psittaci (psittacosis) is likely to be underreported in Australia. This case highlights the need to operationalise the One Health concept. We call for improved communication between human and animal health service providers to allow accurate and rapid diagnosis of this zoonotic disease and raised awareness among medical practitioners. Further targeted surveys of wild birds (and other animals) should be conducted to improve assessment of risks to the general population and people working with or exposed to wild birds.

Animal sources for zoonotic transmission of psittacosis: a systematic review

Background

Human psittacosis, caused by Chlamydia (C.) psittaci, is likely underdiagnosed and underreported, since tests for C. psittaci are often not included in routine microbiological diagnostics. Source tracing traditionally focuses on psittacine pet birds, but recently other animal species have been gaining more attention as possible sources for human psittacosis. This review aims to provide an overview of all suspected animal sources of human psittacosis cases reported in the international literature. In addition, for each animal species the strength of evidence for zoonotic transmission was estimated.

Methods

A systematic literature search was conducted using four databases (Pubmed, Embase, Scopus and Proquest). Articles were included when there was mention of at least one human case of psittacosis and a possible animal source. Investigators independently extracted data from the included articles and estimated strength of evidence for zoonotic transmission, based on a self-developed scoring system taking into account number of human cases, epidemiological evidence and laboratory test results in human, animals, and the environment.

Results

Eighty articles were included, which provided information on 136 different situations of possible zoonotic transmission. The maximum score for zoonotic transmission was highest for turkeys, followed by ducks, owls, and the category ‘other poultry’. Articles reporting about zoonotic transmission from unspecified birds, psittaciformes and columbiformes provided a relatively low strength of evidence. A genotypical match between human and animal samples was reported twenty-eight times, including transmission from chickens, turkeys, guinea fowl, peafowl, pigeons, ducks, geese, songbirds, parrot-like birds and owls.

Conclusions

Strong evidence exists for zoonotic transmission from turkeys, chickens and ducks, in addition to the more traditionally reported parrot-like animal sources. Based on our scoring system, the evidence was generally stronger for poultry than for parrot-like birds. Psittaciformes should not be disregarded as an important source of human psittacosis, still clinicians and public health officials should include poultry and birds species other than parrots in medical history and source tracing.

Review of Nonfoodborne Zoonotic and Potentially Zoonotic Poultry Diseases

Emerging and re-emerging diseases are continuously diagnosed in poultry species. A few of these diseases are known to cross the species barrier, thus posing a public health risk and an economic burden. We identified and synthesized global evidence for poultry nonfoodborne zoonoses to better understand these diseases in people who were exposed to different poultry-related characteristics (e.g., occupational or nonoccupational, operational types, poultry species, outbreak conditions, health status of flocks). This review builds on current knowledge on poultry zoonoses/potentially zoonotic agents transmitted via the nonfoodborne route. It also identifies research gaps and potential intervention points within the poultry industry to reduce zoonotic transmission by using various knowledge synthesis tools such as systematic review (SR) and qualitative (descriptive) and quantitative synthesis methods (i.e., meta-analysis). Overall, 1663 abstracts were screened and 156 relevant articles were selected for further review. Full articles (in English) were retrieved and critically appraised using routine SR methods. In total, eight known zoonotic diseases were reviewed: avian influenza (AI) virus (n = 85 articles), Newcastle disease virus (n = 8), West Nile virus (WNV, n = 2), avian Chlamydia (n = 24), Erysipelothrix rhusiopathiae (n = 3), methicillin-resistant Staphylococcus aureus (MRSA, n = 15), Ornithonyssus sylvarium (n = 4), and Microsporum gallinae (n = 3). In addition, articles on other viral poultry pathogens (n = 5) and poultry respiratory allergens derived from mites and fungi (n = 7) were reviewed. The level of investigations (e.g., exposure history, risk factor, clinical disease in epidemiologically linked poultry, molecular studies) to establish zoonotic linkages varied across disease agents and across studies. Based on the multiple outcome measures captured in this review, AI virus seems to be the poultry zoonotic pathogen that may have considerable and significant public health consequences; however, epidemiologic reports have only documented severe human cases clustered in Asia and not in North America. In contrast, avian Chlamydia and MRSA reports clustered mainly in Europe and less so in North America and other regions. Knowledge gaps in other zoonoses or other agents were identified, including potential direct (i.e., nonmosquito-borne) transmission of WNV from flocks to poultry workers, the public health and clinical significance of poultry-derived (livestock-associated) MRSA, the zoonotic significance of other viruses, and the role of poultry allergens in the pathophysiology of respiratory diseases of poultry workers. Across all pathogens reviewed, the use of personal protective equipment was commonly cited as the most important preventive measure to reduce the zoonotic spread of these diseases and the use of biosecurity measures to reduce horizontal transmission in flock populations. The studies also emphasized the need for flock monitoring and an integrated approach to prevention (i.e., veterinary-public health coordination with regard to diagnosis, and knowledge translation and education in the general population) to reduce zoonotic transmission.

Temporal and spatial analysis of psittacosis in association with poultry farming in the Netherlands, 2000-2015

Background

Human psittacosis is a highly under diagnosed zoonotic disease, commonly linked to psittacine birds. Psittacosis in birds, also known as avian chlamydiosis, is endemic in poultry, but the risk for people living close to poultry farms is unknown. Therefore, our study aimed to explore the temporal and spatial patterns of human psittacosis infections and identify possible associations with poultry farming in the Netherlands.

Methods

We analysed data on 700 human cases of psittacosis notified between 01-01-2000 and 01-09-2015. First, we studied the temporal behaviour of psittacosis notifications by applying wavelet analysis. Then, to identify possible spatial patterns, we applied spatial cluster analysis. Finally, we investigated the possible spatial association between psittacosis notifications and data on the Dutch poultry sector at municipality level using a multivariable model.

Results

We found a large spatial cluster that covered a highly poultry-dense area but additional clusters were found in areas that had a low poultry density. There were marked geographical differences in the awareness of psittacosis and the amount and the type of laboratory diagnostics used for psittacosis, making it difficult to draw conclusions about the correlation between the large cluster and poultry density. The multivariable model showed that the presence of chicken processing plants and slaughter duck farms in a municipality was associated with a higher rate of human psittacosis notifications. The significance of the associations was influenced by the inclusion or exclusion of farm density in the model.

Conclusions

Our temporal and spatial analyses showed weak associations between poultry-related variables and psittacosis notifications. Because of the low number of psittacosis notifications available for analysis, the power of our analysis was relative low. Because of the exploratory nature of this research, the associations found cannot be interpreted as evidence for airborne transmission of psittacosis from poultry to the general population. Further research is needed to determine the prevalence of C. psittaci in Dutch poultry. Also, efforts to promote PCR-based testing for C. psittaci and genotyping for source tracing are important to reduce the diagnostic deficit, and to provide better estimates of the human psittacosis burden, and the possible role of poultry.

Assessment of Chlamydia psittaci Shedding and Environmental Contamination as Potential Sources of Worker Exposure throughout the Mule Duck Breeding Process

Chlamydia psittaci is an obligate intracellular bacterium responsible for avian chlamydiosis, otherwise known as psittacosis, a zoonotic disease that may lead to severe atypical pneumonia. This study was conducted on seven mule duck flocks harboring asymptomatic birds to explore the circulation and persistence of C. psittaci during the entire breeding process and assess the potential sources of worker exposure. Cloacal swabs and air samples were taken on each occasion requiring humans to handle the birds. In parallel, environmental samples, including dust, water, and soil, were collected. Specific real-time PCR analyses revealed the presence of C. psittaci in all flocks but with three different shedding patterns involving ducks about the age of 4, 8, and 12 weeks with heavy, moderate, and low excretion levels, respectively. Air samples were only positive in flocks harboring heavy shedders. Dust in flocks with heavy or moderate shedders carried chlamydial loads strongly associated with the loads detected in avian and soil samples. Environmental contamination, significantly correlated with shedding dynamics, was considered to be the most probable source of exposure. The high prevalence of bacteriophage Chp1 in all flocks, mostly jointly present with chlamydia, suggests an important factor in C. psittaci persistence, thus creating a greater risk for humans. A survey conducted in these flocks regarding farming practices and activities showed that disinfection seems to be the most promising practice for reducing C. psittaci prevalence in ducks and that the place and the duration of action during operations seem to be potential risk factors. Strict adherence to good practices is strongly recommended.

An Unusual Outbreak of Chlamydiosis in Commercial Turkeys Involving the Nasal Glands

An unusual outbreak of chlamydiosis was diagnosed in 15,000, 13-wk-old organically grown turkeys housed in a semiconfinement housing system. The disease was characterized by unilateral or bilateral swelling above the eye due to mild-to-severe inflammation of the nasal glands in 3%-5% of the birds. Except for a slight drop in feed and water consumption, the birds did not exhibit any respiratory signs, morbidity, and mortality. Chlamydiosis in the turkeys was confirmed by immunofluorescence, immunohistochemistry, and PCR assay of the nasal glands. Other samples such as conjunctiva, lungs, air sacs, heart, liver, spleen, and feces were negative for chlamydia by florescence antibody test in birds submitted over several weeks. Chlamydia psittaci strain B was isolated in chicken egg embryos and typed by multilocus sequence variable number of tandem repeats analysis, multilocus sequence typing, and ompA gene sequencing as a CP3-like strain. This is the first report of a naturally occurring chlamydiosis affecting the nasal glands in turkeys.

Emerging Chlamydia psittaci infections in chickens and examination of transmission to humans

Chlamydia psittaci and atypical Chlamydiaceae infections are (re)-emerging in chickens. We therefore examined the prevalence of C. psittaci, atypical Chlamydiaceae and their zoonotic transmission on 19 Belgian chicken farms. Atypical Chlamydiaceae were not detected in chickens but 18 out of 19 farms were positive for C. psittaci by culture and PCR. C. psittaci ompA genotypes A and D were discovered. None of the examined humans (n = 31) was infected with atypical Chlamydiaceae, but 29 (93.5%) of them were positive for C. psittaci by culture and PCR. Genotypes A, D and a mixed infection with genotypes C and D were found. Humans (n = 2) working at the C. psittaci-negative farm never had respiratory complaints, while 25 out of 29 positive farmers (86.2%) reported yearly medical complaints potentially related to psittacosis. Four of them currently experienced respiratory disease and one of them was being treated with antibiotics. Four farmers (12.5%) mentioned that they had pneumonia after starting to keep chickens. Occupational physicians should be aware of emerging Chlamydiaceae infections in chickens.

Comparative analysis of Chlamydia psittaci genomes reveals the recent emergence of a pathogenic lineage with a broad host range

Chlamydia psittaci is an obligate intracellular bacterium. Interest in Chlamydia stems from its high degree of virulence as an intestinal and pulmonary pathogen across a broad range of animals, including humans. C. psittaci human pulmonary infections, referred to as psittacosis, can be life-threatening, which is why the organism was developed as a bioweapon in the 20th century and is listed as a CDC biothreat agent. One remarkable recent result from comparative genomics is the finding of frequent homologous recombination across the genome of the sexually transmitted and trachoma pathogen Chlamydia trachomatis. We sought to determine if similar evolutionary dynamics occurred in C. psittaci. We analyzed 20 C. psittaci genomes from diverse strains representing the nine known serotypes of the organism as well as infections in a range of birds and mammals, including humans. Genome annotation revealed a core genome in all strains of 911 genes. Our analyses showed that C. psittaci has a history of frequently switching hosts and undergoing recombination more often than C. trachomatis. Evolutionary history reconstructions showed genome-wide homologous recombination and evidence of whole-plasmid exchange. Tracking the origins of recombinant segments revealed that some strains have imported DNA from as-yet-unsampled or -unsequenced C. psittaci lineages or other Chlamydiaceae species. Three ancestral populations of C. psittaci were predicted, explaining the current population structure. Molecular clock analysis found that certain strains are part of a clonal epidemic expansion likely introduced into North America by South American bird traders, suggesting that psittacosis is a recently emerged disease originating in New World parrots.

Chlamydia psittaci is classified as a CDC biothreat agent based on its association with life-threatening lung disease, termed psittacosis, in humans. Because of the recent remarkable findings of frequent recombination across the genome of the human sexually transmitted and ocular trachoma pathogen Chlamydia trachomatis, we sought to determine if similar evolutionary dynamics occur in C. psittaci. Twenty C. psittaci genomes were analyzed from diverse strains that may play a pathogenic role in human disease. Evolution of the strains revealed genome-wide recombination occurring at a higher rate than for C. trachomatis. Certain strains were discovered to be part of a recent epidemic clonal expansion originating in South America. These strains may have been introduced into the United States from South American bird traders, suggesting that psittacosis is a recently emerged disease originating in New World parrots. Our analyses indicate that C. psittaci strains have a history of frequently switching hosts and undergoing recombination.

A real-time PCR assay for the detection of atypical strains of Chlamydiaceae from pigeons

Recent evidence of the occurrence of atypical Chlamydiaceae strains in pigeons, different from the established Chlamydiaceae, requires the development of a specific and rapid detection tool to investigate their prevalence and significance. Here is described a new real-time PCR assay that allows specific detection of atypical Chlamydiaceae from pigeons. The assay has been used to assess the dissemination of these strains in field samples collected from Parisian pigeon populations in 2009. The results suggest a limited dissemination compared to the usually higher prevalence of Chlamydia psittaci that is the main species associated with avian chlamydiosis.