Emerging Chlamydia psittaci infections in chickens and
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examination of transmission to humans
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Stefanie Lagae*, Isabelle Kalmar*, Karine Laroucau
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, Fabien Vorimore
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and Daisy
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Vanrompay*
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*Ghent University, Ghent, Belgium;
†
Bacterial Zoonoses Unit of the French Agency for
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Food, Environmental & Occupational Health Safety, Anses, France
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Running title: Chlamydia in chickens and zoonosis
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Corresponding address:
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Ghent University, Faculty of Bioscience Engineering
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Department of Molecular Biotechnology
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Coupure links, 653, 9000 Ghent, Belgium
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Phone: ++32-09-2646065
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Fax: ++32-09-2646219
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E-mail: Stefanie.Lagae@ugent.be
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Abstract
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Chlamydia psittaci and atypical Chlamydiaceae infections are (re)-emerging in chickens. We
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therefore examined the prevalence of C. psittaci, atypical Chlamydiaceae and their zoonotic
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transmission on 19 Belgian chicken farms. Atypical chlamydiaceae were not detected in
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chickens but 18 of 19 and 14 of 19 farms were positive for C. psittaci by both culture and
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PCR, respectively. C. psittaci ompA genotypes A and D were discovered. None of the
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examined humans (n= 31) was infected with atypical Chlamydiaceae, but 29 (93.5%) and 14
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(45%) of them were positive for C. psittaci by both culture and PCR, respectively. Genotypes
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A, D and a mixed infection with genotypes C and D were found. Humans (n = 2) working in
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the C. psittaci negative farm never had respiratory complaints, while 25 of 29 (86.2%)
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positive farmers, reported yearly medical complaints potentially related to psittacosis. Four of
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them currently experienced respiratory disease and one of them was being treated with
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antibiotics. Four farmers (12.5%) mentioned that they had pneumonia after start keeping
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chickens. Occupational physicians should be aware of emerging Chlamydiaceae infections in
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chickens.
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Keywords: Chlamydia psittaci, atypical chicken Chlamydiaceae, zoonosis, psittacosis,
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chickens
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INTRODUCTION
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Chlamydiaceae are gram-negative obligate intracellular bacteria and the species Chlamydia
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psittaci (C. psittaci) causes respiratory disease in birds. C. psittaci infections could be
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demonstrated in at least 465 different bird species, spanning 30 different bird orders (Kaleta
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& Taday, 2003). The symptoms may vary from unapparent to severe, depending on the
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chlamydial strain, stress condition, age and health status of the avian host. The symptoms in
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birds include rhinitis, conjunctivitis, nasal discharge, dyspnoea, diarrhoea, polyuria, anorexia,
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lethargy and dullness (Vanrompay et al., 1995). C. psittaci is a well-known zoonotic agent
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causing psittacosis or parrot-fever in humans. During the last 3 decades, psittacosis outbreaks
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were reported in the US (Grimes & Wyrick, 1991; Newman et al., 1992), China (Ni et al.,
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1996), India (Chahota et al., 2000), Australia (Tiong et al., 2007) and European poultry
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industries (Laroucau et al., 2009; Ryll et al., 1994; Sting et al., 2006; Van Loock et al.,
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2005a; Vanrompay et al., 1997). Zoonotic transfer occurs through inhalation of contaminated
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aerosols originated from feathers, fecal material and respiratory tract exudates. Handling the
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plumage, carcasses and tissues of infected birds and in rare cases, mouth-to-beak contact or
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biting also possess a zoonotic risk (Beeckman & Vanrompay, 2009). Psittacosis in humans
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may vary from unapparent to fatal in untreated patients (Kovacova et al., 2006). Symptoms
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include high fever, chills, headache, myalgia, non-productive coughing and difficult
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breathing (Beeckman & Vanrompay, 2009).
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C. psittaci infections mostly occur on turkey or duck farms. However, C. psittaci infections
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are emerging in European and Asian chickens. Recently, Dickx et al., (2010) examined
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Belgian broiler breeder, broiler and layer farms by a C. psittaci recombinant MOMP-based
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antibody ELISA (Verminnen et al., 2006) and found 98, 95, and 95% seropositive layers,
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broilers, and broiler breeders, respectively. Moreover, they demonstrated C. psittaci genotype
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D in the air of chicken hatching chambers and in slaughtered Belgian and French broilers.
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Zoonotic transmission to hatchery and abattoir employees did occur (Dickx et al., 2010;
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Dickx & Vanrompay, 2011), albeit without severe clinical consequences. Recently, Yin et
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al., (2012), proved Hill's-Evans’ postulates for C. psittaci genotype B and D strains isolated
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from Belgian and French broilers.
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Larouceau et al., (2009) detected a new atypical chlamydial agent in chickens. The atypical
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chicken Chlamydiaceae (ACC) caused apparently no disease in infected chickens, but the
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detection of ACC coincided with 3 cases of atypical pneumonia in individuals working in a
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French poultry abattoir. In 2012, ACC have been detected in Australian, German, Greek,
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Croatian, Slovenian and Chinese chicken flocks (Robertson et al., 2010; Zocevic et al.,
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2012). Importantly, ACC are not detected with C. psittaci-specific molecular tools, rendering
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the need for an ACC-specific PCR. The zoonotic potential and the exact taxonomic status of
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ACC have yet to be defined.
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The aim of the current study was to examine the presence of C. psittaci and ACC on Belgian
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chicken farms, as well as their zoonotic transmission to farmers.
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METHODS
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Study concept
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We investigated the presence of C. psittaci and ACC, as well as their zoonotic transmission,
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on 19 Belgian chicken farms: 7 broiler breeder (1600 to 50,000 animals), 7 broiler (200 to
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150,000 animals) and 5 layer (7000 to 22,000 animals) farms from 4 difference geographical
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regions (Antwerp, East-Flanders, West-Flanders and Limburg). Only 1/19 farms kept
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additional birds species (ducks and geese). The study was conducted in the summer of 2012.
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Participating poultry farms were randomly recruited by phone. A sampling package was
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brought to each poultry farm and sampling was performed immediately. The package
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contained a questionnaire designed to assess information on: 1) the farmers’ professional and
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nonprofessional activities, smoking habits, general health status, use of medication, influenza
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vaccination, allergies, clinical signs potentially related to psittacosis, 2) the chicken breed,
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hatchery, housing, feeding, health status, medication, mortality and 3) the presence of other
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animals on the farm. The package also contained rayon-tipped aluminium shafted swabs
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(Copan, Fiers, Kuurne, Belgium) for pharyngeal sampling of 10 ad random selected chickens
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and the farmers (max 2 per farm). Sampling of the chickens was performed by one of the
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researchers. In the mean time, humans sampled themselves (informed consent) while being in
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their home. Swabs for culture contained 2 ml chlamydia transport medium (Vanrompay et
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al., 1992) while those for PCR contained 2ml DNA stabilization buffer (Roche, Brussels,
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Belgium). Packages were transported on ice and stored at -80°C until use.
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C. psittaci culture
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Culture was performed using Buffalo Green Monkey (BGM) cells, identifying the organism
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by a direct immunofluorescence staining (IMAGEN
TM
, Oxoid, United Kingdom) at 6 days
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post-inoculation. C. psittaci organisms were identified by using the IMAGEN
TM
direct
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