Brasil
Ciência Rural
Tabla de contenido Anterior Actual Siguiente
Tabla de contenido
MICROBIOLOGY • Cienc. Rural 56 (10) • 2026 • https://doi.org/10.1590/0103-8478cr20240576 linkcopy

Open-access Chlamydia psittaci in free-ranging birds from an Atlantic Forest fragment in Bahia, Brazil

Ocorrência de Chlamydia psittaci em aves de vida livre em área do bioma Mata Atlântica, Bahia, Brasil

ABSTRACT:

Chlamydia psittaci (C. psittaci) is an obligate intracellular bacterium and the etiological agent of chlamydiosis in birds and psittacosis in humans. Despite its zoonotic potential and associated risks to avian biodiversity, the epidemiology of chlamydiosis remains poorly characterized in wild environments and adjacent anthropogenic areas. This study evaluated the occurrence of C. psittaci in the avifauna of the Serra da Jiboia region, an isolated Atlantic Forest fragment in the state of Bahia, Brazil. A total of 111 birds belonging to 55 species were captured, comprising Passeriformes (n = 89), Columbiformes (n = 7), Apodiformes (n = 6), Caprimulgiformes (n = 4), Psittaciformes (n = 3), and Galbuliformes (n=2). Birds were captured using mist nets, and oropharyngeal and cloacal swabs were collected and analyzed by PCR to detect Chlamydia spp., including C. psittaci and C. avium. Six individuals (5.4%; 6/111) tested positive for Chlamydia spp. Of these, two Passeriformes - one Myiophobus fasciatus (Bran-colored Flycatcher, Family Tyrannidae) and one Ceratopipra rubrocapilla (Red-headed Manakin, Family Pipridae) - were positive for C. psittaci, corresponding to 1.8% (2/111) of the sampled population. No individuals tested positive for C. avium. The presence of C. psittaci confirmed its circulation in this wild population and expands current epidemiological knowledge of Chlamydiaceae infections. Further research is needed to clarify interactions between free-ranging and captive birds in surrounding rural areas.

Key words:
Chlamydia sp.; Chlamydia avium ; chlamydiosis; epidemiology; wild birds.

RESUMO:

Chlamydia psittaci (C. psittaci) é uma bactéria intracelular, agente etiológico da clamidiose em aves e psitacose em humanos. Apesar de ser uma zoonose e representar risco à biodiversidade da avifauna, a epidemiologia da clamidiose ainda é pouco estudada no ambiente silvestre e seu entorno antropizado. Deste modo, o objetivo deste estudo foi avaliar a ocorrência de C. psittaci na avifauna da região da Serra da Jiboia, um fragmento isolado de Mata Atlântica, no estado da Bahia, Brasil. Para realizar o objetivo, foram capturadas 111 aves pertencentes a 55 espécies: Passeriformes (n = 89), Columbiformes (n = 7), Apodiformes (n = 6), Caprimulgiformes (n = 4), Psittaciformes (n = 3) e Galbuliformes (n = 2). Após a captura em redes de neblina, amostras de swabs, de orofaringe e cloaca foram coletadas de cada indivíduo e submetidas a análise por meio de PCR para detecção de gênero (Chlamydia sp.) e espécie (C. psittaci e C. avium). Os resultados mostram que seis indivíduos foram detectados positivos para Chlamydia sp. (5,4%; 6/111) e dentre estes dois Passeriformes, um Myiophobus fasciatus (caga-sebo, Família Tyrannidae) e um Ceratopipra rubrocapilla (cabeça-encarnada, Família Pipridae) foram positivos ao nível de espécie para C. psittaci, representando 1,8% (2/111) do total. Nenhum indivíduo foi positivo para C. avium e a presença de C. psittaci nessa população demonstra a circulação do agente em vida livre contribuindo para o conhecimento da epidemiologia das infecções causadas por Chlamydiaceae. No entanto, é necessário pesquisas mais profundas das possíveis interações entre as diferentes espécies de aves de vida livre e as aves cativas residentes nas áreas rurais no entorno da floresta.

Palavras-chave:
Chlamydia sp.; Chlamydia avium ; clamidiose; epidemiologia; aves selvagens.

INTRODUCTION

Chlamydia psittaci (C. psittaci) is the causative agent of chlamydiosis in animals and psittacosis in humans (KNITTLER & SACHSE, 2015; ABDULLAH et al., 2024). It primarily infects birds but occasionally occurs in humans and a wide range of other vertebrates, including mammals, reptiles, amphibians, and fish (SACHSE et al., 2015; BOREL et al., 2018; CASPE & Hill, 2024). Birds in the orders Psittaciformes and Columbiformes are generally considered the most susceptible (HARKINEZHAD et al., 2009; WANG et al., 2024).

Transmission occurs mainly through inhalation of aerosolized respiratory secretions or dried fecal material of infected birds (HARKINEZHAD et al., 2009). In humans, psittacosis ranges from mild influenza-like illness to severe systemic disease with pneumonia. It is typically an occupational zoonosis affecting workers in wildlife rehabilitation centers, veterinary clinics, or breeding facilities (VANROMPAY et al., 1995; GOSBELL et al., 1999), as well as individuals who keep wild birds as pets (RASO et al., 2014; FERREIRA et al., 2015).

Both captive and free-ranging birds act as reservoirs, contributing to environmental persistence of C. psittaci (LEMUS et al., 2010; CASPE & HILL, 2024). Infected birds may be asymptomatic or present with nonspecific clinical signs, such as lethargy, ruffled feathers, blepharitis, conjunctivitis, nasal discharge, dyspnea, diarrhea with yellow-green urates, and death in severe cases (BOREL et al., 2018; BOMMANA & POLKINGHORNE, 2019). Chronically infected birds may shed the pathogen continuously, with clinical disease often triggered by stress (HARKINEZHAD et al., 2009; SACHSE et al., 2009).

Data on C. psittaci in free-ranging birds in Brazil are limited and largely restricted to Psittaciformes (RASO et al., 2006; VAZ et al., 2021) and Columbiformes (LEAL et al., 2015; FERREIRA et al., 2016). Therefore, this study investigated its occurrence in the avifauna of Serra da Jiboia, a preserved Atlantic Forest fragment in the state of Bahia, Brazil, to improve understanding of its regional epidemiology.

MATERIALS AND METHODS

Study area

The study was conducted in the Serra da Jiboia region, in the municipality of Elísio Medrado, Bahia, Brazil. Serra da Jiboia is an isolated Atlantic Forest fragment, covering approximately 440 km² and spanning five municipalities. Bird sampling was conducted at two sites within the study area.

Point 1 (12°52’15.9”S; 39°28’52.6” W) was in dense forest within the Jequitibá Reserve, in the interior of Serra da Jiboia, whereas Point 2 (12°52’18.0”S; 39°29’2.80” W) was situated in an anthropogenic edge habitat adjacent to the Jequitibá Reserve (Figure 1).

thumbnail of Figure 1
Figure 1
Locations of mist net installations and biological sample collection points for captured birds. Point 1: forest interior of the Jequitibá Reserve, Serra da Jiboia; Point 2: forest edge area of Serra da Jiboia, state of Bahia, Brazil.

Mist nets (mesh size: 10 mm; dimensions: 12 x 2 m) were arranged in linear transects. At Point 1, five nets (totaling 60 m) were installed inside the forest, while at Point 2, 20 nets (totaling 240 m) were placed contiguously along the forest edge. Nets remained open from 5 am. to 7 pm. to capture both diurnal and nocturnal species. Sampling was conducted over a single day, with nets inspected every 30 minutes to remove, identify, and sample captured birds.

Sample collection

Birds were identified using a field guide (GRANTSAU, 2010) and classified according to the official Brazilian bird list of the Brazilian Ornithological Records Committee (PACHECO et al., 2021). After identification, birds were banded by a professional licensed by CEMAVE (National Center for Research and Conservation of Wild Birds), in accordance with Brazilian regulations (ICMBio, 2021).Oropharyngeal and cloacal samples were collected using sterile swabs, placed individually in sterile microtubes, and stored at -20 °C until analysis. Birds were released at the capture site immediately after handling.

Molecular analysis

DNA was extracted using the QIAamp® DNA Mini Kit (Qiagen, Germany), according to the manufacturer’s instructions, and stored at -80°C until analysis. Initial PCR screening for Chlamydia spp. targeted a conserved region of the major outer membrane protein (MOMP) gene, as described by EHRICHT et al. (2006), with minor modifications. The primers used were Ch23S-F (5’-CTGAAACCAGTAGCTTATAAGCGGT-3’) and Ch23S-R (5’-ACCTCGCCGTTTAACTTAACTCC-3’), which amplify a 111 bp fragment. Positive samples were subjected to a second PCR protocol for the specific detection of C. psittaci, using the primers CpsiA (5’-ATGAAACATCCAGTCTACTGG-3’) and CpsiB (5’-TTGTGTAGTAATATTATCAAA-3’), as described by LAROUCAU et al. (2001).

Samples positive for Chlamydia spp. were also tested for Chlamydia avium, using the primers ACP-Fw (5’-CATGCAAGCTATTGAGAAAAGTGGT-3’) and ACP-Rv (5’-CCTTGATATGTACGTGTTTTCTCG-3’) amplifying a 108 bp fragment (ZOCEVIC et al., 2013). Negative and positive controls were included in all reactions, using reference strains of C. avium and C. psittaci (Cpsi/Mm/BR01, GenBank accession number JQ926183.1). The PCR products were separated by electrophoresis on 1.5% agarose gels stained with GelRed® (Biotium), visualized under ultraviolet light, and documented.

RESULTS AND DISCUSSION

The Serra da Jiboia is part of the Atlantic Forest biome, recognized as one of the world’s 25 biodiversity hotspots (MYERS, 2000). This mountain range represents a well-preserved, isolated forest fragment with ecological integrity and hydrological importance, serving as a recharge zone for several major regional river basins (RAMOS et al., 2020).

Mist nets were positioned based on site-specific constraints. In dense forest areas (Point 1), thick understory vegetation restricted net deployment, whereas the forest edge (Point 2) provided more open space, allowing more nets to be installed. In total, 111 free-ranging birds representing 55 species across six orders were captured. The taxonomic composition, sample sizes, and Chlamydiaceae screening results for each species are presented in table 1.

Thumbnail
Table 1
Detection of Chlamydia spp. and Chlamydia psittaci in birds captured at Serra da Jiboia, Bahia, Brazil.

Body mass ranged from 2 g (Amazilia nigricauda, Glaucis hirsutus) to 126 g (Leptotila verreauxi). Most individuals were adults (91%; 101/111), with juveniles comprising 7.2% (8/111) and individuals of undetermined age 1.8% (2/111). Sex could not be determined for most birds (59%; 65/111), while 26% (29/111) were males and 15% (17/111) were females.

Notably, most species (54/55) are classified as “Least Concern” (LC) by the IUCN (International Union for Conservation of Nature). The only exception was Myrmotherula urosticta (family Thamnophilidae, order Passeriformes), categorized as “Vulnerable” (VU), primarily due to habitat loss and degradation (BIRDLIFE INTERNATIONAL, 2023), consistent with its restricted distribution in the central Atlantic Forest corridor.

Passeriformes accounted for 80% (44/55) of the species and 80.2% (89/111) of the sampled individuals. Although the number of individuals per species was low, the sample was relatively evenly distributed, reflecting the high biodiversity of the study area. This pattern indicates sufficient ecological complexity to sustain diverse ecological niches. However, birds inhabiting forest edges are exposed to intense anthropogenic pressure from small-scale agriculture surrounding Serra da Jiboia (CARVALHO-SOBRINHO et al., 2005). Close contact between wild birds and domestic or subsistence poultry may facilitate transmission cycles of Chlamydia species, posing a potential risk to regional avifauna.

The overall prevalence of Chlamydia spp. infection was 5.4% (6/111), with C. Psittaci detected in two individuals (1.8%; 2/111) (Table 1). No birds showed clinical signs consistent with chlamydiosis. All samples positive for Chlamydia spp. tested negative for Chlamydia avium. Although the pathogenicity and zoonotic potential of C. avium remain unclear, infections have been reported in Psittaciformes and Columbiformes (ZOCEVIC et al., 2013).

One C. psittaci-positive individual, Ceratopipra rubrocapilla (Pipridae; Red-headed Manakin), was captured in a forest interior habitat (Point 1). The second, Myiophobus fasciatus (Tyrannidae; Bran-colored Flycatcher), was captured at the forest edge (Point 2) and is typically associated with anthropogenic or open habitats (OLIVEIRA, 2012). To our knowledge, this is the first report of C. psittaci infection in both wild species. The remaining Chlamydia spp.-positive individuals (genus-level identification) were captured at Point 2 and included Galbula ruficauda, Camptostoma obsoletum, Furnarius leucopus, and Loriotus cristatus. These species occur across multiple Brazilian biomes, including the Atlantic Forest, Cerrado, and Caatinga (MOREIRA-LIMA, 2013).

The family Chlamydiaceae comprises a single genus, Chlamydia, currently encompassing 11 recognized species (BOREL et al., 2018), including C. psittaci and C. avium, which were the focus of this study. Birds occupying multiple habitats may increase the risk of Chlamydia spp. transmission and dissemination, either through occasional contact with subsistence, domestic, or commercial poultry, or via interactions across diverse natural environments. However, the limited number of individuals per species prevented statistical comparisons between collection sites (forest and anthropogenic areas).

In Brazil, a study conducted in a forest reserve in Paraíba state assessed C. psittaci in free-ranging birds from Cerrado and semideciduous forest habitats (LUGARINI et al., 2021). Among 123 sampled birds C. psittaci was detected in 1.6% of individuals, with similar frequencies in the Cerrado (1.5%; 1/65) and semideciduous forest habitats (1.7%; 1/58). The two positive birds were Leptotila rufaxilla (Family Columbidae, Order Columbiformes) and Tapera naevia (Family Cuculidae, Order Cuculiformes) (LUGARINI et al., 2021). Although these species were not sampled in the present study, the C. psittaci detection rates were comparable. Notably, despite a larger sample of Passeriformes, no C. psittaci was detected in this order in this study.

Nocturnal sampling yielded four Nyctidromus albicollis individuals (Pauraque, Family Caprimulgidae), for which no previous records of Chlamydia spp. infection are available. Conversely, Psittaciformes (3/111) and Columbiformes (7/111) sampled here were negative for C. psittaci, despite these groups being commonly associated with infection (BOREL et al., 2018; WANG et al., 2024).

The reported prevalence of Chlamydia spp. in free-ranging Passeriformes varies internationally. In Switzerland, Chlamydiaceae prevalence was 0.4%, although species-level identification was not achieved (ZWEIFEL et al., 2009). Studies in Sweden and the United Kingdom detected C. psittaci in 2-2.9% of birds sampled in public parks, particularly in Paridae species (OLSEN et al., 1998; BECKMANN et al., 2014; SPORNDLY-NEES et al., 2023). However, the species identified as positive in those studies differ from those reported in Brazil.

Although C. psittaci is rarely detected in Passeriformes, habitat alteration may increase physiological stress in wild populations, potentially reducing immune competence and increasing susceptibility to infection (HARKINEZHAD et al., 2009; KRAWIEC et al., 2015; BURNARD & POLKINGHORNE, 2016).

CONCLUSION

The detection of C. psittaci in this population of wild birds confirmed its circulation among free-ranging Passeriformes and contributes to the epidemiological characterization of this pathogen. Further studies are needed to identify additional Chlamydia species and evaluate their epidemiological relevance. Improved understanding of interactions between wild birds and domestic poultry in surrounding rural areas is also needed. Precise identification of primary infection sources, particularly in transition zones between agricultural and preserved forest environments, is essential for assessing health risks to avian populations facing ongoing habitat loss.

ACKNOWLEDGMENTS

This study was financed in party by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.

REFERENCES

CR-2024-0576.R1

DATA AVAILABILITY STATEMENT

The data can be obtained from the author upon request.

BIOETHICS AND BIOSECURITY COMMITTEE APPROVAL

The study was conducted under license from the Sistema de Autorização e Informação em Biodiversidade (SISBIO) of the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio) (protocol No. 63652-1) and was approved by the Comissão de Ética no Uso de Animais (CEUA) of the Escola de Medicina Veterinária e Zootecnia, Universidade Federal da Bahia (UFBA) (EMEVZ-UFBA) (protocol No. 60/2018).

DECLARATION OF USE OF ARTIFICIAL INTELLIGENCE

No artificial intelligence tools were used in the preparation of this article.

Correspondence

E-mail: frankeufba@gmail.com. *Corresponding author

ASSOCIATE EDITOR:

Rudi Weiblen (0000-0002-1737-9817)

SCIENTIFIC EDITOR:

Juliana Felipetto Cargnelutti (0000-0002-3160-3643)

DECLARATION OF CONFLICT OF INTEREST

The authors have no conflicts of interest to declare.

AUTHORS’ CONTRIBUTIONS

All authors contributed equally to the study conception and manuscript preparation, critically reviewed the content and approved the final version.

Publication Dates

  • Publication in this collection
    14 Sept 2026
  • Date of issue
    2026

History

  • Received
    11 Jan 2024
  • Accepted
    08 May 2026
  • Reviewed
    29 June 2026
Creative Common - by 4.0
This is an open-access article distributed under the terms of the Creative Commons Attribution License
location_on
Universidade Federal de Santa Maria Universidade Federal de Santa Maria, Centro de Ciências Rurais , 97105-900 Santa Maria RS Brazil , Tel.: +55 55 3220-8698 , Fax: +55 55 3220-8695 - Santa Maria - RS - Brazil
E-mail: cienciarural@mail.ufsm.br
rss_feed Acompañe los números de esta revista en su lector de RSS
Notificar error