Chlamydial infections in feral pigeons in Europe: Review of data and focus on public health implications

• Published in: Veterinary microbiology 2009-03, Vol.135 (1), p.54-67
• Main Authors: Magnino, S., Haag-Wackernagel, D., Geigenfeind, I., Helmecke, S., Dovč, A., Prukner-Radovčić, E., Residbegović, E., Ilieski, V., Laroucau, K., Donati, M., Martinov, S., Kaleta, E.F.
• Format: Article
• Language: English
• Subjects: Animals; Animals, Wild; antibody detection; antigen detection; Bird Diseases - epidemiology; Bird Diseases - microbiology; Chlamydia Infections - epidemiology; Chlamydia Infections - veterinary; Chlamydophila psittaci; Columba livia; Columbidae; data analysis; Diagnosis; disease transmission; epidemiological studies; Epidemiology; Europe - epidemiology; feral animals; Feral pigeons; Health hazard; literature reviews; pigeons; psittacosis; Public Health; seroprevalence; zoonoses; Zoonosis
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/j.vetmic.2008.09.045

Feral pigeons ( Columba livia domestica), which thrive in most European towns and cities, are commonly infected with the zoonotic bacterium Chlamydophila psittaci, the agent of psittacosis (also known as ornithosis) in humans. A number of surveys carried out over the last thirty years across Europe have detected high seropositivity values and high percentages of infection in feral pigeon populations. Overall, when considering data from 11 European countries, seropositivity values to C. psittaci in the sampled populations ranged from 19.4% to 95.6%. In most surveys, the complement fixation test was used, and antibodies were detected in 19.4–66.3% of the samples, with a median of 46.1%. Indirect immunofluorescence and ELISA tests were employed less frequently, but led to the detection of higher percentages of seropositivity (23.7–67.7% and 35.9–95.6%, respectively). Attempts to grow C. psittaci in cell culture or embryonated chicken eggs were successful in 2–42.3% and 0–57.1% of samples, respectively, antigen detection methods were positive in 2.3–40% of samples, while conventional PCR and real-time PCR using different genomic targets detected the organism in 3.4–50% of samples. Twenty-five C. psittaci isolates from pigeons were typed as ompA genotype B ( n = 14), E ( n = 10) and E/B ( n = 1). The huge increase of feral pigeon populations in Europe is a major cause of concern for the detrimental effect of pigeon droppings on environmental hygiene, in addition to the extensive damage due to the fouling of buildings and monuments. The most important pathogenic organism transmissible from feral pigeons to humans is C. psittaci, with 101 cases of disease reported in the literature. Exposure to C. psittaci-contaminated dust, direct contact with pigeons through handling and, to a lesser extent, through pigeon feeding have been identified as hazardous exposures in more than half of the human cases, while loose or transient contacts with feral pigeons have been mentioned in about 40% of the cases. Education initiatives as to the communication of a health risk resulting from contact with pigeons and pigeon excreta should primarily be targeted at individuals who may be exposed to C. psittaci-contaminated dust, such as demolition/construction workers. Recommendations to this category of workers include wearing protective clothes with hoods, boots, gloves and air filter face masks when removing pigeon faeces from roofs, garrets and buildings, especially if working indoo