Zoonotic diseases are infectious diseases which can be transmitted from animals to man. Due to frequent contact and domestication of wildlife animals, zoonotic diseases are increasingly becoming more prevalent. Public parks and gardens are home to abundant populations of birds. One of the most frequent species known to thrive in such areas are feral pigeon (Columba livia). Although there are few reports of disease transmission between pigeons and humans, their close interaction with humans and ability to carry zoonotic pathogens make them a public health risk. In fact, these birds are present at very high densities (2,000 individuals per km2) and can cover a maximum distance of 5.29 km (Dickx et al., 2010). This may result in the increase risk of pathogen transmission among other birds and potentially to humans. Studies have shown that most infected pigeons do not show signs of clinical disease. These birds may therefore pose a public health risk to the human population. Pigeons, like many other bird species, can harbor diseases that can be zoonotic in nature. One of the pathogens most frequently carried by pigeons is Chlamydophila psittaci. C. psittaci is an obligate intracellular bacterium that causes a disease in birds known as Psittacosis or Avian Chlamydiosis. Psittacosis is highly contagious and often causes influenza-like symptoms, severe pneumonia and non-respiratory health problems. Birds can shed this bacterium in the environment when they are either overtly ill or without any symptoms. C. psittaci occurs most frequently in psittacine birds such as parrots, macaws, parakeets. However, non-psittacine birds including pigeons, doves and mynah birds can also harbour the infectious agent (Greco, Corrente, & Martella, 2005). Therefore, pigeons are thought to be an underestimated source of human chlamydiosis.
Studies have shown that pigeons pose a substantial zoonotic risk as are often shown to be naturally infected with a number of viruses, bacteria, fungi and protozoa that are pathogenic to humans. The potential for zoonotic infection is increased as these birds live in close contact with human beings. The aim of this overview is to present the zoonotic potential of C. psittaci in infected feral pigeon populations, in the context of its history, epidemiology and current approaches in treatment and prevention. Pigeon population in urban areas
Commonly known as ‘urban’, ‘street’ or ‘city’ pigeons, the feral rock dove (C. livia) is an abundant bird species that often thrive in streets, squares and parks where they come into close contact with humans. Pigeon populations in most large cities increased worldwide after World War II. They have made contributions of considerable importance to humanity, especially in times of war. Feral pigeons have been domesticated and were put to use by making them messengers due to their homing abilities (Dickx et al., 2010). Pigeons are one of the few animal species able to survive in our noisy and hectic cities. They are extremely adaptable, which also enables them to accept breeding places that are unnatural to them, e.g. on trees or over running ventilation systems (Magnino et al, 2009). They are also a valuable enrichment to the urban environment as they have a cleaning up function by eating discarded food. In addition, they may represent as a tourist attraction as feeding and care of feral pigeons may be rewarding spare-time activities for many people who enjoy the company of animals (Magnino et al, 2009). The extensive food supply and minimal predator population has indeed provided the ecological basis for the large populations that occur in most cities of the world. Chlamydophila psittaci in pigeons
The increase of feral pigeon populations in many cities is a major cause of concern as they are a source of a large number of zoonotic agents. The most important pathogenic organism transmissible from feral pigeons to humans is Chlamydophila...