Avian ornithosis, psittacosis or chlamydiosis is an infectious disease that most frequently affects pigeons and psittacines, although it can also affect other species of birds and mammals. In addition, it is an infection that can be transmitted to people, so it is a zoonosis. Its causative agent is Chlamydophila psittaci, an intracellular bacterium that usually causes a persistent infection in infected birds. Most animals remain asymptomatic carriers of the infection, although in cases of immunosuppression, an acute condition may appear that can compromise the life of the animal.
If you are interested in learning more about ornithosis in pigeons, we recommend that you do not miss the following article on our site.
What is ornithosis in pigeons?
Ornithosis, also known as psittacosis or avian chlamydiosis, is an emerging zoonotic disease with worldwide distribution that affects various bird species. Its causal agent was initially named Chlamydia psittaci, but was later reclassified as Chlamydophila psittaci It is of an intracellular bacterium with 8 different serotypes, 6 of which affect birds and can be transmitted to people and other mammals.
Ornithosis is a disease that most frequently affects pigeons and psittacines (such as parrots, parakeets, parakeets and macaws), although up to 150 species of birds have been described as being infected (including poultry, canaries and sea birds). In addition, as we have already mentioned, it is a zoonosis since it can be transmitted to people.
This disease of pigeons usually takes place in an inapparent way. Birds are usually persistently infected, as asymptomatic carriers of the disease. However, in situations of immunocompromise, the bacteria can reactivate their multiplication and give rise to an acute and non-specific condition, characterized by digestive, respiratory and systemic signs.
Transmission of ornithosis in pigeons
Generally, the source of transmission is infected birds as inapparent carriers, which intermittently excrete the bacteria. Transmission of Chlamydophila psittaci can be of two types: vertical or horizontal.
Vertical Transmission
Consists of the transmission of the infection from parents to their children. Typically, nestlings are infected in the nest via food regurgitated by the parents. Surviving offspring may become carriers.
Horizontal transmission
Consists of the transmission of the infection between individuals who do not have a mother-child relationship. In turn, the horizontal transmission can be:
- Direct: by contact with respiratory secretions or feces of infected birds.
- Indirect: due to contact with food, water or contaminated material, especially due to the dust that accumulates in the bottom of the cages from fecal material, feathers, skin flakes, and nasal secretions. Elemental bodies, which are inactive forms of bacteria, can persist for long periods of time in the environment as they are resistant to desiccation.
Symptoms of ornithosis in pigeons
The incubation period (time from exposure to the agent to the appearance of the first symptoms) of ornithosis in pigeons It is very variable. It is usually 3 to 10 days, although it can take months.
The clinical signs of the disease depend on the virulence of the strain, the immune status and the susceptibility of the pigeon. Depending on these factors, the disease can present itself in two different ways: chronic or acute.
Chronic form
Usually, adult and immunocompetent pigeons are chronically infected as asymptomatic carriers, because their etiological agent produces a persistent infection at the level of the nasal glands.
Carrier pigeons shed the bacteria intermittently, being a source of infection for other birds and people.
Acute form
More frequent in pigeons or carrier adults suffering from stress or immunosuppression. Ornithosis in racing pigeons usually occurs in stress situations such as intensive breeding, the competition season or in adverse weather conditions (due to excessive heat or cold).
The acute form presents with nonspecific clinical signs, such as:
- Digestive signs: yellow-green diarrhoea.
- Respiratory signs: eye discharge, conjunctivitis, nasal discharge, sinus swelling, breath sounds, dyspnea (pigeons breathe with their open spout).
- General signs: ruffling of the feathers, weakness, loss of appetite, weight loss and, in the most serious cases, death of the bird.
Diagnosis of ornithosis in pigeons
The diagnosis of ornithosis or psittacosis in pigeons, or other birds, should focus on clinical diagnosis and laboratory diagnosis.
Clinical Diagnosis
The clinical diagnosis of ornithosis is complicated due to the high percentage of infected animals that remain asymptomatic. In acute cases, the clinical diagnosis may be somewhat simpler, although when presenting with non-specific signs it is necessary to consider other respiratory, digestive and/or systemic diseases as differential diagnoses. In this other article we talk about the most common diseases in pigeons.
It is part of the clinical diagnosis:
- Clinical history: the veterinarian will ask about the presence of clinical signs and evolution of the disease.
- General examination of the bird: in order to detect signs associated with the disease, such as serous nasal discharge, infraorbital sinusitis, inflammation of choanae, conjunctivitis, diarrhoea, etc.
- Diagnostic Imaging: X-ray is the most common test. Usually, a loss of the honeycomb pattern of the lung is seen, and sometimes concomitant splenomegaly.
- Hematology and biochemistry: leukocytosis, elevated liver markers and gamma globulinemia may be observed.
Laboratory diagnosis
For laboratory diagnosis, stool samples, cloacal swabs, upper respiratory tract or conjunctiva samples are usually taken It is important to take several samples at over time, since in persistently infected animals the excretion of the bacteria occurs intermittently.
In addition, a series of precautions must be taken when handling the samples to guarantee their conservation. Mishandling of samples can reduce the viability of bacteria and lead to diagnostic errors. For this reason, the samples must be introduced in an adequate buffer and sent quickly to the laboratory to proceed with the diagnosis as soon as possible. As it is a zoonotic agent, the laboratory must be informed of the suspicion and biosafety measures must be followed to avoid transmission to people.
Laboratory diagnosis can be performed using different techniques:
- Direct detection of the aetiological agent: by ELISA, PCR or immunofluorescence.
- Isolation and identification in cell culture: to confirm the diagnosis.
How to treat ornithosis in pigeons?
The treatment of ornithosis in pigeons is based on two fundamental pillars:
- Aetiological treatment: by means of antibacterials. Specifically, the treatment of choice is tetracyclines such as chlortetracycline or doxycycline, although macrolides such as azithromyzine or fluoroquinolones such as enrofloxacin can also be used. For the complete elimination of the infection, long antibiotic treatments are required, above 6 weeks, because chlamydiae are intracellular bacteria.
- Support treatment: a symptomatic treatment will be established depending on the symptoms presented by the animal.
