Want to Know About Psittacosis? Learn It Here

Chlamydia, also known as psittacosis or chlamydial infection, is a disease caused by a bacterium, called by its scientific name as Chlamydiophila psittaci. This condition affects birds, especially parakeets, parrots and pigeons. But it is also a serious zoonosis because the disease is in fact transmissible to humans.

What is it?

Chlamydiophila psittaci affects birds, mainly parrots, parakeets and pigeons. It can be transmitted to cats but also to humans. In humans, it causes a severe flu syndrome, which does not pass without proper antibiotic treatment. This is partly why this disease must be detected early and taken seriously.


They are diverse because bacteria can attack different devices:

  • Respiratory : nasal discharge (clear or purulent), shortness of breath.
  • Ocular : conjunctivitis (red eye, watery eyes) and keratitis (inflammation of the cornea).
  • Digestive: diarrhea, with more or less liquid yellow-greenish feces.
  • Urinary: polyuria (increased urinary volume) and greenish coloration of the urine.
  • General: depressed plumage, anorexic, bristling, weight loss, sudden death.


Diagnosis is not easy because the symptoms are varied and not very specific.

  • A swab of the eye and cloaca allows a serological test to find the bacteria. A blood test makes it possible to look for the bacteria by PCR.

However, these tests are difficult and, if negative, do not provide absolute certainty that this is not chlamydia.

  • The blood test also revealed leukocytosis (increased number of white blood cells) and an increase in certain biochemical parameters (proteins, AST, globulins, total bile acids).

Radiography may also be performed to assess the degree of respiratory system involvement.

  • In dead animals, an autopsy can be performed and histological analysis of the liver, kidneys and spleen can help in the diagnosis. (See Article: Flagship Macaw)


The treatment of Psittacosis is very long, 4 to 6 weeks minimum and depends on the use of specific antibiotics. Note that some animals may heal, but can potentially carry the bacteria.

Parrot psittacosis treatment and its effectiveness and prognosis may vary depending on the bird’s general health, age and the presence of secondary infections. It will still be necessary to isolate the animal and administer antibiotics for a minimum period of 45 days; routes of administration may be as follows:

  • Oral administration
  • Administration by injection
  • Administration by meal

At the end of the treatment period, the veterinarian may suggest one more laboratory test to check the efficacy of the treatment and may also recommend medication for the birds that had contact with the infected parrot.

How to avoid the disease in parrots?

The best way is prevention. It is advisable to test for this bacterium when buying a parrot or as part of a breeding to detect carrier birds. Environmental hygiene is very important to limit contamination. It is also advisable to minimize stress and provide a quality diet to avoid any immune weakness. Avoid contact with sick or suspect birds, especially in newly purchased birds that have been under stress.

Psittacosis In Humans

Transmission of psittacosis from a bird to a person is rare and not very serious, as the person has symptoms similar to those of a flu or cold. However, the consequences can be fatal for children, pregnant women, the elderly and immunocompromised persons.

To prevent your parrot from suffering from psittacosis and transmitting it to others, it can be very useful to follow these tips:

  • The cage must be in optimal hygienic conditions
  • Do not stay in an enclosed area where birds live
  • Do not adopt birds without their corresponding health certificate.If your parrot is suffering from psittacosis, it is important to take hygienic measures, wear gloves and wash hands after handling.
  • The transmission of psittacosis to birds and humans can be avoided with simple hygienic measures, so it is important to take into account the recommendations described above.


Transmission (bird-to-human) is mainly airborne by inhalation of contaminated aerosols. The materials with the highest bacterial load are bird droppings and oculo-nasal secretions. Plumage, urine and blood may also be contaminated.

Human contamination is favored by close contact with carrier birds that are themselves sick or not (direct contact with the bird, handling, care, cleaning of cages), but short-term exposure may be sufficient to cause infection. However, in approximately 30% of cases, no notion of contact with the birds is found.

Person-to-person transmission is possible but very rare.

  • Incubation: Incubation takes an average of 5 to 15 days. In some cases described, it may take up to one month<br

Neurological and hepatic complications, vascular (DIC) and renal diseases are also observed. Case fatality is 10-20% without treatment, but less than 1% with antibiotic therapy.


  • Look for contact with domestic or wild birds or bird droppings
  • In case of identification of suspected sources: biological tests as well as isolation and treatment of sick birds with cleaning and disinfection of the cage or aviary (with adequate protection). In some cases, infected birds that do not respond to treatment should be culled.


  • Look for other cases of psittacosis in the same region
  • Active search for anyone who may have been in contact with sick birds or passed through the facility after the birds have passed through (even for short periods of time, as there are outbreaks among visitors to bird shows that have been described).
  • Inform exposed persons and the attending physician about the signs of the disease and the symptoms of the disease.
  • Hygiene measures to be applied at all times.

Importance in public health

Psittacosis is a bacterial zoonosis caused by Chlamydia psittaci. The disease is also called ornithosis or parrot fever (avian chlamydia) due to its transmission by birds (mainly of the parrot family).IgA titer in combination with a doubling of the IgG titer determined by FC, MIF or Elisa.

Possible Case

  • Any person meeting the clinical criteria is considered to be in contact with an infected bird, or with an epidemiological link to a confirmed case.

Probable Case

  • Any person meeting the following clinical and laboratory criteria: IgM titer against C. psittaci greater than or equal to 16 (or the titer indicated by the assay manufacturer) in a serum obtained after symptom onset.

Confirmed case

  • Any person who meets the clinical criteria and at least one of the laboratory criteria.


  • Age group: No specific age.
  • Incidence of impact: Less than 15 cases reported annually by the laboratory surveillance network. Most of the time the disease is most likely undiagnosed and unreported.
  • Immunity: No documented immunity. Possible reinfections because there are several serovars.
  • Geography: Sex ratio is widespread throughout the world.

Populations at Risk

  • Groups at risk for developing the disease: Anyone who comes into contact with birds at work or in their leisure time. Several epidemics have been reported in humans following bird exposures.
  • Groups at risk of developing severe forms: The immunocompromised.

Psittacosis In Pregnancy


  • Higher mortality among pregnant women. Reported complications are: severe atypical pneumonia, hepatitis, premature birth, renal failure, fetal death in utero.

Patient management

  • First choice: Doxycycline PO 200 mgThe microimmunofluorescence technique is more sensitive and specific, but cross-reactions may also occur.

Consequently, positive serologies may be the result for other chlamydiaceae species and should be interpreted with caution. To increase the reliability of the results, tests should be repeated by the same laboratory on sera collected in the acute and convalescent phase at least two weeks before the interval procedure.

It should also be noted that antibiotic treatment may inhibit antibody development and alter serological results (false negative). PCR diagnosis has been validated for avian samples and is used for human diagnosis of sputum or bronchoalveolar fluid in the reference laboratory.

Given the lack of specificity of currently available diagnostic methods and the time required to confirm an infection, treatment of psittacosis should be initiated on the basis of clinical suspicion and anamnesis, as well as a first serum for serological follow-up, should be as soon as possible.

General Preventive Measures

Individual and collective preventive measures are recommended, especially in areas of higher risk (poultry farming, hatcheries, slaughterhouses, etc.). It is important to be careful as birds can excrete the bacteria. Information on psittacosis and recommendations for good husbandry practices for professional and non-professional poultry breeders

  • Hygiene measures for humans. Personal hygiene measures: wash hands after any contact with the product.
  • Birds. Optimization of general ventilation and dust collection
  • Regular disinfection of cages
  • Wear appropriate work clothes and personal protection during work.
  • Cleaning of cages and aviaries
  • Humidification of bird droppings before washing (to avoid dust and aerosolization of bacteria)
  • Avoid the use of water jets to avoid aerosolizing the droppings product which may contain bacteria.

Human Pathogen

Germ : The causative agent of psittacosis is Chlamydia psittaci of the family Chlamydiaceae, genus Chlamydia. In addition to C. psittaci, which mainly infects birds, there are other species: C. pneumonia (found in humans and horses in particular), C. percorum (in ruminants), C. abortus (in ruminants), C. caviae (in guinea pigs) and C. felis (cats). Several C. psittaci genotypes exist and are associated with different groups of birds. C. psittaci is a gram-negative bacterium with obligate intracellular growth. It is an animal-tropic species that occasionally causes infections in humans.

C. psittaci has been isolated from more than 450 species of birds and it is likely that all birds are present. Most human infections are acquired by contact with psittacines. (parrots, callopsitts and parakeets), but C. psittaci is also found in backyard and breeding animals (turkeys, ducks, geese, etc.) and in pigeons. Infection is introduced into wild bird farms or through the purchase of already infected animals.

Chlamydia is often present in Psittacidae and is almost always inapparent in poultry. It can manifest itself in a clinical picture with chills, depression, anorexia, dyspnea, diarrhea, conjunctivitis and disheveled plumage. Some infected birds die quickly, others become thinner and dehydrated. Without treatment, 10% of infected birds become asymptomatic chronic carriers.

Infected birds also shed bacteria when they are asymptomatic. Any infected bird, even if treated, may present a risk of human and avian contagion. In these circumstances, culling of infected birds should be encouraged. Several studies in poultry populations have reported a prevalence of C. psittaci infection of 5-8%. This prevalence can reach 100% in stressful situations, such as transport, overcrowding and intensive livestock farming.

Physical-chemical resistance

C. psittaci is sensitive to heat and conventional disinfectants (e.g. bleach, 70% alcohol). On the other hand, the germ is resistant to low temperatures and desiccation. Protected by excrement or dried nasal secretions, the bacterium can survive for months at a time. room temperature.


The germ enters the body through the upper respiratory tract and is found in the pulmonary alveoli. C. psittaci is carried by macrophages in the liver and spleen where it multiplies before gaining other organs by blood transfusion. At the level of the lung cells, an inflammatory lymphocytic response occurs with filling of the alveolar space by fluid, red blood cells and lymphocytes. The alveolar walls are edematous, necrotic, sometimes hemorrhagic. The respiratory epithelium of the bronchi and bronchioles is normally intact.

In Dogs

Emerging zoonoses also affect domestic animals. Dogs can become infected with C. psittaci if they eat the feces of a bird. They are also likely to become infected by inhalation.

In Cats

The infection is sometimes latent and animals may excrete the bacteria in their nasal secretions, urine and feces for months. These excretions are dispersed into the air in the form of aerosols. Other modes of transmission include the bite of an infected bird, mouth-to-mouth contact and feather handling. Rare cases of cat-borne psittacosis have been reported.

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