Detection of Chlamydophila psittaci by RT-PCR method

Transmission of Ch. psittaci infection

Infection occurrence

Clinical signs

Diagnostics

Treatment

Measures and prevention

Chlamydia (Chlamydiae) is an intracellular parasite occurring in humans and many kinds of animals. Chlamydia has not its own ATP system and it uses the ATP of the host cell for its metabolic processes and therefore is also called energy parasite.

Transmission of Ch. psittaci infection

Ch. psittaci causes infection in birds, mammals and humans. Ch. psittaci is transmitted from host to host mainly by air. The infectious elementary bodies of Ch. psittaci are substantially more resistant to drying in comparison with other species so that they can survive in bird secretions for several months. This enables horizontal transmission of infection even without direct contact with the infected animal. Avian strains isolated from more than 100 bird species cause avian chlamydiosis in these avian hosts. The avian chlamydiosis is common among parrots, pigeons and poultry. The chlamydias are spread from the infected bird into the environment by nasal and ocular secretions, excrements and feather dust. A vertical transmission via eggs to chickens has also been proven.  Ch. psittaci can be transmitted to a human and has therefore a zoonotic potential. Humans are most often infected by inhalation of contaminated dust; frequently direct contact with an infected bird was proved.  
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Infection occurrence

The disease is more likely to occur in large-scale breeding, brooders and poultry farms. Risky locations are bird and poultry exhibitions and sale points.
The infection is rare in humans and was found mainly in poultry farm workers, breeders of exotic birds or veterinarians.
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Clinical signs

The incubation period of chlamydiosis in birds is usually 3-10 days, but can be longer. Latent infections are common and active form of the infection can occur even several years after exposure. Stress-activated latent infections are obviously common in captive birds, where it spreads among the other individuals.  
The clinical signs depend on the strain of the organism and the species of the host and its conditions. The infections caused by Ch. psittaci may be asymptomatic or result in mild to severe clinical signs with high mortality. In most case, the signs are non-specific - such as lethargy, inappetence, loss of weight, ruffled feathers.
However, some birds may develop respiratory (rhinitis, sinusitis, keratoconjunctivitis, dyspnoea, respiratory murmur) and gastrointestinal signs (in birds with affected liver and kidneys, watery and greenish droppings may be seen) and occasionally neurological signs such as tremors, opisthotonos, paresis of legs may occur.  
X-ray shows hepatomegaly (enlarged liver), splenomegaly (enlarged spleen), opacity and airsacculitis.
Zoonosis (human infection) manifests itself with respiratory problems, the most frequent sing is atypical pneumonia, but neuritis, hepatitis or myocarditis may occur as well. The incubation period is usually 7-14 days; the course of disease is often similar to the cold or the flu. Endangered are particularly person with decreased immunity.
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Diagnostics

The spectrum of diagnostic methods includes a number of techniques for direct proof of infectious agents (e.g. PCR, cultivation methods) and indirect proof by serological methods (e.g. ELISA, proof of antibodies by immunofluorescence).  
The Genomia laboratory performs direct determination of Chlamydophila psittaci in a sample by real-time PCR method. It is a highly sensitive and reliable method that detects the presence of DNA of Chlamydophila psittaci.
The examination by the real-time PCR can be performed on a sample of cloacal swabs, choan swabs or blood.  In post mortem cases, examinations of liver, kidney and spleen tissues can be performed.

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Treatment

The infection caused by Chlamydophila psittaci is treated by antibiotics (e.g. doxycycline, OTC, CTC). The most often used antibiotics are tetracyclines. The treatment is chosen by a veterinarian and in case of zoonosis a specialised doctor.
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Measures and prevention

All birds that have been in contact with a positive individual are to be considered as potentially infected and have to be placed into quarantine. In case of separation, it is necessary to provide a special place and equipment/aids for the infected birds and if possible, even other keepers.  In infected animals, it is necessary to minimize stress situations and administer supporting therapy. As preventive measure, it is recommended to buy birds from certified breeds and to keep new birds in the quarantine as necessary or exclude the presence of the pathogen by test. The recommended observation period is up to 90 days. In some cases, preventive treatment by administration of antibiotics is possible. It is also necessary to observe hygienic rules and ensure sufficient air circulation.