Chlamydiaspecies in free-living Cattle Egret (Bubulcus ibis) and Hoopoe (Upupa epops) in Egypt

A Review of Chlamydial Infections in Wild Birds

The Chlamydia are a globally distributed genus of bacteria that can infect and cause disease in a range of hosts. Birds are the primary host for multiple chlamydial species. The most well-known of these is Chlamydia psittaci, a zoonotic bacterium that has been identified in a range of wild and domesticated birds. Wild birds are often proposed as a reservoir of Chlamydia psittaci and potentially other chlamydial species. The aim of this review is to present the current knowledge of chlamydial infections in wild avian populations. We focus on C. psittaci but also consider other Chlamydiaceae and Chlamydia-related bacteria that have been identified in wild birds. We summarise the diversity, host range, and clinical signs of infection in wild birds and consider the potential implications of these infections for zoonotic transmission and avian conservation. Chlamydial bacteria have been found in more than 70 species of wild birds, with the greatest chlamydial diversity identified in Europe. The Corvidae and Accipitridae families are emerging as significant chlamydial hosts, in addition to established wild hosts such as the Columbidae. Clarifying the effects of these bacteria on avian host fitness and the zoonotic potential of emerging Chlamydiales will help us to understand the implications of these infections for avian and human health.

Efficacy of a prepared tissue culture-adapted vaccine against Chlamydia psittaci experimentally in mice

Background and Aim

Chlamydia psittaci is an intracellular pathogen with a broad range of hosts and endemic in nearly all bird species as well as many mammalian species. Outbreaks contribute to economic losses, especially due to infection of pet birds, poultry, and livestock. Worse, the organism has a zoonotic effect, and transmission to humans results in severe illness. Therefore, proper control measures need to be applied. We conducted a trial for the preparation and evaluation of inactivated vaccine against C. psittaci.

Materials and Methods

Three C. psittaci strains (accession nos.: KP942827, KP942828, and KP942829) were grown in embryonated chicken eggs and then propagated for purification in Vero cells. The immunization experiment was experimentally performed in mice, which then were challenged with a virulent C. psittaci strain.

Results

The immunization trial revealed nearly 100% protection after the challenge. The histopathological and immunofluorescence examinations of internal organs revealed that the prepared killed vaccines can effectively reduce chlamydial infection and shedding in animals with the proper level of protection.

Conclusion

Our vaccine can be used to control economic and financial losses resulting from avian chlamydiosis, especially those in poultry industries. The zoonotic transmission risk highlights the need for proper control measures.

Risk factors associated with Chlamydia psittaci infections in psittacine birds and bird handlers

AIMS

The aim of this study was to determine the prevalence and potential risk factors associated with Chlamydia psittaci infections in psittacine birds and bird handlers in Egypt.

METHODS AND RESULTS

A total of 190 swabs were collected from psittacine birds (n = 120) and bird handlers (n = 70) and were tested by polymerase chain reaction to detect the C. psittaci ompA gene. Chlamydia psittaci DNA was detected in 63 (52·5%) of 120 samples collected from psittacine birds. The occurrence of C. psittaci infections was high in Cockatiel birds (60%), followed by Fischer's lovebird (51%) and Rosy-faced lovebird (47·5%). Bird age, location (pet markets and households), housing (caged and aviary), and sampling season were considered significant risk factors for C. psittaci infections in psittacine birds. Of the 70 sputum swabs collected from bird handlers, only 4 (6%) were positive for C. psittaci. Positive cases were closely associated with older persons (≥30 years) who had respiratory signs and handled birds in pet markets. Further, wearing protective gloves and washing hands when handling psittacine birds decreased the frequency of C. psittaci infections in bird handlers.

CONCLUSIONS

The prevalence of C. psittaci infections in psittacine birds in Egypt is high, which has a potential threat to human health in this area. Thus, dissemination of effective prevention and control measures is essential to prevent the spread of C. psittaci among psittacine birds, as well as among humans in contact with birds.

SIGNIFICANCE AND IMPACT OF THE STUDY

Results from this study highlighted the risk factors associated with C. psittaci infections in psittacine birds and bird handlers in Egypt and will aid in developing prevention and control measures to reduce the risk of C. psittaci infection.