A comparison of the seroepidemiology of chlamydial infection in pigeon fanciers and farmers in the U.K

Chlamydophila psittaci in homing and feral pigeons and zoonotic transmission

Chlamydiosis is a zoonotic disease in birds caused by Chlamydophila psittaci, an obligate intracellular bacterium. There are seven known avian outer-membrane protein A genotypes, A–F and E/B. The importance of genotyping lies in the fact that certain genotypes tend to be associated with certain hosts and a difference in virulence. Genotype B is the most prevalent in pigeons, but the more virulent genotypes A and D have also been discovered. The current study assessed the prevalence of C. psittaci in 32 Belgian homing-pigeon facilities and in 61 feral pigeons captured in the city of Ghent, Belgium. Additionally, zoonotic transmission of C. psittaci was investigated in the homing-pigeon facilities. Homing pigeons were often infected, as at least one of the lofts was positive in 13 of the 32 (40.6 %) pigeon breeding facilities. Genotypes B, C and D were detected. Zoonotic transmission was discovered in 4 of the 32 (12.5 %) pigeon fanciers, revealing genotype D in two of them, whilst genotyping was unsuccessful for the other two human pharyngeal swabs. This study clearly demonstrates the possible risk of C. psittaci zoonotic transmission from homing pigeons. Pigeon fanciers often (37.5 %) used antibiotics for prevention of respiratory disease. Because of the risk of developing drug-resistant strains, regular use of antimicrobial drugs must be avoided. This study is believed to be the first to detect C. psittaci in Belgian feral pigeons. The prevalence rate in the city of Ghent was extremely low, which is beneficial for public health.

Stability of Chlamydophila pneumoniae in a harsh environment without a requirement for acanthamoebae

The effect of actual interactions between Chlamydophila pneumoniae and amoebae (Acanthamoeba) on the survival of C. pneumoniae was investigated. C. pneumoniae and amoebae were detected in 75 soil samples by IFU assay and PCR. Although C. pneumoniae could not be cultured, the DNA prevalence of C. pneumoniae and amoebae in natural soil was 20% and 92% (no correlation between the prevalence of DNA was observed). The viability of C. pneumoniae spiked in autoclaved soil was assessed by IFU assay and RT-PCR. Although the number of infective progeny decreased for three days, transcripts of C. pneumoniae were detected for up to 98 days independently of amoebae. The stability of C. pneumoniae in liquid medium was also assessed by IFU assay and transmission electron microscopy. The bacteria could survive at 15 degrees C for 14 days independently of amoebae. Bacteria cultured without amoebae were confirmed to have normal structures. Thus, the presence of amoebae has no effect on C. pneumoniae survival, and the bacteria can survive in the absence of host cells for an extended period of time.

Atypical respiratory pathogens

The main atypical pathogens in respiratory tract infections are classified on the basis of their ability to cause atypical pneumonia. This is not a well-defined clinical entity, and it is evident that atypical pathogens can sometimes cause 'typical' pneumonias and vice versa. This emphasizes the need for microbiological diagnosis, since it affects the selection of proper treatment, in which beta-lactam antibiotics and aminoglycosides are not effective. Moreover, mixed infections caused by atypical and typical pathogens together are common. At this moment rapid and sensitive diagnostic methods are lacking. Besides numerous viruses, the main bacterial pathogens causing atypical pneumonias are Mycoplasma pneumoniae, two chlamydial species, Chlamydia pneumoniae and C. psittaci, one rickettsia, Coxiella burnetti, and several Legionella species. The majority of these pathogens cause upper respiratory tract infections more often than overt pneumonias. An atypical agent, Chlamydia pneumoniae, has also been associated with chronic inflammatory conditions in the cardiovascular system. The most recently discovered pathogen in atypical pneumonias is a hantavirus causing hantavirus pulmonary syndrome.

Prevalence of Chlamydia trachomatis, Chlamydia psittaci and Chlamydia pneumoniae antibodies in blood donors and attendees of STD clinics

OBJECTIVE: To estimate the prevalence of Chlamydia trachomatis, C. psittaci and C. pneumoniae antibodies in sera from altogether 931 blood donors, patients with symptoms of urethritis, assumed salpingitis and sexually acquired reactive arthritis (SARA), and women with fertility problems. METHODS: IgG antibodies to C. trachomatis, C. psittaci and C. pneumoniae were determined by microimmunofluorescence (MIF) tests. All patients were also tested for genital C. trachomatis infection using direct immunofluorescence (DIF) tests. RESULTS: The DIF-positive cases had a significantly (p < 0.0001) higher prevalence of C. trachomatis antibodies than the DIF negatives, i.e. 88.5% versus 14% in men with urethritis, 94.3% versus 36.4% in women with salpingitis, 66.7% versus 16.7% in SARA patients and 90.6% versus 20.8% in women with fertility problems. Antibody reactivity to all three chlamydial species was found significantly (p < 0.0001) more often in the patient groups and in those with a DIF-confirmed genital C. trachomatis infection than in blood donors. CONCLUSIONS: Presence of serum antibodies to C. trachomatis is tightly associated with the presence of chlamydiae in the genital tract, which also influences the cross-reactivities occurring in the MIF tests between chlamydial species.