Detection of pigeon circovirus in cloacal swabs: implications for diagnosis, epidemiology and control

Abstract

Pigeon circovirus (picv) was detected in cloacal swab samples by means of a newly-developed, sensitive pcr. An initial investigation of 17 Belgian racing pigeons aged up to eight months showed that rates of detection of 88 per cent and above were achieved using samples of cloacal swab, blood and bursa of Fabricius. The sampling of 15 caged pigeons six times when they were from three to 31 weeks of age indicated that picv infections were more readily detected in cloacal swabs than in blood, and that the virus could be detected in cloacal swabs for longer periods after infection than in blood. picv infections were detected in cloacal swabs from 38 of 47 young pigeons aged from two to 31 weeks, from 12 racing lofts, which had clinical signs including diarrhoea and weight loss, regurgitation and respiratory signs. Samples from birds from two infected lofts indicated that picv could be detected in some birds for at least 27 weeks. Although nine of 14 pigeons aged from 32 to 45 weeks were virus-positive, picv was detected in only one of 18 adult pigeons that originated from four infected lofts.

Investigations into feather abnormalities in racing pigeons

“…It is generally believed that hematological analyses do not have high diagnostic significance in pigeon circovirosis (10). Pathological lesions are often associated with secondary infections because of an immunosuppression induced by PiCV (10,(23)(24)(25), which corresponded with our results. Moreover, we observed lymphoid depletion in lymphatic organs (mainly bursa of Fabricious), follicular atrophy of the bursa of Fabricius and the presence of intracytoplasmic botryoid inclusions, which were considered pathognomonic for pigeon circovirus infection (24).…”

“…1 year. According to the literature, PiCV poses the greatest threat for young pigeons, less than one year of age (16,25). Tavernier et al (23) reported the highest seasonal prevalence of PiCV infections between March and May.…”

“…Additionally, DNA samples from tissues were used for detection of herpesvirus (PiHV) and pigeon adenovirus (PiAdV) by PCR. Amplification primers and reaction conditions were obtained from the literature (2,15,16,25).…”

Quantification of pigeon circovirus in serum, blood, semen and different tissues of naturally infected pigeons using a real-time polymerase chain reaction

“…These results confirmed the importance of the excretion of PiCV in the droppings and explained the apparent ease with which this virus infection is propagated in the young pigeons not only within the dovecote but also between different dovecotes at the time of the first racing competitions. The detection of high virus DNA levels in cloacal swabs is also consistent with earlier results by Todd et al (2006), who showed*using a conventional PCR test*that PiCV DNA could be detected in the cloacal swabs from apparently healthy pigeons for long periods (up to 31 weeks) and from a small proportion of adult ( 1 year-old) pigeons. The detection of PiCV DNA in the serum from pigeon number 20, which was collected in 1991 in Belgium, was of interest given that PiCV infections were not diagnosed in Belgium prior to 1997 (Duchatel et al, 1998).…”

The epidemiology, molecular characterization and clinical pathology of circovirus infections in pigeons – current knowledge

“…Circovirus infections in pigeons are diagnosed by performing molecular analyses of cloacal, blood and serum samples from live birds and samples of the BF and spleen from dead birds Todd et al 2002;Roy et al 2003;Franciosini et al 2005;Todd et al 2006;Freick et al 2008;Duchatel et al 2009). The isolation of PiCV genetic material from pigeons is not always indicative of a circovirosis due to the high prevalence of subclinical infections.…”