Observations on detection, excretion and transmission of pigeon circovirus in adult, young and embryonic pigeons

Abstract

Infections with pigeon circovirus (PiCV) occur in young racing pigeons and pigeons raised for meat production and have been reported worldwide, but relatively little is known about the disease induced by PiCV infection. The aim of this study was to investigate how PiCV is transmitted. Using a sensitive polymerase chain reaction (PCR) test, the presence of PiCV was investigated in a wide range of samples from adult pigeons, embryos, breeders and young birds, which were derived from a racing loft that had a clinical history of "young pigeon sickness" and in which PiCV had been previously been diagnosed. Using PCR, PiCV DNA was detected in tissues of 13/20 apparently healthy older birds, aged from 1 to 9 years. Viral DNA was most commonly detected in the respiratory organs, including the trachea, pharynx and lung, followed by tissues such as the spleen, kidney and liver. It was also detected in the ovary and/or testes of some birds. This finding, and the detection of viral DNA in tissues from 8/22 embryos, suggested that PiCV may be vertically transmitted. Testing of pharyngeal and cloacal swabs, and blood samples, collected immediately before the death of the adult pigeons, failed to detect all birds found to be infected at necropsy, suggesting that testing of potential breeding birds would not enable exclusion of infected birds from breeding programmes. Additional PCR testing of cloacal swab samples obtained sequentially from 19 young pigeons showed that while four were excreting virus when 15 days old, only one bird was excreting at the time of weaning (28 days old). The detection of viral DNA in cloacal swab samples from 15.8% of the birds when 37 days old and 100% of birds when 51 days old suggested that most young pigeons probably became infected in the rearing loft.

Evidence of possible vertical transmission of duck circovirus

“…In both psittacine and columbid birds with circovirus infection, psittacine beak and feather disease virus (BFDV) and pigeon circovirus (PiCV) have been suspected to be probable vertical transmission (Latimer et al, 1991;Paré et al, 1999). Recently, PiCV DNA was detected in embryos before hatching, and the ovary and testis of adult birds suggesting a vertical transmission (Duchatel et al, 2006). In addition, BFDV DNA was detected in both embryonated and nonembryonated budgerigar eggs, suggesting that the BFDV can be transmitted vertically (Rahaus et al, 2008).…”

Recurrent positive selection and heterogeneous codon usage bias events leading to coexistence of divergent pigeon circoviruses

“…PiCV was first documented in Canada in 1986 (Woods et al, 1994); since then, several outbreaks have been reported in many countries, including Northern Ireland (Smyth & Carroll, 1995;Todd et al, 2001), England (Gough & Drury, 1996), Germany (Mankertz et al, 2000;Raue et al, 2005;Soike, 1997), France (Abadie et al, 2001), Belgium (Duchatel et al, 2006), China (Yu et al, 2009), Hungary (Cságola et al, 2012 and Italy (Coletti et al, 2000;Franciosini et al, 2005). A comprehensive study has demonstrated that PiCV infection is associated with a multifactorial disease known as young pigeon disease syndrome (YPDS) possibly by inducing immunosuppression in infected birds (Raue et al, 2005;Schmidt et al, 2008).…”

Occurrence and genetic diversity of pigeon circovirus strains in Poland

“…Pigeon circovirus infections are very common in the domestic pigeon population, and their clinical form occurring in young birds is called Young Pigeon Disease Syndrome (YPDS) (Smyth and Carroll, 1995;Paré et al, 1999;Raue et al, 2005;Duchatel et al, 2005Duchatel et al, , 2006Zhang et al, 2011;Cságola et al, 2012;Stenzel et al, 2012). Circoviral infection in pigeons can be manifested in a wide range of signs including weight loss, decrease in racing performance, respiratory problems, diarrhoea, and occasional problems with plumage development (Raue et al, 2005).…”