An outbreak of herpesvirus infection in a flock of ringed turtle doves (Streptopelia risoria)

A retrospective study of pigeon herpesviral infection in domestic pigeons in California (1991-2014) and literature review

We characterized naturally occurring pigeon herpesvirus (PiHV; Columbid alphaherpesvirus 1) infection in domestic pigeons in California. We retrieved and analyzed 62 pathology reports produced between 1991 and 2014 at the California Animal Health and Food Safety Laboratory System. In 56 of the cases, the diagnosis of PiHV infection was established based on histopathology, either alone (44 cases) or combined with virus isolation (VI; 8), transmission electron microscopy (TEM; 3), or PCR (1); in the remaining 6 cases, the diagnosis was established based on VI (5 cases) or TEM (1) alone. PiHV infection affected 1 system in 34, 2 in 16, and ≥3 systems in 6 cases; data were not available for the remaining 6 cases. Most commonly affected was the digestive system (55 cases), followed by the respiratory tract (5) and lymphoid system (2). The liver (39 cases), crop (17), and esophagus (14) were the organs affected most commonly. Many affected cells often bore single eosinophilic intranuclear inclusion bodies. PiHV infection was a secondary diagnosis or incidental finding in 35 cases. Most (55) cases had 1 (21), or up to 4 (34), other concurrent infections; the most common concurrent infections were pigeon circoviral infection (26), trichomonosis (24), aspergillosis (11), and colibacillosis (10).

PREVALENCE OF COLUMBID HERPESVIRUS INFECTION IN FERAL PIGEONS FROM NEW SOUTH WALES AND VICTORIA, AUSTRALIA, WITH SPILLOVER INTO A WILD POWERFUL OWL (NINOX STRUENA)

Columbid herpesvirus-1 (CoHV-1) is widespread in feral pigeons in North America and Europe. We used a PCR assay to detect CoHV-1 DNA in oral and cloacal tissues and oral swabs from naturally infected pigeons. Fifty-three feral pigeons from five flocks in Australia (n=3 from south-central Victoria and n=2 from Sydney) were examined for CoHV-1 DNA. We detected CoHV-1 DNA in oral mucosa and cloacal mucosa, with higher concentrations in the oral mucosa. The sensitivity of testing oral swabs was the same as testing the tissue, indicating that testing of oral swabs from live birds is an effective means of screening flocks for CoHV-1 infection. Infection was found in all five of the flocks examined and the prevalence of infection ranged from 70% to100%. Most positive birds could be detected with a single-amplification PCR, but a nested amplification was required to detect others. Oral swabs from Australian native doves and pigeons (n=18) and the introduced Collared Dove (Streptopelia chinensis; n=2) were also tested by the nested PCR and all were negative for CoHV-1 DNA. We describe a fatal infection of CoHV-1 in a wild Powerful Owl (Ninox strenua) that was observed feeding on feral pigeons. This is the first known case of CoHV-1 causing death in a wild bird of prey in Australia. Our data suggest that CoHV-1 is widespread in feral pigeon flocks in Australia but we did not find it in native doves and pigeons. Spillover into native avian predator species may be occurring.

Sarcocystis calchasi encephalitis in a rock pigeon

A rock pigeon (Columba livia) caught in Akihabara, Tokyo, showed neurological symptoms, such as head tilt and circling. Pathological examinations revealed abundant Sarcocystic cysts in the skeletal muscle and myocardium with mild myositis, and numerous schizonts and sarcocysts with severe multifocal granulomatous T-lymphocytic infiltration in the central nervous system. A Sarcocystis calchasi-specific gene was detected in the muscle and brain. This case indicates S. calchasi was distributed in Japan and caused severe encephalitis to rock pigeons.

Respiratory herpesvirus infection in two Indian Ringneck parakeets

A flock of Indian Ringneck parakeets ( Psittacula krameri manillensis) was imported to the United States from Australia. Soon after, 1 parakeet suddenly died, and a second parakeet died after a 2-day course of illness, which consisted of anorexia, lethargy, emaciation, and dyspnea. At necropsy, the affected birds had diffuse consolidation and red discoloration of the lungs, as well as thickened, congested air sacs. The microscopic examination revealed multifocal, necrotizing bronchitis, parabronchitis, and interstitial pneumonia. The lumen of the affected airways contained numerous, large syncytial cells with up to 15 nuclei. The nuclei of these syncytial cells often contained large, eosinophilic inclusion bodies, consistent with herpesvirus. The epithelium of the trachea and air sacs was hypertrophied and contained syncytial cells with intranuclear inclusion bodies similar to the bronchi. In addition, a few intranuclear inclusion bodies were also present in the epithelial cells that line the air capillaries. On ultrastructural examination, the nuclei of degenerating epithelial cells contained clusters of viral nucleocapsid proteins and unenveloped, icosahedral, viral particles that were approximately 90 nm in diameter. In addition, some epithelial cells contained clusters of enveloped viral particles approximately 105 nm in diameter, within the cytocavitary network. These lesions are characteristic of those caused by respiratory herpesvirus of parakeets.