Emergence of a Novel Avian Pox Disease in British Tit Species

Abstract

Avian pox is a viral disease with a wide host range. In Great Britain, avian pox in birds of the Paridae family was first diagnosed in a great tit (Parus major) from south-east England in 2006. An increasing number of avian pox incidents in Paridae have been reported each year since, indicative of an emergent infection. Here, we utilise a database of opportunistic reports of garden bird mortality and morbidity to analyse spatial and temporal patterns of suspected avian pox throughout Great Britain, 2006–2010. Reports of affected Paridae (211 incidents) outnumbered reports in non-Paridae (91 incidents). The majority (90%) of Paridae incidents involved great tits. Paridae pox incidents were more likely to involve multiple individuals (77.3%) than were incidents in non-Paridae hosts (31.9%). Unlike the small wart-like lesions usually seen in non-Paridae with avian pox in Great Britain, lesions in Paridae were frequently large, often with an ulcerated surface and caseous core. Spatial analyses revealed strong clustering of suspected avian pox incidents involving Paridae hosts, but only weak, inconsistent clustering of incidents involving non-Paridae hosts. There was no spatial association between Paridae and non-Paridae incidents. We documented significant spatial spread of Paridae pox from an origin in south-east England; no spatial spread was evident for non-Paridae pox. For both host clades, there was an annual peak of reports in August/September. Sequencing of the avian poxvirus 4b core protein produced an identical viral sequence from each of 20 great tits tested from Great Britain. This sequence was identical to that from great tits from central Europe and Scandinavia. In contrast, sequence variation was evident amongst virus tested from 17 non-Paridae hosts of 5 species. Our findings show Paridae pox to be an emerging infectious disease in wild birds in Great Britain, apparently originating from viral incursion from central Europe or Scandinavia.

Diversity of avipoxviruses in captive-bred Houbara bustard

“…Interestingly, the parent strains from both subclades B1 and B2 (group of isolates CNPV/Chlamydotis macqueenii/MA/012/2010 and CNPV/Chlamydotis undulata/MA/025/2011, respectively) are the only ones isolated in the 3 Houbara breeding projects and their P4b sequences are identical to those of strains isolated from house sparrows in Morocco [37]. Moreover, the P4b sequence of the subclade B1 parent is identical to a strain distributed worldwide and that has been more especially isolated from great tits in Europe and associated with the emergence of APV infections in this species [13,14]. It can be hypothesized that this is a unique B1 strain that may have the ability to effectively and sustainably infect a wide diversity of avian hosts.…”

“…In wild birds, the infection can compromise survival and breeding success by decreasing the ability to escape predators [9], to fledge and rear chicks [10], by impairing the pairing success [11] or by increasing mortality [12]. Recently, emergence of APV infections in great tits in Europe and especially in the UK has been described and could represent a threat for the species [13,14]. The impact of the disease can be dramatic for endangered species, especially for island species when APV are introduced in naïve populations as described in Hawaii [15], the Galapagos Islands [16] or Canary islands [17].…”

Garden Bird Feeding: Insights and Prospects from a North-South Comparison of This Global Urban Phenomenon

“…Moreover, numerous other diseases may be similarly spread because of the interactions of birds at feeders. These include salmonellosis and Avian Pox, highlighting the importance of thorough and frequent cleaning of feeders as best practice when feeding birds (Lawson et al, 2012b). Despite the severity of these outbreaks, and the relatively high level of publicity associated with them, relationships between feeders and disease remain remarkably under-studied.…”

Worldwide Phylogenetic Relationship of Avian Poxviruses

“…Avian pox has also been identified as a risk factor in the reintroduction programs of houbara bustard (Chlamydotis undulata macqueenii) in the Middle East, Floreana mockingbirds (Mimus trifasciatus) in Galapagos (15,16), and peregrine falcons (Falco peregrinus) in Germany (17). The recent emergence of an epizootic of conspicuous and distinctive avian pox among great tits (Parus major) in the United Kingdom (18), and its penetrance of a historically wellstudied population near Oxford, allowed detailed study of the epidemiology (19) and population-level impacts (20) of the disease in wild birds.…”