CHARACTERIZATION OF AVIAN POXVIRUS IN ANNA'S HUMMINGBIRD (CALYPTE ANNA) IN CALIFORNIA, USA

Abstract

Avian poxvirus (genus Avipoxvirus, family Poxviridae) is an enveloped double-stranded DNA virus that may be transmitted to birds by arthropod vectors or mucosal membrane contact with infectious particles. We characterized the infection in Anna's Hummingbird (Calypte anna; n = 5 birds, n = 9 lesions) by conducting diagnostic tests on skin lesions that were visually similar to avian poxvirus lesions in other bird species. Skin lesions were single or multiple, dry and firm, pink to yellow, with scabs on the surface, and located at the base of the bill, wings, or legs. Microscopically, the lesions were characterized by epidermal hyperplasia and necrosis with ballooning degeneration, and intracytoplasmic inclusions (Bollinger bodies) in keratinocytes. The 4b core gene sequence of avian poxvirus was detected by PCR in samples prepared from lesions. Nucleotide sequences were 75-94% similar to the sequences of other published avian poxvirus sequences. Phylogenetic analyses showed that the Anna's Hummingbird poxvirus sequence was distinguished as a unique subclade showing similarities with sequences isolated from Ostrich (Struthio camelus), Wild Turkey (Meleagris gallopavo), falcons (Falco spp.), Black-browed Albatross (Diomedea melanophris), Mourning Dove (Zenaida macroura) and White-tailed Eagle (Haliaeetus albicilla). To our knowledge this is the first published report of definitive laboratory diagnosis of avian poxvirus in a hummingbird. Our results advance the science of disease ecology in hummingbirds, providing management information for banders, wildlife rehabilitators, and avian biologists.

Clinical findings and normative ocular data for free‐living Anna's (Calypte anna) and Black‐chinned (Archilochus alexandri) Hummingbirds

“…Poxviral ocular disease is the most common ocular manifestation of viral disease in birds 42,43 and has been described in over 230 species of birds including hummingbirds. 20,[44][45][46][47][48][49] In most avian species, disease arising from poxvirus infection is typically mild and rarely causes mortality. 20,50 However, poxvirus lesions can be severe and affect the wings, beak, feet, or legs and lead to increased risk of predation, secondary infections, changes in behavior, and reduced reproductive success.…”

“…20,[44][45][46][47][48][49] In most avian species, disease arising from poxvirus infection is typically mild and rarely causes mortality. 20,50 However, poxvirus lesions can be severe and affect the wings, beak, feet, or legs and lead to increased risk of predation, secondary infections, changes in behavior, and reduced reproductive success. 20,[50][51][52][53][54] Although poxvirus infection does not always result in ocular lesions, and infrequently results in intraocular disease, devastating residual ocular disease including corneal disease, uveitis, cataract, and phthisis bulbi can occur and lead to blindness.…”

“…Intraocular pressure was measured in 362 eyes (183 birds; 140 Anna's and 43 Black-chinned Hummingbirds; Table 1). Mean AE SD (range) IOP for all birds was 11.12 AE 2.20 (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) Table 1). Mean AE SD (range) refractive error was +0.32 AE 0.33 (À0.25 to +1) D, with 82% of eyes being emmetropic (i.e.…”

“…14 Avian poxvirus is known to result in ocular and periocular lesions and has been isolated in Anna's Hummingbirds, but its morbidity and mortality, and overall impact on migratory and stationary populations, is unknown. 19,20 Mites and other external parasites are commonly detected in free-living hummingbird populations 14 and can also have ocular consequences (eg, chorioretinal atrophy), 21 but typically have little effect on general health. To the authors' knowledge, the prevalence of ocular disease in hummingbirds has not been reported.…”

First phylogenetic analysis of Avipoxvirus (APV) in Brazil

“…It is worldwide distributed, affecting at least 3% of 232 species of birds (Bolte et al 1999, Tripathy et al 2000, Kim et al 2003, Godoy et al 2013. APV may manifest in two different ways: lesions on the skin, commonly named as cutaneous form, and lesions in the mouth, pharynx, larynx, esophagus and trachea, called diphtheritic form.…”