Fukui Daisuke, Nakamura Makiko, Yamaguchi Tsuyoshi, Takenaka Makiko, Murakami Mami, Yanai Tokuma, Fukushi Hideto, Yanagida Kazumi, Bando Gen, Matsuno Keita, Nagano Masashi, Tsubota Toshio
1 Sapporo Crow Research Group, 2-1-804, Toyohira 3-jo, 11-chome, Toyohira-ku, Sapporo, Hokkaido 062-0903, Japan.
2 Asahikawa Municipal Asahiyama Zoological Park and Wildlife Conservation Center, Kuranauma, Higashiasahikawa-cho, Asahikawa, Hokkaido 078-8205, Japan.
J Wildl Dis. 2016 Apr 28;52(2):230-41. doi: 10.7589/2015-07-172. Epub 2016 Mar 11.
In 2006-10, an epizootic of emerging avian pox occurred in Carrion Crows ( Corvus corone ) and Large-billed Crows ( Corvus macrorhynchos ), leading to mortality of juvenile crows in Hokkaido, the northernmost island of Japan. We diagnosed 27 crows with proliferative skin lesions (19 carcasses and eight biopsied cases [one in zoo captivity]) as avian pox clinically, histopathologically by detection of Avipoxvirus-specific 4b core protein (P4b) gene, and epidemiologically. The fatal cases demonstrated intensively severe infection and aggressive lesions with secondary bacterial infection. Since the first identification of avian pox in Sapporo, Japan, in 2006, the frequency of mortality events has increased, peaking in 2007-08. Mortalities have subsequently occurred in other areas, suggesting disease expansion. In Sapporo, prevalence of avian pox evaluated by field censuses during 2007-12 was 17.6% (6.6-27.2%), peaked during 2007-08 and 2008-09, and then decreased. All diseased crows were juveniles, except for one adult. The number of crows assembling in the winter roosts had been stable for >10 yr; however, it declined in 2007-08, decreased by about 50% in 2008-09, and recovered to the previous level in 2009-10, correlated with the avian pox outbreak. Thus, avian pox probably contributed to the unusual crow population decline. All P4b sequences detected in six specimens in Sapporo were identical and different from any previously reported sequences. The sequence detected in the zoo-kept crow was distinct from any reported clades, and interspecies transmission was suspected. This report demonstrates an emerging novel avian pox in the Japanese avifauna and in global populations of Carrion Crows and Large-billed Crows. Longitudinal monitoring is needed to evaluate its impact on the crow population.
2006年至2010年期间，日本最北部岛屿北海道的小嘴乌鸦（Corvus corone）和大嘴乌鸦（Corvus macrorhynchos）暴发了新出现的禽痘疫情，导致雏鸦死亡。我们临床上、通过检测禽痘病毒特异性4b核心蛋白（P4b）基因进行组织病理学诊断以及从流行病学角度，将27只患有增殖性皮肤病变的乌鸦（19具尸体和8例活检病例[1例为圈养在动物园的乌鸦]）诊断为禽痘。致死病例表现为严重感染以及伴有继发性细菌感染的侵袭性病变。自2006年在日本札幌首次发现禽痘以来，死亡事件的频率有所增加，在2007年至2008年达到峰值。随后在其他地区也出现了死亡情况，表明疾病在扩散。在札幌，2007年至2012年期间通过野外普查评估的禽痘患病率为17.6%（6.6% - 27.2%），在2007年至2008年以及2008年至2009年达到峰值，随后下降。除1只成年乌鸦外，所有患病乌鸦均为雏鸦。在冬季栖息地聚集的乌鸦数量在超过10年的时间里一直稳定；然而，在2007年至2008年有所下降，在2008年至2009年减少了约50%，并在2009年至2010年恢复到先前水平，这与禽痘疫情相关。因此，禽痘可能是导致乌鸦种群异常减少的原因。在札幌的6个样本中检测到的所有P4b序列均相同，且与之前报道的任何序列不同。在动物园饲养的乌鸦中检测到的序列与任何已报道的分支不同，怀疑存在种间传播。本报告证明了在日本鸟类以及全球小嘴乌鸦和大嘴乌鸦种群中出现了一种新的禽痘。需要进行纵向监测以评估其对乌鸦种群的影响。
