Occurrence of Nonsuppurative Encephalomyelitis and Congenital Abnormalities of Calves Resulting from the Akabane Virus in Middle Hyogo Prefecture

Tomita, Keisuke; Kamomae, Masahiro; Chujo, Masaki; Miyake, Yuriko; Kohama, Namiko; Uramoto, Kyohya

doi:10.12935/jvma.64.781

Cited by 1 publication

(2 citation statements)

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“…The phylogenetic analysis indicated that the causative viruses were closely related and comprised a single lineage with the previous AKAV isolates causing outbreaks of encephalomyelitis in Japan and South Korea (Kono et al, 2008;Miyazato et al, 1989;Oem, Yoon et al, 2012) | e439 overwintered in East Asia and spread again through the western part of Japan during summer/autumn of 2011. Also, genogroup II isolates have been known to cause similar symptoms in cattle (Mitake et al, 2011;Tomita et al, 2011). However, such cases are rare, as we know from past field surveillance efforts.…”

Section: Resultsmentioning

confidence: 99%

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Transition of Akabane virus genogroups and its association with changes in the nature of disease in Japan

Yanase

Kato

Hayama

et al. 2017

Transbound Emerg Dis

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Akabane virus (AKAV) is teratogenic to the foetus of domestic ruminants and causes a significant reproduction loss in cattle in Japan. In several past epizootics in cattle, AKAV was also associated with post-natal encephalomyelitis, mainly in calves and young stock. Previously analysed AKAV isolates in East Asia form two major clusters, genogroups I and II, with isolates involved in encephalomyelitis belonging mainly to the former. Between 2007 and 2013, AKAV epizootics were regularly observed in Japan during the summer/autumn season, and abnormal deliveries and post-natal encephalomyelitis caused by the virus in cattle were reported. During this period, 30 AKAV isolates were obtained from diseased and sentinel cattle, a piglet and Culicoides biting midges throughout Japan and were subjected to genetic comparison and phylogenetic analysis with previous isolates. In 2007, 2011 and 2013, AKAV belonging to genogroup I was identified in the central nervous systems of calves showing neurological disorders. Notably, a total of 165 cases of bovine encephalomyelitis were reported in 2011 and the isolated viruses from affected animals shared high genetic identities with a South Korean isolate that was associated with a large outbreak in 2010, suggesting some epidemiological linkage between these epizootics. Epizootics of genogroup II were observed in 2008 and 2010, but bovine post-natal encephalomyelitis cases rarely occurred. Our findings suggest that the frequent incursion of genogroup I isolates has increased the frequency of post-natal encephalomyelitis cases in Japan in recent years. Infection by genogroup I virus was also identified in piglets with neurological disorders or congenital malformations in 2011 and 2013. The aetiological role of AKAV in pigs should be elucidated in the future.

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Section: Resultsmentioning

confidence: 99%

“…The virus possibly overwintered in East Asia and spread again through the western part of Japan during summer/autumn of 2011. Also, genogroup II isolates have been known to cause similar symptoms in cattle (Mitake et al., ; Tomita et al., ). However, such cases are rare, as we know from past field surveillance efforts.…”

Section: Discussionmentioning

confidence: 99%