Pathogenicity of an H5N1 Highly Pathogenic Avian Influenza Virus Isolated in the 2010–2011 Winter in Japan to Mandarin Ducks

Abstract

ABSTRACT. Widespread outbreaks of highly pathogenic avian influenza (HPAI) caused by H5N1 viruses occurred in wild birds in Japan from 2010-2011. Forty out of 63 deceased wild birds belonged to the order Anseriformes, and mandarin duck was one of the dominant species. To estimate the risk of mandarin ducks as a source of virus infection in the environment, we examined the pathogenicity of a causal H5N1 HPAI virus to mandarin ducks. About half of the mandarin ducks died by inoculation with 10 7.0 TCID 50 of A/mandarin duck/ Miyazaki/22M807-1/2011 (H5N1). Viruses were mainly recovered from the trachea of the ducks sacrificed at three days post inoculation (d.p.i.). Viruses were recovered from the laryngopharyngeal swabs of the observation group until 5 d.p.i. In ducks that died at the late phase of infection, viruses were detected in the systemic organs, such as lung, kidney and colon. Together, these results showed that the H5N1 HPAI viruses, which belonged to clade 2.3.2.1 and are mainly circulating in East Asia, were lethal to mandarin ducks, indicating that mandarin ducks have the potential to disseminate the virus to other bird species. Therefore, wild birds should be kept out of poultry farms to prevent HPAI outbreaks in the future. KEY WORDS: H5N1, influenza virus, mandarin duck, pathogenicity.

Influenza A virus infection in Japanese wild boars (<i>Sus scrofa leucomystax</i>)

“…In Yamaguchi, two outbreaks occurred in 2004 and 2014 near the area where wild boars were captured [5, 10]. AIV H5N1 is thought to be transferred by birds migrating from the Asian continent to Japan and has been introduced into poultry farms, causing lethal infections [17]. Therefore, we suspected that AIV H5N1 might be more prevalent in Japan, including at Yamaguchi.…”

Pathogenicity of an H5N1 avian influenza virus isolated in Vietnam in 2012 and reliability of conjunctival samples for diagnosis of infection

“…Most of the ducks dying from infection showed neurological signs, suggesting that the death of these ducks was likely to be associated with damage in the central nervous system. The results obtained in this study seem to be consistent with the previous studies performed for the H5N1 HPAIV of clade 2.3.2.1 isolated from wild birds until 2011 (Kwon at al., 2011; Sakoda et al, 2010; Soda et al, 2013), confirming that the H5N1 isolate of clade 2.3.2.1 could cause illness and death in a large proportion of domestic ducks.…”

“…In 2012, viruses of clade 2.3.2.1 were dominantly circulating in Vietnam. Several studies reported on the pathogenicity of H5N1 viruses of clade 2.3.2.1, which were isolated from wild birds until 2011 (Kwon et al, 2011; Sakoda et al, 2010; Soda et al, 2013). However, pathogenicity of the H5N1 HPAIV isolated from domestic ducks in Vietnam in 2012 has not been studied.…”

Risk Prediction of Three Different Subtypes of Highly Pathogenic Avian Influenza Outbreaks in Poultry Farms: Based on Spatial Characteristics of Infected Premises in South Korea

“…For example, the H5N8 subtype occurring in 2014–2016 caused relatively mild clinical symptoms in duck species, compared with the H5N6 subtype in the 2016–2017 epidemic ( 19 ). In contrast, the H5N1 subtype that affected poultry holdings during the 2010–2011 epidemic was lethal to domestic ducks ( 20 ). Furthermore, the basic reproduction number, which estimates the average number of infectees by a single infector, was the highest in H5N1 compared to subtype H5N8 and H5N6 ( 21 ).…”