Persistence of Avian Influenza Virus (H5N1) in Feathers Detached from Bodies of Infected Domestic Ducks

Abstract

Asian lineage highly pathogenic avian influenza virus (H5N1) continues to cause mortality in poultry and wild bird populations at a panzootic scale. However, little is known about its persistence in contaminated tissues derived from infected birds. We investigated avian influenza virus (H5N1) persistence in feathers detached from bodies of infected ducks to evaluate their potential risk for environmental contamination. Four-week-old domestic ducks were inoculated with different clades of avian influenza virus (H5N1). Feathers, drinking water, and feces were collected on day 3 postinoculation and stored at 4°C or 20°C. Viral persistence in samples was investigated for 360 days by virus isolation and reverse transcription-PCR. Infectious viruses persisted for the longest period in feathers, compared with drinking water and feces, at both 4°C and 20°C. Viral infectivity persisted in the feathers for 160 days at 4°C and for 15 days at 20°C. Viral titers of 10 4.3 50% egg infectious doses/ml or greater were detected for 120 days in feathers stored at 4°C. Viral RNA in feathers was more stable than the infectivity. These results indicate that feathers detached from domestic ducks infected with highly pathogenic avian influenza virus (H5N1) can be a source of environmental contamination and may function as fomites with high viral loads in the environment.

Challenges for accurate and prompt molecular diagnosis of clades of highly pathogenic avian influenza H5N1 viruses emerging in Vietnam

“…between 2 and 5 days post inoculation, with the virus titres in feather samples being greater than or comparable with those in swabs at the majority of corresponding time points. In one infected duck, H5N1 HPAI-positive feathers were observed up to 8 days post inoculation, and viral antigen was detected immunohistochemically in the feather epidermal cells in the calamus (Yamamoto et al, 2008). High viral titres were also demonstrated in feathers collected from H5N1 HPAI-infected Pekin ducks, and infectivity of at least 10 4.3 median embryo infective dose/ml was shown to persist for at least 100 days in feather tissue stored at 48C (Yamamoto et al, 2010).…”

“…In the present study, feathers were collected from chickens and ducks at four H5N1 HPAIinfected locations when clinical signs were apparent, and in such disease scenarios the testing of feathers may be a highly practicable approach for HPAI RRT-PCR diagnosis. Yamamoto et al (2008) infected three Pekin ducks with a clade 2.2 H5N1 HPAI virus and observed no clinical signs other than corneal opacity. Presence of virus was demonstrated in feathers in all three ducks Table 3.…”

“…In one infected duck, H5N1 HPAI-positive feathers were observed up to 8 days post inoculation, and viral antigen was detected immunohistochemically in the feather epidermal cells in the calamus (Yamamoto et al, 2008). High viral titres were also demonstrated in feathers collected from H5N1 HPAI-infected Pekin ducks, and infectivity of at least 10 4.3 median embryo infective dose/ml was shown to persist for at least 100 days in feather tissue stored at 48C (Yamamoto et al, 2010). While there is an attraction to sampling feathers in suspect HPAI poultry settings where mortality and morbidity is evident (Soliman et al, 2010), a rationale for feather sampling still requires investigation during the early pre-clinical stages of HPAI infection.…”

“…Clinical specimens obtained from chickens and ducks were tested by virus isolation (VI) in embryonated fowls' eggs (EFEs) (EU, 2006;OIE, 2010b). Samples included swabs and feathers, the latter having been shown to be a good sample for the detection of H5N1 HPAI virus (Yamamoto et al, 2008). In addition to VI, RNA extracts from clinical specimens were tested by validated AI RRT-PCRs, which have emerged in recent years as highly sensitive and specific methods for the generic identification of AI (matrix [M]-gene RRT-PCR) and the specific molecular subtyping of H5 AI viruses by testing RNA extracted directly from clinical specimens (Hoffmann et al, 2009).…”

Climate change suggests a shift of H5N1 risk in migratory birds

“…The result indicated that the transmission efficiency of HPAI H5N1 among poultry was 1.7 times higher in regions where infected wild birds had been detected compared with regions without infected wild birds (Keawcharoen et al, 2011). In addition, waterfowl may transfer the virus mechanically during long distance migration, and feathers infected with HPAI H5N1 could also be a source of environmental contamination with high viral loads (Uriarte et al, 2011;Yamamoto et al, 2010).…”