Infected or not: are PCR-positive oropharyngeal swabs indicative of low pathogenic influenza A virus infection in the respiratory tract of Mallard Anas platyrhynchos?

Wille, Michelle; Run, Peter van; Waldenström, Jonas; Kuiken, Thijs

doi:10.1186/1297-9716-45-53

Cited by 16 publications

(19 citation statements)

References 28 publications

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“…A similar observation has been described previously in chickens [23]. One potential explanation for the one quail that only shed on 7 DPI is that the apparent shedding observed in this animal was simply associated with the ingestion of virusladen water [20], as viral RNA was detected on several DPI in the water bowls of both quail cages (Table 2). However, this explanation appears unlikely for the second quail that failed to seroconvert, as this bird shed during 6-9 DPI, and shed in greater quantities than its cage-mate, which was the only other quail shedding on 6 DPI ( Table 1).…”

Section: Discussionsupporting

confidence: 86%

Transmission of H6N2 wild bird-origin influenza A virus among multiple bird species in a stacked-cage setting

et al. 2017

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Live bird markets are common in certain regions of the U.S. and in other regions of the world. We experimentally tested the ability of a wild bird influenza A virus to transmit from index animals to naïve animals at varying animal densities in stacked cages in a simulated live bird market. Two and six mallards, five and twelve quail, and six and nine pheasants were used in the low-density and high-density stacks of cages, respectively. Transmission did not occur in the high-density stack of cages likely due to the short duration and relatively low levels of shedding, a dominance of oral shedding, and the lack of transmission to other mallards in the index cage. In the low-density stack of cages, transmission occurred among all species tested, but not among all birds present. Oral and cloacal shedding was detected in waterfowl but only oral shedding was identified in the gallinaceous birds tested. Overall, transmission was patchy among the stacked cages, thereby suggesting that chance was involved in the deposition of shed virus in key locations (e.g., food or water bowls), which facilitated transmission to some birds.

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Section: Discussionsupporting

confidence: 86%

Transmission of H6N2 wild bird-origin influenza A virus among multiple bird species in a stacked-cage setting

et al. 2017

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“…Fecal samples, on average, contained a larger amount of viral RNA than cloacal swabs, possibly as a consequence of the fact that fecal samples contained more material from the beginning. A question that still needs attention is whether positive detection in oropharyngeal samples proves actual replication, as a recent study in mallards found no evidence for replication of LPAI virus in the oropharyngeal tract even if there was a positive detection by molecular techniques in the birds (31). Nevertheless, different hosts (i.e., taxonomic groups) may vary in predominant replication sites based on differential expression of viral receptors, and at the same time, different virus strains can vary in tissue tropism, like the HPAI H5N1virus, which replicates primarily in the respiratory tract (12,13).…”

Section: Discussionmentioning

confidence: 99%

How Does Sampling Methodology Influence Molecular Detection and Isolation Success in Influenza A Virus Field Studies?

Latorre‐Margalef

Avril

Tolf

et al. 2016

Appl Environ Microbiol

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Wild waterfowl are important reservoir hosts for influenza A virus (IAV) and a potential source of spillover infections in other hosts, including poultry and swine. The emergence of highly pathogenic avian influenza (HPAI) viruses, such as H5N1 and H5N8, and subsequent spread along migratory flyways prompted the initiation of several programs in Europe, North America, and Africa to monitor circulation of HPAI and low-pathogenicity precursor viruses (low-pathogenicity avian influenza [LPAI] viruses). Given the costs of maintaining such programs, it is essential to establish best practice for field methodologies to provide robust data for epidemiological interpretation. Here, we use long-term surveillance data from a single site to evaluate the influence of a number of parameters on virus detection and isolation of LPAI viruses. A total of 26,586 samples (oropharyngeal, fecal, and cloacal) collected from wild mallards were screened by real-time PCR, and positive samples were subjected to isolation in embryonated chicken eggs. The LPAI virus detection rate was influenced by the sample type: cloacal/fecal samples showed a consistently higher detection rate and lower cycle threshold (C t ) value than oropharyngeal samples. Molecular detection was more sensitive than isolation, and virus isolation success was proportional to the number of RNA copies in the sample. Interestingly, for a given C t value, the isolation success was lower in samples from adult birds than in those from juveniles. Comparing the results of specific real-time reverse transcriptase (RRT)-PCRs and of isolation, it was clear that coinfections were common in the investigated birds. The effects of sample type and detection methods warrant some caution in interpretation of the surveillance data.T he number of studies focusing on the role of wild birds as reservoir species for influenza A virus (IAV) has increased dramatically over the last 10 years (1). This increase was to a large extent caused by the emergence of a highly pathogenic avian influenza (HPAI) virus of the H5N1 subtype in Southeast Asia in 1999 (2). This particular virus causes high mortality in domestic poultry and can be transmitted among wild birds, particularly waterfowl. It rapidly reached a large spatial distribution in Asia, Europe, and Africa in 2006 and has remained endemic in parts of this range. Several surveillance programs were initiated in response to the H5N1 spread (3), but standardized methods were not implemented everywhere. In addition, the emergence in Southeast Asia of other IAV subtypes in poultry and in humans, like H5N1 and H7N9, and the recent spread of H5N8 into Europe and North America (4, 5), point to the need for efficient and reliable screening methods (6). As IAV is an RNA virus and is sensitive to changes in the physical environment, such as temperature, pH, and salinity (7, 8), sampling and screening strategies need to be evaluated in order to provide best practice.Traditionally, IAV surveillance has been based on cloacal swabs or fresh droppings (here c...

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“…We performed one‐step rRT‐PCR to screen for influenza A virus by targeting the matrix (M) gene, and all influenza A‐positive samples were further subjected to rRT‐PCR for H5 subtyping using H5a‐ and H5b‐specific primers and probes as previously described . A sample was considered positive for detection of influenza A virus RNA if the cycle of threshold ( C t ) was lower than 40 . We did not attempt to test for H9, H7, or other subtypes of influenza as our focus was on the H5 subtype which has occurred commonly in Bangladesh.…”

Section: Methodsmentioning

confidence: 99%

“…31 A sample was considered positive for detection of influenza A virus RNA if the cycle of threshold (C t ) was lower than 40. 32 We did not attempt to test for H9, H7, or other subtypes of influenza as our focus was on the H5 subtype which has occurred commonly in Bangladesh.…”

Section: H5 Antibody Detection By Competitive Enzyme-linked Immunosmentioning

confidence: 99%

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An epidemiological study of avian influenza A (H5) virus in nomadic ducks and their raising practices in northeastern Bangladesh, 2011‐2012

Sarkar

Khan

Mikolon

et al. 2017

Influenza Resp Viruses

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BackgroundIn Bangladesh, nomadic duck flocks are groups of domestic ducks reared for egg production that are moved to access feeding sites beyond their owners’ village boundaries and are housed overnight in portable enclosures in scavenging areas. The objectives of this study were to measure the prevalence of influenza A virus RNA and H5‐specific antibodies in nomadic ducks and to characterize nomadic duck raising practices in northeastern Bangladesh.MethodsWe tested duck egg yolk specimens by competitive ELISA to detect antibodies against avian influenza A (H5) and environmental fecal samples by real‐time reverse‐transcription polymerase chain reaction (rRT‐PCR) to detect influenza A virus RNA and H5 subtype.ResultsThe median age of the ducks was 24 months (range: 8‐36 months) and the median flock size was 300 ducks (range: 105‐1100). Of 1860 egg yolk samples, 556 (30%, 95% confidence interval (CI): 28‐32) were positive for antibodies against H5 and 58 flocks (94%) had at least one egg with H5‐specific antibodies. Of 496 fecal samples, 121 (24%, 95% CI: 22‐29) had detectable influenza A RNA. Thirty‐three flocks (53%) had at least one fecal sample positive for influenza A RNA.ConclusionsNomadic ducks in Bangladesh are commonly infected with avian influenza A (H5) virus and may serve as a bridging host for transmission of avian influenza A (H5) virus or other avian influenza A viruses subtypes between wild waterfowl, backyard poultry, and humans in Bangladesh.

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Infected or not: are PCR-positive oropharyngeal swabs indicative of low pathogenic influenza A virus infection in the respiratory tract of Mallard Anas platyrhynchos?

Cited by 16 publications

References 28 publications

Transmission of H6N2 wild bird-origin influenza A virus among multiple bird species in a stacked-cage setting

Transmission of H6N2 wild bird-origin influenza A virus among multiple bird species in a stacked-cage setting

How Does Sampling Methodology Influence Molecular Detection and Isolation Success in Influenza A Virus Field Studies?

An epidemiological study of avian influenza A (H5) virus in nomadic ducks and their raising practices in northeastern Bangladesh, 2011‐2012

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