scholarly journals Estimating within-flock transmission rate parameter for H5N2 highly pathogenic avian influenza virus in Minnesota turkey flocks during the 2015 epizootic

2019 ◽  
Vol 147 ◽  
Author(s):  
A. Ssematimba ◽  
S. Malladi ◽  
T. J. Hagenaars ◽  
P. J. Bonney ◽  
J. T. Weaver ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Highly Pathogenic Avian Influenza ◽  
Transmission Rate ◽  
Mortality Data ◽  
Rate Parameter ◽  
Daily Mortality ◽  
Highly Pathogenic ◽  
Pathogenic Avian Influenza ◽  
Generalised Linear Mixed Model ◽  
Back Calculation

AbstractBetter control of highly pathogenic avian influenza (HPAI) outbreaks requires deeper understanding of within-flock virus transmission dynamics. For such fatal diseases, daily mortality provides a proxy for disease incidence. We used the daily mortality data collected during the 2015 H5N2 HPAI outbreak in Minnesota turkey flocks to estimate the within-flock transmission rate parameter (β). The number of birds in Susceptible, Exposed, Infectious and Recovered compartments was inferred from the data and used in a generalised linear mixed model (GLMM) to estimate the parameters. Novel here was the correction of these data for normal mortality before use in the fitting process. We also used mortality threshold to determine HPAI-like mortality to improve the accuracy of estimates from the back-calculation approach. The estimated β was 3.2 (95% confidence interval (CI) 2.3–4.3) per day with a basic reproduction number of 12.8 (95% CI 9.2–17.2). Although flock-level estimates varied, the overall estimate was comparable to those from other studies. Sensitivity analyses demonstrated that the estimated β was highly sensitive to the bird-level latent period, emphasizing the need for its precise estimation. In all, for fatal poultry diseases, the back-calculation approach provides a computationally efficient means to obtain reasonable transmission parameter estimates from mortality data.

scholarly journals Inferring within-flock transmission dynamics of highly pathogenic avian influenza (H5N8) in France, 2020

2020 ◽  
Author(s):  
Timothée Vergne ◽  
Simon Gubbins ◽  
Claire Guinat ◽  
Billy Bauzile ◽  
Mattias Delpont ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Sequential Monte Carlo ◽  
Highly Pathogenic Avian Influenza ◽  
Transmission Rate ◽  
Credible Interval ◽  
Transmission Dynamics ◽  
Mortality Data ◽  
Model Parameters ◽  
Highly Pathogenic ◽  
Pathogenic Avian Influenza

Following the emergence of highly pathogenic avian influenza (H5N8) in France in early December 2020, we used duck mortality data of the index case to investigate within-flock transmission dynamics. A stochastic epidemic model was adjusted to the daily mortality data and model parameters were estimated using an approximate Bayesian computation sequential Monte Carlo (ABC-SMC) algorithm. Results suggested that the virus was introduced 4 days (95% credible interval: 3 – 5) prior to the day suspicion was reported and that the transmission rate was 3.7 day-1 (95%CI: 2.6 – 5.3). On average, ducks started being infectious 3.1 hours (95%CI: 0.4 – 8.0) after infection and remained infectious for 4.4 days (95%CI: 3.1 – 5.6). Model outputs also suggested that the number of infectious ducks was already 3239 (95%CI: 26 – 3706) the day before suspicion, emphasising the substantial latent threat this virus could pose to other poultry farms and to neighbouring wildlife. These estimations can be applied to upcoming outbreaks and made available to veterinary services within few hours. This study illustrates how mechanistic models can provide rapid relevant insights to contribute to the management of infectious disease outbreaks of farmed animals.

scholarly journals Mortality Levels and Production Indicators for Suspicion of Highly Pathogenic Avian Influenza Virus Infection in Commercially Farmed Ducks

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1498
Author(s):  
Armin R. W. Elbers ◽  
José L. Gonzales
Keyword(s):  
Avian Influenza ◽  
Water Intake ◽  
Egg Production ◽  
Highly Pathogenic Avian Influenza ◽  
Severe Disease ◽  
Influenza Virus Infection ◽  
False Alarms ◽  
Daily Mortality ◽  
Highly Pathogenic ◽  
Pathogenic Avian Influenza

(1) Background: Highly pathogenic avian influenza (HPAI) is a viral infection characterized by inducing severe disease and high levels of mortality in gallinaceous poultry. Increased mortality, drop in egg production or decreased feed or water intake are used as indicators for notification of suspicions of HPAI outbreaks. However, infections in commercial duck flocks may result in mild disease with low mortality levels, thereby compromising notifications. (2) Methods: Data on daily mortality, egg production, feed intake and water intake from broiler and breeder duck flocks not infected (n = 56 and n = 11, respectively) and infected with HPAIV (n = 13, n = 4) were used for analyses. Data from negative flocks were used to assess the baseline (daily) levels of mortality and production parameters and to identify potential threshold values for triggering suspicions of HPAI infections and assess the specificity (Sp) of these thresholds. Data from infected flocks were used to assess the effect of infection on daily mortality and production and to evaluate the sensitivity (Se) of the thresholds for early detection of outbreaks. (3) Results: For broiler flocks, daily mortality > 0.3% (after the first week of production) or using a regression model for aberration detection would indicate infection with Se and Sp higher than 80%. Drops in mean daily feed or water intake larger than 7 g or 14 mL (after the first week of production), respectively, are sensitive indicators of infection but have poor Sp. For breeders, mortality thresholds are poor indicators of infection (low Se and Sp). However, a consecutive drop in egg production larger than 9% is an effective indicator of a HPAI outbreak. For both broiler and breeder duck flocks, cumulative average methods were also assessed, which had high Se but generated many false alarms (poor Sp). (4) Conclusions: The identified reporting thresholds can be used to update legislation and provide guidelines to farmers and veterinarians to notify suspicions of HPAI outbreaks in commercial duck flocks.

scholarly journals Estimating the day of highly pathogenic avian influenza (H7N7) virus introduction into a poultry flock based on mortality data

2007 ◽  
Vol 38 (3) ◽  
pp. 493-504 ◽  
Author(s):  
Marian E.H. Bos ◽  
Michiel Van Boven ◽  
Mirjam Nielen ◽  
Annemarie Bouma ◽  
Armin R.W. Elbers ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Highly Pathogenic Avian Influenza ◽  
Mortality Data ◽  
Highly Pathogenic ◽  
Pathogenic Avian Influenza ◽  
Poultry Flock

scholarly journals First detection of highly pathogenic avian influenza virus in Norway

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Knut Madslien ◽  
Torfinn Moldal ◽  
Britt Gjerset ◽  
Sveinn Gudmundsson ◽  
Arne Follestad ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Influenza A ◽  
Highly Pathogenic Avian Influenza ◽  
Wild Birds ◽  
Zoonotic Potential ◽  
Active Monitoring ◽  
Main Hypothesis ◽  
Highly Pathogenic ◽  
Pathogenic Avian Influenza ◽  
Poultry Farms

Abstract Background Several outbreaks of highly pathogenic avian influenza (HPAI) caused by influenza A virus of subtype H5N8 have been reported in wild birds and poultry in Europe during autumn 2020. Norway is one of the few countries in Europe that had not previously detected HPAI virus, despite widespread active monitoring of both domestic and wild birds since 2005. Results We report detection of HPAI virus subtype H5N8 in a wild pink-footed goose (Anser brachyrhynchus), and several other geese, ducks and a gull, from south-western Norway in November and December 2020. Despite previous reports of low pathogenic avian influenza (LPAI), this constitutes the first detections of HPAI in Norway. Conclusions The mode of introduction is unclear, but a northward migration of infected geese or gulls from Denmark or the Netherlands during the autumn of 2020 is currently our main hypothesis for the introduction of HPAI to Norway. The presence of HPAI in wild birds constitutes a new, and ongoing, threat to the Norwegian poultry industry, and compliance with the improved biosecurity measures on poultry farms should therefore be ensured. [MK1]Finally, although HPAI of subtype H5N8 has been reported to have very low zoonotic potential, this is a reminder that HPAI with greater zoonotic potential in wild birds may pose a threat in the future. [MK1]Updated with a sentence emphasizing the risk HPAI pose to poultry farms, both in the Abstract and in the Conclusion-section in main text, as suggested by Reviewer 1 (#7).

scholarly journals Differential Diagnosis for Highly Pathogenic Avian Influenza Virus Using Nanoparticles Expressing Chemiluminescence

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1274
Author(s):  
Jihee Kim ◽  
Jae-Yeon Park ◽  
Jihoon Ryu ◽  
Hyun-Jin Shin ◽  
Jung-Eun Park
Keyword(s):  
Avian Influenza ◽  
Fluorescent Protein ◽  
Highly Pathogenic Avian Influenza ◽  
Systemic Disease ◽  
Renilla Luciferase ◽  
Highly Pathogenic ◽  
Pathogenic Avian Influenza ◽  
Pathogenic Avian Influenza Virus ◽  
Green Fluorescent ◽  
Transmembrane Serine Protease

Highly pathogenic avian influenza (HPAI) virus is a causative agent of systemic disease in poultry, characterized by high mortality. Rapid diagnosis is crucial for the control of HPAI. In this study, we aimed to develop a differential diagnostic method that can distinguish HPAI from low pathogenic avian influenza (LPAI) viruses using dual split proteins (DSPs). DSPs are chimeras of an enzymatic split, Renilla luciferase (RL), and a non-enzymatic split green fluorescent protein (GFP). Nanoparticles expressing DSPs, sialic acid, and/or transmembrane serine protease 2 (TMPRSS2) were generated, and RL activity was determined in the presence of HPAI or LPAI pseudotyped viruses. The RL activity of nanoparticles containing both DSPs was approximately 2 × 106 RLU, indicating that DSPs can be successfully incorporated into nanoparticles. The RL activity of nanoparticles containing half of the DSPs was around 5 × 101 RLU. When nanoparticles containing half of the DSPs were incubated with HPAI pseudotyped viruses at low pH, RL activity was increased up to 1 × 103 RLU. However, LPAI pseudotyped viruses produced RL activity only in the presence of proteases (trypsin or TMPRSS2), and the average RL activity was around 7 × 102 RLU. We confirmed that nanoparticle fusion assay also diagnoses authentic viruses with specificity of 100% and sensitivity of 91.67%. The data indicated that the developed method distinguished HPAI and LPAI, and suggested that the diagnosis using DSPs could be used for the development of differential diagnostic kits for HPAI after further optimization.

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