Abstract

The poultry sector contributes four percent to the national GDP of Nepal. However, this sector is under threat with periodic outbreaks of Avian Influenza (AI) subtypes H5 and H9 since 2009. This has been both a public health threat and an economic issue. Since the past few years, outbreaks of AI subtype H9 have caused huge economic losses in major poultry producing areas of Nepal. However, the risk factors associated with these outbreaks have not been assessed. A retrospective case-control study was conducted from April 2018 to May 2019 to understand the risk factors associated with AI subtype H9 outbreaks in Kathmandu valley. Out of 100 farms selected, 50 were “case” farms, confirmed positive to H9 at Central Veterinary Laboratory, Kathmandu, and another 50 farms were “control” farms, matched for farm size and locality within a radius of three km from the case farm. Each farm was visited to collect information using a semi-structured questionnaire. Twelve potential risk factors were included in the questionnaire under the broad categories: birds and farm characteristics, and management and biosecurity status of the farms. Univariable and multivariable logistic regression analysis was conducted and corresponding odds ratios were calculated. Risk factors, associated with AI subtype H9 outbreaks in Kathmandu valley, identified in the final multivariable model were: “farms that have flock size greater than median flock size of study farms (>1500)” (OR = 4.41, 95% CI: 1.53–12.71, p = 0.006), “farms that did not apply rules to wear boots for visitors inside the farms” (OR = 4.32, 95% CI: 1.52–12.29, p = 0.006) and “other commercial farms located within one km periphery” (OR = 10, 95% CI: 1.8–50, p = 0.007). This study showed that outbreaks of AI subtype H9 in Kathmandu valley were associated with a higher population of birds in the farm, poor management practices, and weak biosecurity measures in poultry farms. We suggest improving management practices and increase biosecurity in the farms to reduce incidences of AI subtype H9 outbreaks in Kathmandu valley.

Highlights

  • Avian Influenza viruses (AIV) type A, belongs to Orthomyxoviridae family that can infect a wide range of species, though their known natural hosts are aquatic and wild birds [1,2]

  • The objective of this study is to identify the risk factors associated with AI subtype H9 outbreaks in Kathmandu valley

  • Under the bird and farm characteristics category: out of five variables tested, two variables: flock size of greater than 1500 (OR = 2.25, 95% confidence intervals (CIs): 1.01–5.01, p = 0.047) and farms located within a km

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Summary

Introduction

Avian Influenza viruses (AIV) type A, belongs to Orthomyxoviridae family that can infect a wide range of species, though their known natural hosts are aquatic and wild birds [1,2]. HPAI is caused by AIV subtypes H5 or H7 but not all H5 and H7 are highly pathogenic [3]. The subtype H9N2 circulating in the Eurasian region has caused huge economic losses to the poultry industry, owing to a decline in egg production and high mortality when associated with other infections [6]. As this virus has human-like receptor specificity [7], it possesses the potential to transmit to humans, posing a public health threat [8]. It has been recognized recently that AI subtype H9 had shared gene segments to the highly zoonotic virus such as H7N9 that might contribute in the emergence of influenza pandemic [9,10]

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