Department of Livestock Services, Central Veterinary Laboratory, Kathmandu, Nepal.
Institute of Agriculture and Animal Science, Tribhuvan University, Kathmandu, Nepal.
PLoS One. 2020 Apr 2;15(4):e0223550. doi: 10.1371/journal.pone.0223550. eCollection 2020.
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.
尼泊尔的家禽业占国民生产总值的 4%。然而，自 2009 年以来，周期性爆发的禽流感（AI）亚型 H5 和 H9 对该行业构成了威胁。这既是公共卫生威胁，也是经济问题。在过去的几年中，H9 亚型 AI 的爆发给尼泊尔主要家禽生产地区造成了巨大的经济损失。然而，尚未评估与这些疫情相关的风险因素。2018 年 4 月至 2019 年 5 月期间，开展了一项回顾性病例对照研究，以了解加德满都谷地 H9 亚型 AI 爆发的相关风险因素。在选择的 100 个农场中，50 个是“病例”农场，在加德满都中央兽医实验室证实为 H9 阳性，另外 50 个是“对照”农场，按农场规模和距离病例农场 3 公里范围内的位置进行匹配。每个农场都使用半结构式问卷进行了访问，以收集信息。问卷涵盖了鸟类和农场特征、农场管理和生物安全状况等广泛类别的 12 个潜在风险因素。进行了单变量和多变量逻辑回归分析，并计算了相应的比值比。在最终的多变量模型中，与加德满都谷地 H9 亚型 AI 爆发相关的风险因素包括：“拥有大于研究农场中位数禽群规模的禽群的农场（>1500）”（OR=4.41，95%CI：1.53-12.71，p=0.006），“未执行访客在农场内穿靴子规定的农场”（OR=4.32，95%CI：1.52-12.29，p=0.006）和“一千米范围内其他商业农场”（OR=10，95%CI：1.8-50，p=0.007）。本研究表明，加德满都谷地 H9 亚型 AI 的爆发与农场中鸟类数量较多、管理不善和家禽农场生物安全措施薄弱有关。我们建议改善管理实践并加强农场的生物安全措施，以减少加德满都谷地 H9 亚型 AI 爆发的发生。
