Avian influenza outbreaks have been occurring on smallholder poultry farms in Asia for two decades. Farmer responses to these outbreaks can slow down or accelerate virus transmission. We used a longitudinal survey of 53 small scale chicken farms in southern Vietnam to investigate the impact of outbreaks of diseases with mortality on harvest rate, vaccination, and disinfection behaviors. We found that in small broiler flocks (<17 birds/flock) the estimated probability of harvest was 56% higher when an outbreak occurred, and 214% higher if an outbreak with sudden deaths occurred in the same month. Vaccination and disinfection were strongly positively correlated with flock size and farm size, respectively. Smallholder farmers (the overwhelming majority of poultry producers in low income countries) tend to rely on rapid sale of birds to mitigate losses from diseases. As depopulated birds are sent to markets or trading networks, this reactive behavior has the potential to enhance onward transmission.

中文翻译：

---

家禽饲养者对小农耕作系统中疾病暴发的反应

禽流感在亚洲的小农家禽饲养场中已经爆发了二十年。农民对这些暴发的反应可能会减慢或加速病毒传播。我们对越南南部的53个小型养鸡场进行了纵向调查，以调查疾病爆发和死亡率对收成率，疫苗接种和消毒行为的影响。我们发现，在小型肉鸡群（每只鸡群少于17羽）中，爆发时估计的收获几率高出56％，如果在同一月份发生突然死亡的爆发时，则收获几率高出214％。疫苗接种和消毒分别与鸡群规模和农场规模呈正相关。小农户（低收入国家的绝大多数家禽生产者）倾向于依靠快速出售禽类来减轻疾病造成的损失。随着人口减少的鸟类被送往市场或交易网络，这种反应性行为可能会增强传播的潜力。