Elbers A R W, Holtslag J B, Bouma A, Koch G
Department of Virology, Central Institute for Animal Disease Control, Wageningen University and Research Centre, Houtribweg 39, 8221 RA Lelystad, The Netherlands.
Avian Dis. 2007 Mar;51(1 Suppl):304-8. doi: 10.1637/7579-040106R.1.
Daily within-flock mortality data, from a few days before until a few days after onset of increased mortality, from H7N7-infected flocks were analyzed with nonlinear regression for layer (organic and free-range or caged), broiler, and turkey flocks. The following notification thresholds were recommended for The Netherlands: 1) organic layer flocks, broiler flocks, and turkey flocks < or = 11 wk of age: > or = 0.5% mortality/day for two consecutive days; 2) layer flocks with birds housed in cages: > or = 0.25% mortality/day for two consecutive days; 3) turkey flocks > or = 16 wk of age: > or = 1% mortality/day for two consecutive days. Notification of increased mortality to the veterinary authorities should take place on the second day of increased mortality. Interpretation of mortality thresholds should be on the level of the poultry barn in which clinical problems arise. Because of nonoptimal specificity of proposed thresholds (mortality possibly caused by other diseases), use of PCR-diagnostics (results within 24 hr) without costs to the individual farmer should be promoted to exclude avian influenza in suspect clinical situations in order to minimize negative economic consequence for farmers and stimulate notification by farmers and veterinary practitioners.
对感染H7N7的蛋鸡群（有机养殖、散养或笼养）、肉鸡群和火鸡群，从死亡率增加前几天到死亡率增加后几天的每日鸡群内死亡率数据进行了非线性回归分析。为荷兰推荐了以下通报阈值：1）有机蛋鸡群、肉鸡群和11周龄及以下的火鸡群：连续两天死亡率≥0.5%/天；2）笼养蛋鸡群：连续两天死亡率≥0.25%/天；3）16周龄及以上的火鸡群：连续两天死亡率≥1%/天。死亡率增加应在第二天向兽医当局通报。死亡率阈值的解释应基于出现临床问题的禽舍层面。由于所提议阈值的特异性欠佳（死亡率可能由其他疾病引起），应推广免费向个体养殖户提供的PCR诊断方法（24小时内出结果），以便在疑似临床情况下排除禽流感，从而尽量减少对养殖户的负面经济影响，并促使养殖户和兽医从业者进行通报。
