Elbers A R W, Fabri T H F, de Vries T S, de Wit J J, Pijpers A, Koch G
Department of Virology, Central Institute for Animal Disease Control-Lelystad (CIDC-Lelystad), P.O. Box 2004, 8203 AA Lelystad, The Netherlands.
Avian Dis. 2004 Sep;48(3):691-705. doi: 10.1637/7149.
Clinical signs and gross lesions observed in poultry submitted for postmortem examination (PME) from the first five infected poultry flocks preceding the detection of the primary outbreak of highly pathogenic avian influenza (HPAI) of subtype H7N7 during the 2003 epidemic in the Netherlands are described. The absence of HPAI from the Netherlands for more than 75 yr created a situation in which poultry farmers and veterinary practitioners did not think of AI in the differential diagnosis as a possible cause of the clinical problems seen. Increased and progressive mortality was not reported to the governmental authorities by farmers or veterinary practitioners. It took 4 days from the first entry of postmortem material to notify the governmental authorities of a strong suspicion of an AI outbreak on the basis of a positive immunofluoresence test result. The gross lesions observed at PME did not comply with the descriptions in literature, especially the lack of hemorrhagic changes in tissues, and the lack of edema and cyanosis in comb and wattles is noted. The following lessons are learned from this epidemic: a) in the future, increased and progressive mortality should be a signal to exclude AI as cause of disease problems on poultry farms; b) intensive contact between the veterinary practitioner in the field and the veterinarian executing PME is necessary to have all relevant data and developments at one's disposal to come to a conclusive diagnosis; c) in an anamnesis, reporting of high or increased mortality should be quantified in the future (number of dead birds in relation to the number of birds brought to the farm to start production, together with the timing within the production cycle), or else this mortality cannot be interpreted properly; d) if clinical findings such as high mortality indicate the possibility of HPAI, the pathologist should submit clinical samples to the reference laboratory, even if PME gives no specific indications for HPAI; e) the best way to facilitate early detection of an HPAI outbreak is to have the poultry farmer and/or veterinary practitioner immediately report to the syndrome-reporting system currently in operation the occurrence of high mortality, a large decrease in feed or water intake, or a considerable drop in egg production; f) in order to detect low pathogenic avian influenza infections that could possibly change to HPAI, a continuous serologic monitoring system has been set up, in which commercial poultry flocks are screened for antibodies against AI virus of subtypes H5 and H7.
本文描述了在2003年荷兰疫情期间，高致病性H7N7亚型禽流感（HPAI）首次爆发之前，提交进行尸检（PME）的前五批感染家禽群中观察到的临床症状和大体病变。荷兰已75多年未出现HPAI，这使得家禽养殖户和兽医在鉴别诊断时未将禽流感视为临床问题的可能病因。养殖户或兽医未向政府当局报告死亡率增加和不断上升的情况。从首次送检尸检材料到根据免疫荧光检测阳性结果向政府当局通报强烈怀疑禽流感爆发，历时4天。尸检时观察到的大体病变与文献描述不符，特别是组织中缺乏出血性变化，鸡冠和肉垂缺乏水肿和发绀。从这次疫情中吸取了以下教训：a）未来，死亡率增加和不断上升应作为排除禽流感作为家禽场疾病问题病因的信号；b）现场兽医与进行尸检的兽医之间进行密切接触是必要的，以便掌握所有相关数据和进展情况，从而做出确定性诊断；c）在病史采集中，未来应量化高死亡率或死亡率增加的报告（死亡禽鸟数量与引入农场开始生产的禽鸟数量相关，并结合生产周期内的时间），否则无法正确解释这种死亡率；d）如果高死亡率等临床发现表明可能存在HPAI，病理学家应将临床样本提交给参考实验室，即使尸检未给出HPAI的具体指征；e）促进早期发现HPAI爆发的最佳方法是让家禽养殖户和/或兽医立即向当前运行的综合征报告系统报告高死亡率、饲料或水摄入量大幅下降或产蛋量大幅下降的情况；f）为了检测可能转变为HPAI的低致病性禽流感感染，已建立了一个连续血清学监测系统，对商业家禽群进行H5和H7亚型禽流感病毒抗体筛查。
