Cuong N V, Truc V N T, Nhung N T, Thanh T T, Chieu T T B, Hieu T Q, Men N T, Mai H H, Chi H T, Boni M F, van Doorn H R, Thwaites G E, Carrique-Mas J J, Hoa N T
Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam.
University of Science, Ho Chi Minh City, Vietnam.
Transbound Emerg Dis. 2016 Apr;63(2):127-35. doi: 10.1111/tbed.12470. Epub 2016 Jan 8.
We investigated episodes of suspected highly pathogenic avian influenza (HPAI)-like illness among 12 meat duck flocks in two districts in Tien Giang province (Mekong Delta, Vietnam) in November 2013. In total, duck samples from 8 of 12 farms tested positive for HPAI virus subtype A/haemagglutinin 5 and neuraminidase 1 (H5N1) by real-time RT-PCR. Sequencing results confirmed clade of 2.3.2.1.c as the cause of the outbreaks. Most (7/8) laboratory-confirmed positive flocks had been vaccinated with inactivated HPAI H5N1 clade 2.3.4 vaccines <6 days prior to onset of clinical signs. A review of vaccination data in relation to estimated production in the area suggested that vaccination efforts were biased towards larger flocks and that vaccination coverage was low [21.2% ducks vaccinated with two shots (range by district 7.4-34.9%)]. The low-coverage data, the experimental evidence of lack of cross-protection conferred by the currently used vaccines based on clade 2.3.4 together with the short lifespan of meat duck flocks (60-70 days), suggest that vaccination is not likely to be effective as a tool for control of H5N1 infection in meat duck flocks in the area.
2013年11月，我们对越南湄公河三角洲地区坚江省两个区的12个肉鸭群中疑似高致病性禽流感（HPAI）样疾病的发病情况进行了调查。通过实时逆转录聚合酶链反应（RT-PCR）检测，12个养殖场中有8个养殖场的鸭样本对HPAI病毒A/血凝素5和神经氨酸酶1（H5N1）亚型呈阳性。测序结果证实2.3.2.1.c分支是疫情的病因。大多数（7/8）实验室确诊的阳性鸭群在出现临床症状前不到6天接种了HPAI H5N1 2.3.4分支灭活疫苗。对该地区与估计产量相关的疫苗接种数据进行审查表明，疫苗接种工作偏向于较大的鸭群，且疫苗接种覆盖率较低[21.2%的鸭子接种了两针疫苗（各区范围为7.4 - 34.9%）]。低覆盖率数据、目前使用的基于2.3.4分支的疫苗缺乏交叉保护的实验证据以及肉鸭群寿命较短（60 - 70天），表明疫苗接种作为该地区控制肉鸭群H5N1感染的工具不太可能有效。
