National Institute of Virology, Microbial Containment Complex, 130/1, Sus Road, Pashan, Pune, 411021, India.
Virol J. 2012 Aug 7;9:151. doi: 10.1186/1743-422X-9-151.
More than 70 outbreaks of the highly pathogenic avian influenza (HPAI) H5N1 have been reported in poultry in the western and north-eastern parts of India. Therefore, in view of the recent HPAI H5N1 outbreaks in poultry, active AI surveillance encompassing wild, resident, migratory birds and poultry was undertaken during 2009-2011 in the State of West Bengal.
A total of 5722 samples were collected from West Bengal; 3522 samples (2906 fecal droppings + 616 other environmental samples) were from migratory birds and 2200 samples [1604 tracheal, cloacal swabs, environmental samples, tissue samples + 596 blood (serum)] were from domestic ducks and poultry. All tracheal, cloacal and environmental samples were processed for virus isolation. Virus isolates were detected using hemagglutination assay and identified using hemagglutination inhibition (HI) and reverse transcriptase polymerase chain reaction (RT-PCR) assays. Sequencing and phylogenetic analysis of partial region of the hemagglutinin and neuraminidase genes was done. Intravenous pathogenicity index assays were performed in chickens to assess pathogenicity of AI virus isolates. Serum samples were tested for detection of antibodies against AI viruses using HI assay.
A total of 57 AI H9N2, 15 AI H4N6 and 15 Newcastle Disease (NDV) viruses were isolated from chickens, from both backyard and wet poultry markets; AI H4N6 viruses were isolated from backyard chickens and domestic ducks. Characterization of AI H9N2 and H4N6 viruses revealed that they were of low pathogenicity. Domestic ducks were positive for antibodies against H5 and H7 viruses while chickens were positive for presence of antibodies against AI H9N2 and NDV.
In the current scenario of HPAI H5N1 outbreaks in West Bengal, this report shows presence of low pathogenic AI H9N2 and H4N6 viruses in chickens and domestic ducks during the period 2009-2011. This is the first report of isolation of H4N6 from India. Antibodies against AI H5 and H7 in ducks highlight the probable role of domestic ducks in the transmission of AI viruses. Human infections of H9N2 have been reported from China and Hong Kong. This necessitates implementation of prevention and control measures to limit the spread of AI viruses.
在印度西部和东北部，已报告发生了 70 多起高致病性禽流感（HPAI）H5N1 疫情，主要涉及家禽。因此，鉴于最近在印度西孟加拉邦发生的家禽高致病性禽流感 H5N1 疫情，在 2009-2011 年期间，对该邦的野生、留鸟、候鸟和家禽开展了主动的 AI 监测。
从西孟加拉邦共采集了 5722 份样本；其中 3522 份（2906 份粪便+616 份其他环境样本）来自候鸟，2200 份[1604 份气管、泄殖腔拭子、环境样本、组织样本+596 份血清]来自家养鸭和家禽。所有气管、泄殖腔和环境样本均进行病毒分离。采用血凝试验检测病毒分离株，采用血凝抑制（HI）和逆转录聚合酶链反应（RT-PCR）试验鉴定。对血凝素和神经氨酸酶基因部分区域进行测序和系统进化分析。用鸡进行静脉致病性指数试验，以评估 AI 病毒分离株的致病性。用 HI 试验检测血清样本中针对 AI 病毒的抗体。
从来自后院和湿禽市场的鸡中分离到了 57 株 AI H9N2、15 株 AI H4N6 和 15 株新城疫（NDV）病毒；后院鸡和家养鸭中分离到了 AI H4N6 病毒。AI H9N2 和 H4N6 病毒的特征表明它们的致病性较低。家养鸭对 H5 和 H7 病毒呈抗体阳性，而鸡对 AI H9N2 和 NDV 呈抗体阳性。
在西孟加拉邦目前的高致病性禽流感 H5N1 疫情情况下，本报告显示，2009-2011 年期间，低致病性 AI H9N2 和 H4N6 病毒在家禽和家养鸭中流行。这是印度首次分离到 H4N6 病毒。鸭对 AI H5 和 H7 的抗体提示，家养鸭可能在 AI 病毒的传播中发挥作用。中国和香港报告了人感染 H9N2 的病例。这需要实施预防和控制措施，以限制 AI 病毒的传播。
