Fallah Mehrabadi M H, Bahonar A R, Vasfi Marandi M, Sadrzadeh A, Tehrani F, Salman M D
Department of Poultry Viral Diseases, Razi Vaccine and Serum Research Institute, Karaj, Iran.
Department of Food Hygiene & Quality Control, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Prev Vet Med. 2016 Jun 1;128:1-5. doi: 10.1016/j.prevetmed.2016.01.031. Epub 2016 Feb 2.
In almost all villages in Iran backyard birds, especially chickens, are kept for egg and meat production. AI H9N2 subtype is endemic in Iran. Therefore, estimation of AI prevalence among these birds is important to determine the risk of transmission of infection to commercial farms. The aim of this study was to estimate subclinical infections or previous exposure to H5, H7, and H9 subtypes and to identify potentially important determinants of prevalence of this infectious at premises level in backyard poultry, bird gardens, zoos, and wild bird markets in Iran. A survey was conducted using a cross-sectional design throughout the entire country. A total of 329 villages, seven bird gardens, three zoos and five wild bird markets were included. In each village four families that kept birds were included in the collection of biological samples and background information. The Enzyme-Linked Immunosorbent Assay (ELISA) was used as the screening test and all ELISA-positive samples were examined with the HI test to differentiate H5, H7, and H9. Among the bird gardens, eight of 15 premises (53.3%) were positive in both the ELISA test and HI for H9N2. Testing of samples collected in the villages revealed that 296 out of 329 villages (90%) had positive ELISA tests and also HI tests for H9. The HI-H9 mean titers in positive units were significantly higher than negative units (P<.001). This study revealed no significant statistical differences between risk variables in seropositive and seronegative bird gardens in the case of H9 (P>.05). The results of this study showed that among the risk variables, mountainous area was a protective factor and lack of hygienic disposal of dead birds was a risk factor for AI; this was also observed in rural poultry. The high sero-prevalence of influenza H9N2 in rural domestic poultry indicates that the disease is endemic. It is necessary to include backyard poultry in any surveillance system and control strategy due to the existence of AIV in backyard poultry and the possibility of transmission of infection to commercial poultry farms. Implementation of an AI surveillance program and biosecurity measures can be useful to control this infection and prevent AI from spreading to commercial farms. Furthermore in Iran there is no program for destruction of birds infected with the H9N2, so an effective vaccination program with regard to issues such as acceptability and cost-benefit must play an important role in reducing infections in backyard poultry.
在伊朗，几乎所有村庄都饲养后院家禽，尤其是鸡，用于产蛋和肉用。H9N2亚型禽流感在伊朗呈地方流行性。因此，评估这些家禽中的禽流感流行情况对于确定感染传播至商业养殖场的风险至关重要。本研究的目的是评估亚临床感染或既往对H5、H7和H9亚型的暴露情况，并确定伊朗后院家禽场、鸟类园、动物园和野生鸟类市场中该传染病流行率的潜在重要决定因素。采用横断面设计在全国范围内开展了一项调查。共纳入329个村庄、7个鸟类园、3个动物园和5个野生鸟类市场。在每个村庄，选取4个饲养家禽的家庭采集生物样本并收集背景信息。采用酶联免疫吸附测定（ELISA）作为筛查试验，所有ELISA阳性样本均用血凝抑制试验（HI）检测，以区分H5、H7和H9。在鸟类园中，15个场所中有8个（53.3%）在ELISA试验和H9N2的HI检测中均呈阳性。对在村庄采集的样本进行检测发现，329个村庄中有296个（90%）ELISA试验和H9的HI检测均呈阳性。阳性单位的HI-H9平均滴度显著高于阴性单位（P<0.001）。本研究显示，在H9方面，血清阳性和血清阴性鸟类园的风险变量之间无显著统计学差异（P>0.05）。本研究结果表明，在风险变量中，山区是一个保护因素，病死禽无害化处理缺乏是禽流感的一个风险因素；在农村家禽中也观察到了这一点。农村家鸡中H9N2流感的高血清流行率表明该疾病呈地方流行性。鉴于后院家禽中存在禽流感病毒且有感染传播至商业家禽养殖场的可能性，有必要将后院家禽纳入任何监测系统和防控策略。实施禽流感监测计划和生物安全措施有助于控制这种感染并防止禽流感传播至商业养殖场。此外，在伊朗没有针对感染H9N2的禽类的扑杀计划，因此，一个关于可接受性和成本效益等问题的有效疫苗接种计划必须在减少后院家禽感染方面发挥重要作用。
