Sharma G K, Mahajan S, Matura R, Biswal J K, Ranjan R, Subramaniam S, Misri J, Bambal R G, Pattnaik B
ICAR-Project Directorate on Foot and Mouth Disease, Mukteswar Nainital, India.
ICAR-Krishi Bhawan, New Delhi, India.
Transbound Emerg Dis. 2017 Aug;64(4):1133-1147. doi: 10.1111/tbed.12478. Epub 2016 Feb 26.
A systematic vaccination programme is ongoing in India to control the three prevailing serotypes (A, O, Asia1) of foot-and-mouth disease (FMD) virus. Under the programme, more than 120 million bovine (term bovine applicable to both cattle and buffalo in this study) population of 221 of the 666 districts in the country are being bi-annually vaccinated with trivalent vaccine since 2010. Although clinical disease has reduced in these districts because of the systematic vaccinations, an abrupt increase in the number of FMD cases was recorded in 2013. Hence, a longitudinal field study was conducted in the year 2014 to estimate the serological herd immunity level in bovines, the impact of systematic vaccinations and field efficacy of the vaccines used. Serum samples (n = 115 963) collected from 295 districts of the 18 states of the country were analysed to estimate antibody titres against structural proteins of the three serotypes. The efficacy of the vaccine was demonstrated in the control group (group-D) where animals of the group were identified by ear tags for the purpose of repeated sampling after vaccination. Progressive building of the herd immunity in the field after systematic vaccination was demonstrated. The mean antibody titre against the serotypes O, A and Asia1 was estimated as log 1.93 (95% CI 1.92-1.93), 2.02 (2.02-2.02) and 2.02 (2.02-2.02), respectively, in the states covered under the control programme. However, in other states herd immunity was significantly low [mean titre log 1.68 (95% CI 1.67-1.69), 1.77 (1.76-1.78) and 1.85 (1.84-1.86) against the three serotypes]. Inverse relationship between the herd immunity and FMD incidences was observed the states following different vaccination practices. The study helped in demarcation of FMD risk zones in the country with low herd immunity. Estimation of herd immunity kinetics in the field helped in refining the vaccination schedule under the control programme.
印度正在开展一项系统性疫苗接种计划，以控制口蹄疫（FMD）病毒的三种流行血清型（A、O、亚洲1型）。根据该计划，自2010年以来，该国666个区中的221个区的1.2亿多头牛（本研究中“牛”一词适用于牛和水牛）每两年接种一次三价疫苗。尽管由于系统性疫苗接种，这些区的临床疾病有所减少，但2013年口蹄疫病例数却突然增加。因此，2014年开展了一项纵向实地研究，以评估牛群的血清学免疫水平、系统性疫苗接种的影响以及所用疫苗的现场效力。对从该国18个邦的295个区采集的血清样本（n = 115 963）进行分析，以估计针对三种血清型结构蛋白的抗体滴度。在对照组（D组）中证明了疫苗的效力，该组动物通过耳标进行识别，以便在接种疫苗后进行重复采样。证明了系统性疫苗接种后现场牛群免疫力的逐步建立。在控制计划覆盖的邦中，针对O、A和亚洲1型血清型的平均抗体滴度分别估计为log 1.93（95%CI 1.92 - 1.93）、2.02（2.02 - 2.02）和2.02（2.02 - 2.02）。然而，在其他邦，牛群免疫力显著较低[针对三种血清型的平均滴度分别为log 1.68（95%CI 1.67 - 1.69）、1.77（1.76 - 1.78）和1.85（1.84 - 1.86）]。在采用不同疫苗接种做法的邦中，观察到牛群免疫力与口蹄疫发病率之间呈负相关。该研究有助于划分该国牛群免疫力较低的口蹄疫风险区。对现场牛群免疫动力学的估计有助于完善控制计划下的疫苗接种时间表。
