Kumar Muthusamy Santhosh, Kamaraj Pattabi, Khan Siraj Ahmed, Allam Ramesh Reddy, Barde Pradip V, Dwibedi Bhagirathi, Kanungo Suman, Mohan Uday, Mohanty Suman Sundar, Roy Subarna, Sagar Vivek, Savargaonkar Deepali, Tandale Babasaheb V, Topno Roshan Kamal, Kumar Chethrapilly P Girish, Sabarinathan Ramasamy, Kumar Velusamy Saravana, Bitragunta Sailaja, Grover Gagandeep Singh, Lakshmi Pinnaka V M, Mishra Chandra Mauli, Sadhukhan Provash, Sahoo Prakash Kumar, Singh Shivendra K, Yadav Chander Prakash, Dinesh Elangovan Ramya, Karunakaran Thiyagarajan, Govindhasamy Chinnasamy, Rajasekar Thomas Daniel, Jeyakumar Annadurai, Suresh Arunachalam, Augustine Duraisamy, Kumar Paparaju Ashok, Kumar Rajesh, Dutta Shanta, Toteja Gurudayal S, Gupta Nivedita, Clapham Hannah E, Mehendale Sanjay M, Murhekar Manoj V
Indian Council of Medical Research, National Institute of Epidemiology, Chennai, India.
Indian Council of Medical Research, Regional Medical Research Centre, Northeast Region, Dibrugarh, India.
Lancet Microbe. 2021 Jan;2(1):e41-e47. doi: 10.1016/S2666-5247(20)30175-0.
Since its re-emergence in 2005, chikungunya virus (CHIKV) transmission has been documented in most Indian states. Information is scarce regarding the seroprevalence of CHIKV in India. We aimed to estimate the age-specific seroprevalence, force of infection (FOI), and proportion of the population susceptible to CHIKV infection.
We did a nationally representative, cross-sectional serosurvey, in which we randomly selected individuals in three age groups (5-8, 9-17, and 18-45 years), covering 240 clusters from 60 selected districts of 15 Indian states spread across all five geographical regions of India (north, northeast, east, south, and west). Age was the only inclusion criterion. We tested serum samples for IgG antibodies against CHIKV. We estimated the weighted age-group-specific seroprevalence of CHIKV infection for each region using the design weight (ie, the inverse of the overall probability of selection of state, district, village or ward, census enumeration block, and individual), adjusting for non-response. We constructed catalytic models to estimate the FOI and the proportion of the population susceptible to CHIKV in each region.
From June 19, 2017, to April 12, 2018, we enumerated 117 675 individuals, of whom 77 640 were in the age group of 5-45 years. Of 17 930 randomly selected individuals, 12 300 individuals participated and their samples were used for estimation of CHIKV seroprevalence. The overall prevalence of IgG antibodies against CHIKV in the study population was 18·1% (95% CI 14·2-22·6). The overall seroprevalence was 9·2% (5·4-15·1) among individuals aged 5-8 years, 14·0% (8·8-21·4) among individuals aged 9-17 years, and 21·6% (15·9-28·5) among individuals aged 18-45 years. The seroprevalence was lowest in the northeast region (0·3% [95% CI 0·1-0·8]) and highest in the southern region (43·1% [34·3-52·3]). There was a significant difference in seroprevalence between rural (11·5% [8·8-15·0]) and urban (40·2% [31·7-49·3]) areas (p<0·0001). The seroprevalence did not differ by sex (male 18·8% [95% CI 15·2-23·0] vs female 17·6% [13·2-23·1]; p=0·50). Heterogeneous FOI models suggested that the FOI was higher during 2003-07 in the southern and western region and 2013-17 in the northern region. FOI was lowest in the eastern and northeastern regions. The estimated proportion of the population susceptible to CHIKV in 2017 was lowest in the southern region (56·3%) and highest in the northeastern region (98·0%).
CHIKV transmission was higher in the southern, western, and northern regions of India than in the eastern and northeastern regions. However, a higher proportion of the population susceptible to CHIKV in the eastern and northeastern regions suggests a susceptibility of these regions to outbreaks in the future. Our survey findings will be useful in identifying appropriate target age groups and sites for setting up surveillance and for future CHIKV vaccine trials.
Indian Council of Medical Research.
自2005年基孔肯雅病毒（CHIKV）再次出现以来，印度大多数邦都有该病毒传播的记录。关于印度CHIKV血清阳性率的信息很少。我们旨在估计特定年龄的血清阳性率、感染率（FOI）以及易感染CHIKV的人群比例。
我们进行了一项具有全国代表性的横断面血清学调查，随机选择了三个年龄组（5 - 8岁、9 - 17岁和18 - 45岁）的个体，覆盖了印度15个邦60个选定地区的240个群组，这些地区分布在印度所有五个地理区域（北部、东北部、东部、南部和西部）。年龄是唯一的纳入标准。我们检测血清样本中针对CHIKV的IgG抗体。我们使用设计权重（即邦、区、村或 ward、人口普查枚举区和个体的总体选择概率的倒数）估计每个地区CHIKV感染的加权年龄组特异性血清阳性率，并对无应答情况进行调整。我们构建催化模型来估计每个地区的FOI和易感染CHIKV的人群比例。
从2017年6月19日至2018年4月12日，我们共调查了117675人，其中5 - 45岁年龄组有77640人。在随机选择的17930人中，12300人参与调查，其样本用于估计CHIKV血清阳性率。研究人群中针对CHIKV的IgG抗体总体阳性率为18.1%（95%CI 14.2 - 22.6）。5 - 8岁个体的总体血清阳性率为9.2%（5.4 - 15.1），9 - 17岁个体为14.０%（8.8 - 21.4），18 - 45岁个体为21.6%（15.9 - 28.5）。血清阳性率在东北地区最低（0.3% [95%CI 0.1 - 0.8]），在南部地区最高（43.1% [34.3 - 52.3]）。农村地区（11.5% [8.8 - 15.0]）和城市地区（40.2% [31.7 - 49.3]）的血清阳性率存在显著差异（p<0.0001）。血清阳性率在性别上无差异（男性18.8% [95%CI 15.2 - 23.0] vs女性17.6% [13.2 - 23.1]；p = 0.50）。异质性FOI模型表明，南部和西部地区在2003 - 07年期间感染率较高，北部地区在2013 - 17年期间感染率较高。东部和东北地区的感染率最低。2017年估计的易感染CHIKV的人群比例在南部地区最低（56.3%），在东北地区最高（98.0%）。
印度南部、西部和北部地区的CHIKV传播高于东部和东北地区。然而，东部和东北地区易感染CHIKV的人群比例较高，表明这些地区未来易爆发疫情。我们的调查结果将有助于确定合适的目标年龄组和地点，以建立监测体系和开展未来的CHIKV疫苗试验。
印度医学研究理事会。
