National Institute of Virology Kerala Unit, Government T.D. Medical College Hospital, Alappuzha, India.
Viral Diagnostic Laboratory, National Institute of Virology, Pune, India.
Indian J Med Res. 2017 Jul;146(Supplement):S70-S75. doi: 10.4103/ijmr.IJMR_1638_15.
BACKGROUND & OBJECTIVES: Several outbreaks of acute encephalitis syndrome (AES) have been reported in Alappuzha district, Kerala State, India, in the past. The aetiology of these outbreaks was either inconclusive or concluded as probable Japanese encephalitis virus (JEV) infection based on clinical presentation. The role of West Nile virus (WNV) in AES outbreaks was also determined. However, the extent of WNV infection has not been studied in this region previously. A population-based cross-sectional serosurvey study was undertaken to determine the seroprevalence of JEV and WNV in Alappuzha district.
A total of 30 clusters were identified from 12 blocks and five municipalities as per the probability proportional to size sampling method. A total of 1125 samples were collected from all age groups. A microneutralization assay was performed to estimate the prevalence of JEV and WNV neutralizing antibodies in the sample population.
Of 1125 serum samples tested, 235 [21.5%, 95% confidence interval (CI): 15.2-27.8%] and 179 (15.9%, 95% CI: 9.6-22.3%) were positive for neutralizing antibodies against WNV and JEV, respectively. In addition, 411 (34.5%, 95% CI: 26.7-42.2%) were positive for cross-reactive antibodies against flaviviruses.
INTERPRETATION & CONCLUSIONS: The study showed the seroprevalence of WNV and JEV antibodies in the surveyed area and the WNV seroprevalence was greater than JEV. It is necessary to create awareness in public and adopt suitable policy to control these diseases.
过去，印度喀拉拉邦阿拉普扎县曾多次报告急性脑炎综合征（AES）暴发。这些暴发的病因要么不确定，要么根据临床表现推断为可能的日本脑炎病毒（JEV）感染。西尼罗河病毒（WNV）在 AES 暴发中的作用也已确定。然而，此前该地区尚未研究 WNV 的感染程度。进行了一项基于人群的横断面血清学调查研究，以确定阿拉普扎县 JEV 和 WNV 的血清流行率。
根据概率比例大小抽样法，从 12 个街区和 5 个直辖市中确定了 30 个集群。从所有年龄组共采集了 1125 个样本。采用微量中和试验估计样本人群中 JEV 和 WNV 中和抗体的流行率。
在检测的 1125 份血清样本中，分别有 235 份（21.5%，95%置信区间[CI]：15.2-27.8%）和 179 份（15.9%，95%CI：9.6-22.3%）对 WNV 和 JEV 具有中和抗体。此外，411 份（34.5%，95%CI：26.7-42.2%）对黄病毒交叉反应抗体呈阳性。
该研究显示了调查区域中 WNV 和 JEV 抗体的血清流行率，且 WNV 的血清流行率高于 JEV。有必要在公众中提高认识并采取适当的政策来控制这些疾病。
