Division of Epidemiology & Biostatistics, ICMR-National AIDS Research Institute, Pune, Maharashtra, India.
Division of Microbiology, ICMR-National AIDS Research Institute, Pune, Maharashtra, India.
Indian J Med Res. 2020 Apr;151(4):350-360. doi: 10.4103/ijmr.IJMR_1330_18.
BACKGROUND & OBJECTIVES: In India, acute encephalitis syndrome (AES) cases are frequently reported from Gorakhpur district in Uttar Pradesh. Scrub typhus is one of the predominant aetiological agents for these cases. In order to delineate the extent of the background of scrub typhus seroprevalence and the associated risk factors at community level, serosurveys during both lean and epidemic periods (phase 1 and phase 2, respectively) of AES outbreaks were conducted in this region.
Two community-based serosurveys were conducted during lean (April-May 2016) and epidemic AES (October-November 2016) periods. A total of 1085 and 906 individuals were enrolled during lean and epidemic AES periods, respectively, from different villages reporting recent AES cases. Scrub typhus-seronegative individuals (n=254) during the lean period were tested again during the epidemic period to estimate the incidence of scrub typhus.
The seroprevalence of Orientia tsutsugamushi during AES epidemic period [immunoglobulin (Ig) IgG: 70.8%, IgM: 4.4%] was high as compared to that of lean AES period (IgG: 50.6%, P <0.001; IgM: 3.4%). The factors independently associated with O. tsutsugamushi positivity during lean AES period were female gender, illiteracy, not wearing footwear, not taking bath after work whereas increasing age, close contact with animals, source of drinking water and open-air defecation emerged as additional risk factors during the epidemic AES season. IgM positivity was significantly higher among febrile individuals compared to those without fever (7.7 vs. 3.5%, P=0.006). The seroincidence for O. tsutsugamushi was 19.7 per cent, and the subclinical infection rate was 54 per cent.
INTERPRETATION & CONCLUSIONS: The community-based surveys identified endemicity of O. tsutsugamushi and the associated risk factors in Gorakhpur region. The findings will be helpful for planning appropriate interventional strategies to control scrub typhus.
在印度，急性脑炎综合征（AES）病例经常在北方邦戈勒克布尔区报告。丛林斑疹伤寒是这些病例的主要病因之一。为了描绘丛林斑疹伤寒血清流行率的背景程度和社区层面的相关危险因素，在 AES 暴发的淡季（第 1 阶段）和流行期（第 2 阶段）分别在该地区进行了两次基于社区的血清学调查。
在淡季（2016 年 4 月至 5 月）和 AES 流行期（2016 年 10 月至 11 月）进行了两次基于社区的血清学调查。在淡季和流行期 AES 期间，分别从报告近期 AES 病例的不同村庄招募了 1085 名和 906 名个体。在淡季期间的丛林斑疹伤寒血清阴性个体（n=254）在流行期再次进行检测，以估计丛林斑疹伤寒的发病率。
在 AES 流行期间，恙虫病东方体（O. tsutsugamushi）的血清流行率[免疫球蛋白（Ig）IgG：70.8%，IgM：4.4%]高于淡季 AES 期间（IgG：50.6%，P<0.001；IgM：3.4%）。在淡季 AES 期间，与 O. tsutsugamushi 阳性相关的独立因素为女性、文盲、不穿鞋、工作后不洗澡，而在流行期 AES 季节，年龄增长、与动物密切接触、饮用水源和露天排便成为额外的危险因素。与无发热者相比，发热个体的 IgM 阳性率明显更高（7.7%比 3.5%，P=0.006）。O. tsutsugamushi 的血清发病率为 19.7%，亚临床感染率为 54%。
基于社区的调查确定了戈勒克布尔地区恙虫病东方体的流行程度和相关危险因素。这些发现将有助于规划适当的干预策略来控制丛林斑疹伤寒。
