Department of Infectious Diseases, Christian Medical College, Vellore 632004, Tamil Nadu, India.
Department of Infectious Diseases, Christian Medical College, Vellore 632004, Tamil Nadu, India.
Int J Infect Dis. 2018 Jun;71:53-55. doi: 10.1016/j.ijid.2018.03.018. Epub 2018 Apr 10.
The serological detection of IgM antibodies is the most widely used test to diagnose scrub typhus infection. However, the kinetics of IgM and IgG antibodies post-infection remain elusive, which could contribute to false positivity. The objective of this study was to document the nature of the evolution of these antibody titres after infection.
Adult patients previously confirmed to have scrub typhus by IgM ELISA, positive PCR, or both, were included in this cross-sectional study. The levels of IgM and IgG antibodies in serum samples were tested using an ELISA and the distribution curve was plotted.
Two hundred and three patients were included in this study. Post-infection serum sampling was done between 1 month and 46 months after documented infection. IgM levels declined gradually but remained elevated above the diagnostic cut-off for up to 12 months post-infection. However, IgG levels continued to rise reaching a peak at 10 months, followed by a gradual decline over several months. In the majority of cases, the IgG levels remained above the cut-off threshold for more than 36 months.
Clinicians need to be cautious in using a single serum sample for the detection of IgM to diagnose scrub typhus, as it remains elevated for up to 12 months after the infection, whereas the serum IgG level could be used as an indicator of past infection.
血清 IgM 抗体检测是诊断恙虫病感染最常用的方法。然而，感染后 IgM 和 IgG 抗体的动力学仍不清楚，这可能导致假阳性。本研究的目的是记录感染后这些抗体滴度的变化规律。
本横断面研究纳入了先前通过 IgM ELISA、PCR 阳性或两者均阳性确诊为恙虫病的成年患者。使用 ELISA 检测血清样本中 IgM 和 IgG 抗体的水平，并绘制分布曲线。
本研究共纳入 203 例患者。在有记录的感染后 1 个月至 46 个月进行了感染后血清采样。IgM 水平逐渐下降，但在感染后 12 个月内仍高于诊断临界值。然而，IgG 水平持续升高，在 10 个月时达到峰值，随后数月逐渐下降。在大多数情况下，IgG 水平在 36 个月以上仍高于临界值。
临床医生需要谨慎使用单次血清样本检测 IgM 来诊断恙虫病，因为 IgM 在感染后长达 12 个月内仍处于升高状态，而血清 IgG 水平可作为既往感染的指标。
