Usha K, Kumar E, Kalawat Usha, Kumar B Siddhartha, Chaudhury A, Gopal D V R Sai
Department of Virology, Sri Venkateswara University, Tirupati, India.
Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Tirupati, India.
Indian J Med Res. 2016 Oct;144(4):597-603. doi: 10.4103/0971-5916.200886.
BACKGROUND & OBJECTIVES: Scrub typhus is a vector-borne zoonotic infection caused by Orientiatsutsugamushi. Local epidemiology of the circulating serotypes of scrub typhus is not available from most parts of India. We conducted this study for the diagnosis of scrub typhus using IgM ELISA and to detect O. tsutsugamushi serotypes circulating in southern Andhra Pradesh, India.
Samples were collected from patients clinically suspected to have scrub typhus and were subjected to IgM ELISA to measure IgM antibodies against O. tsutsugamushi. Nested polymerase chain reaction (PCR) was performed targeting strain-specific regions in ELISA-positive samples.
Of a total of 663 samples, 258 (38.91%) were found to be positive by IgM ELISA. Serotypes could be detected in 230 (34.69%) samples only. Only two serotypes, Karp and Kawasaki, were found in the serum samples, with the former being predominant. The dual infection of Karp and Kawasaki serotypes was found in seven patients. Other serotypes such as Gilliam, Kuroki and Kato were not detected in the samples.
INTERPRETATION & CONCLUSION: The nested PCR products proved useful in presumptively identifying the endemic O. tsutsugamushi serotypes. The present study could be significant in understanding scrub typhus epidemiology in this region.
恙虫病是由恙虫东方体引起的一种媒介传播的人畜共患感染病。印度大部分地区缺乏恙虫病流行血清型的当地流行病学资料。我们开展本研究，旨在采用IgM酶联免疫吸附测定（ELISA）诊断恙虫病，并检测在印度安得拉邦南部流行的恙虫东方体血清型。
从临床疑似恙虫病的患者中采集样本，进行IgM ELISA检测以测定抗恙虫东方体的IgM抗体。对ELISA阳性样本进行巢式聚合酶链反应（PCR），扩增菌株特异性区域。
在总共663份样本中，258份（38.91%）经IgM ELISA检测呈阳性。仅在230份（34.69%）样本中检测到血清型。血清样本中仅发现两种血清型，即Karp型和Kawasaki型，前者占主导。7例患者发现Karp型和Kawasaki型双重感染。样本中未检测到其他血清型，如Gilliam型、Kuroki型和Kato型。
巢式PCR产物有助于初步鉴定地方性恙虫东方体血清型。本研究对于了解该地区恙虫病流行病学具有重要意义。
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