Nema Ram Kumar, Singh Ashutosh Kumar, Raj Dharma, Gupta Priyal, Tiwari Rajnarayan R, Purwar Shashank
Department of Microbiology, All India Institute of Medical Sciences, Bhopal, India.
Division of Environmental Biotechnology Genetics and Molecular Biology, ICMR - National Institute for Research in Environmental Health, Bhopal, 462 030, India.
Microb Pathog. 2025 Feb;199:107182. doi: 10.1016/j.micpath.2024.107182. Epub 2024 Dec 6.
Scrub typhus is a significant cause of Acute Febrile Illness in India and presents a range of clinical manifestations influenced by the genotypes of the causative agent, Orientia tsutsugamushi. Understanding the distribution of these genotypes is crucial for public health planning, diagnostic accuracy, and vaccine development.
In this systematic review, we analyzed 18 studies from an initial pool of 2013 records identified through database searches following PRISMA guidelines. The relevance of the findings to the genotype prevalence of Scrub typhus in India was taken into consideration throughout the selection process. Various genotyping methods, predominantly Polymerase Chain Reaction (PCR), were used in these studies to identify genotypes such as Karp, Gilliam, Kato, and others.
The review revealed diverse prevalence rates of Scrub typhus genotypes across different Indian states. The Karp genotype is the most prevalent in India, with a pooled prevalence of 47 %, followed by the Kato genotype at 40 % and the Gilliam genotype at 28 %. The Karp genotype showed significant variability, with prevalence rates ranging from 100 % in Andhra Pradesh (2018) to 6.16 % in Uttar Pradesh (2016-2017). The Kato genotype's presence varied significantly, with high prevalence in certain states like Karnataka and absence in others like Andhra Pradesh. The Gilliam genotype also displayed a unique distribution pattern, dominating in Uttar Pradesh with a prevalence of 93.8 % in some years. Other genotypes like Boryong, IHS-II, Neimeng, Kuroki, TA763, and Kawasaki also showed varied prevalence across states. There was significant heterogeneity in the prevalence rates of different genotypes among studies, as indicated by I statistics.
The diversity in Scrub typhus genotypes across India underscores the disease's complex epidemiology, presenting diagnostic challenges and opportunities for targeted public health interventions. For efficient disease management and control plans in India, it is imperative to understand the changing genetic landscape of scrub typhus through ongoing study and surveillance.
恙虫病是印度急性发热性疾病的一个重要病因，其临床表现受病原体恙虫病东方体基因型的影响。了解这些基因型的分布对于公共卫生规划、诊断准确性和疫苗开发至关重要。
在本系统评价中，我们按照PRISMA指南，通过数据库检索从最初的2013条记录中分析了18项研究。在整个筛选过程中，均考虑了研究结果与印度恙虫病基因型流行率的相关性。这些研究主要采用各种基因分型方法，以聚合酶链反应（PCR）为主，来鉴定诸如Karp、Gilliam、Kato等基因型。
该评价揭示了印度不同邦恙虫病基因型的不同流行率。Karp基因型在印度最为常见，合并流行率为47%，其次是Kato基因型，为40%，Gilliam基因型为28%。Karp基因型表现出显著的变异性，流行率范围从安得拉邦（2018年）的100%到北方邦（2016 - 2017年）的6.16%。Kato基因型的存在差异显著，在某些邦如卡纳塔克邦流行率较高，而在其他邦如安得拉邦则不存在。Gilliam基因型也呈现出独特的分布模式，在北方邦占主导地位，某些年份的流行率达93.8%。其他基因型如Boryong、IHS - II、Neimeng、Kuroki、TA763和Kawasaki在各邦的流行率也各不相同。I统计量表明，不同研究中不同基因型的流行率存在显著异质性。
印度恙虫病基因型的多样性凸显了该疾病复杂的流行病学特征，带来了诊断挑战，也为有针对性的公共卫生干预提供了机遇。对于印度有效的疾病管理和控制计划而言，通过持续的研究和监测来了解恙虫病不断变化的遗传格局至关重要。
