Deciphering the genotypic diversity and epidemiology of scrub typhus genotypes in India: A systematic review and...

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 I² 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.