Clinical, laboratory profile and molecular characterization of among fatal scrub typhus patients from Karnataka, India.

Background: Scrub typhus is a vector-borne infection caused by the obligate intracellular organism In some cases, scrub typhus can result in severe complications, multiorgan failure and death.

Objective: To study the clinical and laboratory profiles of patients who succumbed to scrub typhus.

Methods: A prospective cohort study was conducted from August 2019 through April 2023 on scrub typhus patients admitted to our hospital. Clinical and laboratory parameters of all the patients were recorded, and blood samples were drawn. To confirm scrub typhus, a nested polymerase chain reaction (nPCR) was performed in collected samples. Viable amplicons were sequenced, and phylogenetic analyses were performed to identify infecting genotypes.

Results: A total of 261 patients were enrolled. Of these, nine (3.45%) patients succumbed at a median (Interquartile Range) duration of 5 (1.5, 10.5) days after admission. Sepsis with septic shock (9, 100%) and acute kidney injury (AKI) (6, 66%) were noted among the succumbed patients. All the succumbed patients (100%) required intensive care admission, inotropic and ventilatory support. While 5 (55%) patients required dialysis, two (22%) required blood transfusion. Three (33%) patient samples were co-positive for IgM, and four (44%) patients had superinfection with , multi-drug-resistant (MDR) sepsis, pan drug-resistant (PDR) , and . Phylogenetic analysis revealed Japanese Gilliam-variant (JG-v) like (50%), Karp-like (37.5%), and Japanese Gilliam (JG) like (12.5%) strains among succumbed patients.

Conclusion: Delay in scrub typhus diagnosis can result in severe complications, septic shock, and multisystem organ failure, culminating in death.