Scrub typhus associated acute kidney injury

Background & objectives: Acute kidney injury associated with scrub typhus is an emerging health problem in the tropics including India. This study intended to find out the incidence, clinical outcome, cytokine response and genotypes of Orientia tsutsugamushi associated with AKI patients in Odisha, a state in eastern India. Methods: Acute febrile illness or history of acute fever with various degrees of kidney involvement admitted to SCB Medical College Hospital, Cuttack were included in the study. A detailed demographic characteristics and clinical features were recorded with pre-tested questionnaire at the time of admission. Scrub Typhus was detected by ‘IgM ELISA’ test (OD > 0.5) and PCR. Routine urine, haematological and biochemical tests were performed. Genotyping of the Orientia tsutsugamushi was done using 56-kDa gene for Orientia species and phylogenetic tree by neighbor-joining method. The plasma level of the IFN-γ (pro-inflammatory cytokine) and IL10 (anti-inflammatory) were measured by commercially available ELISA kit. The statistical analysis was performed using Graph Pad Prism software (version 4). Results: Out of 140 acute febrile illness or history of acute febrile illness patients with AKI admitted to hospital, 32.14% were confirmed to be scrub typhus positive; eschar was seen in 17.8% of them. Of the total scrub typhus positive cases, 24.4% were having multi organ dysfunction. Majority of the AKI patients (60%) were in the “failure” category under RIFLE criteria. The mortality rate was 20.0%. Risk of dialysis requirement and mortality increases with RIFLE classification. “Karp” was the predominant circulating genotype. IFN-γ and IL10 level was high among the scrub typhus associated AKI patients. Interpretation & conclusion: The study shows a high incidence of scrub typhus associated AKI and high case fatality rate. Hence, emphasis should be given on differential diagnosis. RIFLE classification is applicable with increment risk of dialysis requirement and death. An in-depth study is required to determine the role of O. tsutsugamuchi KARP strain and INF-γ/ IL-10 in disease severity so as to identify a prognostic marker.