Spotted fever group rickettsioses in suspected AFI patients: 18-year spatio-temporal analysis from Southern India

This retrospective spatio-temporal analysis drew on an 18-year dataset of patients with suspected acute febrile illness (AFI) evaluated for spotted fever group rickettsiae (SFGR). The investigators framed spotted fever as a vector-borne disease transmitted primarily by infected tick bites, and sought to describe case distribution and its correlation with seasonality.

Patients were classified as spotted fever positive if either serology (ELISA or IFA) or a molecular assay (Nested PCR or qPCR) returned a positive result. Demographic data from confirmed cases were then compiled for analysis. A total of 2153 suspected AFI patients were tested over the study period, of whom 516 (24%) met criteria for spotted fever.

Spatial analysis showed marked geographic clustering: Vellore district accounted for 39.9% of cases, Chittoor for 38.8%, Tirupattur for 12.5%, Ranipet for 4.5%, and Tiruvannamalai for 4.3%. Temporally, the greatest burden of cases occurred between September and March, with a distinct peak in January. Children younger than 10 years and housewives were identified as the populations at greatest risk.

The abstract does not report treatment regimens, case-fatality outcomes, coinfection rates, or comparisons against other rickettsial or non-rickettsial causes of AFI, so inferences about management are not supported by the data presented. As a retrospective descriptive analysis, the work is subject to selection and misclassification bias, and causal interpretation of the observed spatial and seasonal patterns is limited.

For clinicians working in or receiving referrals from the implicated districts, the findings reinforce the value of maintaining a high index of suspicion for SFGR in undifferentiated febrile illness, particularly in young children presenting during or following the monsoon season.