Emerging Dual infection: A retrospective study on Scrub typhus and Leptospirosis Prevalence and Co-infection in the hilly region of Himachal Pradesh in North India.

BACKGROUND

OBJECTIVES

Scrub typhus and Leptospirosis are emerging zoonotic bacterial infections prevalent in the Himalayan region, including Himachal Pradesh in India. Scrub typhus and leptospirosis are key drivers of acute febrile illness, particularly in tropical and subtropical regions. Both diseases share overlapping clinical symptoms and making differential diagnosis challenging in endemic region. The aim of present study was to investigate the seroprevalence of scrub typhus and leptospirosis and their co-infection in patients with acute febrile illness (AFI) in the hilly area of Himachal Pradesh, focusing on demographic and seasonal trends.

METHODS

This retrospective hospital-based study was conducted for a period of one year, from January 2023 to December 2023 at Viral Research and Diagnostic Laboratory (VRDL), in the Department of Microbiology at Dr. Rajendra Prasad Government Medical College Tanda, Himachal Pradesh, a tertiary care hospital in northern India. Blood samples were collected from both in and out patients presenting with acute febrile illness. Total 1538 samples were tested for Scrub typhus and 860 samples were tested for Leptospirosis by Enzyme Linked Immunosorbent assay (ELISA).

RESULTS

During the study period, the seroprevalence of scrub typhus was 12.40%, while leptospirosis had a slightly higher prevalence of 14.65%. The co-infection rate of scrub typhus and leptospirosis was 2.4% in patients with acute febrile illness. Seroprevalence of scrub typhus was more in female population whereas leptospirosis showed a male predominance. Age-wise distribution revealed that both diseases were most prevalent among individuals age group of 21-40 years, followed by the 41-60 age group. Co-infection of both scrub typhus and leptospirosis was observed in 37 patients, with 14 were males and 23 were females, indicating a higher occurrence of co-infection in the latter. A seasonal variation highlights that the majority of scrub typhus cases occur during the month of August, September and October while leptospirosis cases peaks in the month of September and October.

INTERPRETATION

CONCLUSION

The findings of this study highlighted the critical importance of strengthening awareness, improving early diagnostic efforts, and ensuring prompt interventions-particularly during the seasonal peaks. Special attention should be given to cases involving co-infection, as they pose greater challenges in clinical management.