Outbreak of leptospirosis caused by Leptospira wolffii with HAV coinfections in lower Assam, Northeast India in 2024: Clinical impact and public health implications.

BACKGROUND

In February-March 2024, an outbreak of unknown fever and jaundice with multiple fatalities was reported in Goalpara District, Assam, India. This study aimed to identify the etiological agents responsible for the outbreak to guide public health interventions.

METHODS

Clinical samples from 30 individuals were collected and analyzed using serological and molecular techniques. Serological testing for Hepatitis A Virus (HAV), Hepatitis E Virus (HEV), and Leptospira was performed using IgM ELISA kits. Leptospira DNA was extracted and amplified using PCR targeting the 16S rRNA gene, followed by next-generation sequencing (NGS) for further analysis.

RESULTS

The results revealed HAV IgM antibodies in 23.33 % of cases (7/30), while 40 % (12/30) tested positive for Leptospira-specific IgM by ELISA. Additionally, PCR targeting the 16S rRNA gene confirmed Leptospira DNA in 53.33 % of the urine samples (8/15). Notably, 16.67 % (5/30) of cases exhibited coinfection with both HAV and Leptospira spp., challenging the clinical outcome. Sequencing and phylogenetic analysis of PCR-positive samples identified Leptospira wolffii (L. wolffii) as the causative agent, marking the first report of L. wolffii in human clinical samples from Northeastern India. Recently, L. wolffii, a member of the P2 subclade of Leptospira, has garnered attention due to its pathogenic potential.

CONCLUSION

The findings along with reported fatalities, emphasize the pathogenic potential of L. wolffii and its likely introduction into the region, via cross-border transmission from neighboring Bangladesh, where the strain is prevalent. This study highlights the need for enhanced surveillance and research to monitor emerging Leptospira strains, particularly L. wolffii, in both human and animal populations, to better understand its epidemiology, pathogenicity, and public health implications.