Guwahati: A mysterious fever outbreak in Assam’s Goalpara district has led to the detection of a rare and emerging zoonotic infection—Leptospira wolffii—in human samples for the first time in Northeast India.
The outbreak, which occurred between February and March 2024, also involved co-infections with the Hepatitis A virus (HAV), complicating clinical outcomes and resulting in multiple fatalities.
A team of researchers from the ICMR-Regional Medical Research Centre, Dibrugarh, and collaborating institutions conducted the investigation after a sudden outbreak of unknown fever and jaundice in five villages of Goalpara, located roughly 130 km west of Guwahati.
According to a new study published in the International Journal of Medical Microbiology, the outbreak involved “an unknown fever with jaundice-like symptoms and reported fatalities” across the five villages. Laboratory investigations revealed that 40% of the tested individuals were positive for Leptospira-specific IgM antibodies, while 23.33% tested positive for HAV. Notably, 16.67% of the cases showed co-infection with both pathogens, making diagnosis and treatment particularly challenging.
Clinical samples from 30 individuals were analyzed using a combination of serological tests and molecular diagnostics, including next-generation sequencing.
“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,” the study notes.
Leptospirosis, caused by Leptospira spp., infects over a million people globally and accounts for approximately 60,000 deaths annually. It is a waterborne disease prevalent in tropical and subtropical regions, typically transmitted through contact with urine of infected animals or contaminated environments.
The disease can manifest with a wide range of symptoms, from mild to severe, including fever, jaundice, myalgia, headache, anorexia, cough, and abdominal pain.
Leptospira wolffii, a member of the P2 subclade of Leptospira, is increasingly gaining attention for its emerging role in human disease. The bacterium had not previously been reported in human clinical samples in Northeast India. It belongs to a group of spirochetes that thrive in waterlogged or unsanitary environments and spread via the urine of infected animals, contaminating local water sources.
The study, based on 41 cases—including 11 deaths—reported that patients presented with fever, jaundice, headache, myalgia, and nausea. “Among the symptomatic cases, 45% were positive for Leptospira IgM ELISA,” the study stated, with PCR and next-generation sequencing confirming the presence of L. wolffii DNA in urine samples.
Health authorities were advised to initiate control measures. As part of the immediate response, “residents of the affected villages were advised to use safe drinking water and recommended to take prophylactic antibiotic therapy, preferably doxycycline (200 mg weekly).”
The researchers stressed the need for enhanced surveillance and monitoring of emerging Leptospira strains in both human and animal populations. “This study highlights the need to better understand its epidemiology, pathogenicity, and public health implications,” the report concludes.
The outbreak underscores the vulnerability of flood-prone regions like Goalpara to waterborne and zoonotic diseases, particularly in the context of poor sanitation and close human-animal interactions. With climate variability and cross-border transmission playing increasing roles in disease dynamics, experts emphasize that proactive detection and response systems are critical.
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