ICMR flags new bacterial threat as Leptospirosis deaths rise in Assam
The disease is transmitted from animals to humans through water, soil, or food contaminated by the urine of infected animals;

Guwahati, July 22: Multiple deaths in Assam since last year have been linked to an underdiagnosed bacterial disease - Leptospirosis, with recent investigations suggesting that the zoonotic menace is expanding its footprint in the Northeast and eastern Himalayas.
A team of experts from the Dibrugarh-based ICMR-Regional Medical Research Centre (RMRC), which investigated an outbreak of fever and jaundice in Goalpara district last year, have confirmed the involvement of ‘Leptospira wolffii’, a strain not previously reported in human infections from Northeast India.
“Our field and laboratory findings revealed coinfection with Hepatitis A virus and Leptospira, with further analysis confirming the involvement of Leptospira wolffii. Over 40 per cent of tested patients were positive for leptospiral antibodies. Many had been using uncovered well water and lived alongside livestock such as pigs and goats, highlighting classic risk factors for zoonotic spread. Tragically, 11 deaths were reported during the outbreak,” said Dr B Borkakoty, Senior Deputy Director, ICMR-RMRC NE.
The findings of the study were published in the ‘Indian Journal of Medical Microbiology’ last week.
Leptospirosis can range in severity from a mild, flu-like illness to a rapidly progressive and potentially fatal disease characterised by systemic inflammatory response syndrome (SIRS) or cytokine storm. Most infections start with symptoms like fever, muscle pain, headache, and vomiting, but in a subset of cases, it can progress to Weil’s disease, which includes jaundice, kidney failure, internal bleeding, and liver dysfunction. A particularly severe complication is pulmonary haemorrhage, which can cause respiratory failure and death within a matter of days. Other complications include meningitis, septic shock, and multi-organ failure. Without early treatment, the fatality rate in severe leptospirosis can exceed 10-20 per cent.
Caused by spiral-shaped bacteria of the genus Leptospira, the disease is typically transmitted from animals to humans through water, soil, or food contaminated by the urine of infected animals.
A fatal case from Sikkim heightened alarm recently. A young adult with no prior health conditions died after rapidly developing severe lung and organ complications. Diagnostic collaboration between STNM, Gangtok and ICMR-RMRC Dibrugarh confirmed Leptospira wolffii as the causative agent, marking the first laboratory-confirmed fatal human case of L. wolffii in the Eastern Himalayas.
The genetic similarity of these strains to those circulating in neighbouring Bangladesh suggests potential cross-border spread of this emerging pathogen. Last month, an outbreak of Leptospirosis was reported from Bhutan with three deaths.
“Number of deaths due to Leptospirosis is not available from Assam as the majority of cases are undiagnosed. But in recent months, multiple deaths in medical colleges have been suspected to be due to Leptospirosis,” Dr Borkakoty told The Assam Tribune.
Fortunately, leptospirosis is treatable if identified early. Mild cases respond well to oral antibiotics like doxycycline or amoxicillin, while severe cases may require intravenous penicillin or ceftriaxone. Critically ill patients often need supportive care, including dialysis and mechanical ventilation. For adults at high risk, such as farmers and flood rescue workers, weekly doxycycline (200 mg) during high-risk seasons has proven effective for prophylaxis. For children and pregnant women, azithromycin is recommended as a safer alternative, typically at age-appropriate doses once weekly during exposure periods.
“The investigations in Assam and Sikkim, led or supported by ICMR-RMRC Dibrugarh, have brought to light a worrisome shift in the regional epidemiology of leptospirosis. These events emphasise the need for improved surveillance, better diagnostic capacity, and integrated “One Health” strategies that consider the interconnectedness of human, animal, and environmental health. Given the ecological vulnerability, frequent flooding, and close human-animal interaction in Northeast India, the risk of further outbreaks is high,” he added.
First formally described by Adolph Weil in Germany in 1886, the disease has long been endemic in tropical and subtropical regions. Recent investigations have now underscored its expanding footprint in India’s Northeast. It is estimated that over one million people are infected each year, with approximately 60,000 deaths worldwide, making it a major zoonotic cause of illness and death.