KOCHI: Deaths from leptospirosis, or rat fever, have soared tenfold over the last decade. Over the same period, the fatality rate climbed from 2.6% to 6%, the highest for a bacterial infection.
Leptospirosis has claimed 200 lives in the state this year as of November 26. The record for the most fatalities from the disease is 229 in 2007. According to the Directorate of Health Services (DHS), the state has seen an additional 2,442 suspected cases and 158 suspected deaths this year.
The pathogen is transmitted through contact with contaminated water or urine of infected animals and risk often increases following a storm or flood. However, the death toll remained low even after the major floods of 2018 and 2019.
In 2024, the number of people infected with leptospirosis crossed 3,000, against over 19,500 reported dengue cases. However, the higher fatality rate make leptospirosis far more deadlier than dengue (0.3%). Health experts say that cases of leptospirosis could even be missed during fever season or a dengue epidemic. As a result, the actual infection and death figures could be higher.
Conducive weather, characterised by intermittent rain, has helped in the proliferation of leptospira species, they say. Besides, lack of awareness has contributed to the spike in fatality rates. “Earlier, most of the patients used to be field workers. Now, cases are more widespread,” said Dr Althaf A, epidemiologist and professor at Thiruvananthapuram Government Medical College Hospital. The disease has been detected even among bedridden patients who have minimal contact with the outside environment, he said.
“Infections now tend to worsen rapidly and lead to increased fatality. There is a need to investigate the rise in leptospirosis cases and their transmission routes,” Dr Althaf added.
The bacteria have a greater probability of coming into contact with people if they can endure longer in the surroundings. Shortcomings in waste management and intermittent rains that keep the pathogens alive are considered to be the major factors behind the spurt. “Leptospira has now become ubiquitous, significantly increasing the risk of infection.
The number of carriers, particularly rodents, has risen, and studies have shown that serovars (distinct variation within a species of bacteria) once thought to be harmless can now cause the disease,” said Dr S Nandakumar, assistant director of the animal husbandry department.
Many cases can go unnoticed because of lack of significant clinical indicators. The infection can range from a mild flu-like illness to life-threatening multiorgan failure and death.
