Why is leptospirosis claiming so many lives in Kerala? Premium

Leptospirosis outbreak in Kerala raises concerns about over-reliance on doxycycline, highlighting need for better prevention strategies.

For a disease that has displayed a consistent pattern and mortality profile over decades, leptospirosis has been claiming an unusually high number of lives in Kerala in recent years.

In the past two years alone, leptospirosis emerged as the infectious disease that killed the maximum number of people, with the proportion of mortality going up every year. This has led many public health experts to now wonder if the State has been a little too complacent in its “over dependence” on the broad-spectrum antibiotic doxycycline as the one-shot strategy to prevent and manage leptospirosis to the exclusion of all other possible strategies, including better epidemiological research and improved risk communication to people.

Leptospirosis is a tropical zoonotic disease, highly integrated with an environment in which both humans and animals thrive. The Leptospira bacterium that causes leptospirosis spreads through the urine of infected livestock, pets, rodents and wild animals. The bacteria can persist for several weeks to months in contaminated soil and enter human bodies through minor cuts or abrasions on the skin or even through sodden skin.

The profile of those who are affected by the disease has remained more or less the same: most are farmers or manual/agricultural labourers or people whose work puts them at risk of regular contact with water/soil that may be contaminated. M. Abraham Ittyachen, professor of medicine, MOSC Medical College, Kolenchery, who has been treating leptospirosis for the past two decades, says that in Central Kerala, cases usually spike during the pineapple harvest season. “Plantation workers go into the pineapple fields early in the morning. They wear gum boots, but the skin on their hands, which are unprotected, sustain micro tears from the serrated leaf edges. The dew on the leaves, is often contaminated by rodents in the farm.”

However, this picture is changing in recent times, with even urban residents contracting the disease.

Leptospirosis cases are reported throughout the year in Kerala. Cases generally spike during the monsoon season and then start to dip as the dry season begins.

Yet this year, in just the first two months, the Integrated Disease Surveillance Programme has reported 567 cases and 37 deaths (including confirmed and probable cases) due to leptospirosis. In 2024, the State had the largest number of leptospirosis cases at 5,999 and 386 deaths. It was no different in 2023, when there were 5,186 cases and 282 deaths, meaning that leptospirosis mortality spiked by 36.8% just between 2023 and 2024.