Rat fever remains Kerala’s biggest killer disease, 391 deaths recorded in 2025

Kannur: Leptospirosis, commonly known as rat fever, has once again emerged as the infectious disease causing the highest number of deaths in Kerala, for the third consecutive year. So far this year, the disease has claimed 391 lives, prompting health experts to warn that its mortality rate of 6.8 per cent must be treated with utmost seriousness. In 2024, the state reported 394 deaths due to the disease. Many patients survive only because specialised treatment is available at hospitals, including medical colleges

Spreading in all seasons

Health officials have observed two major changes in the pattern of the disease over the past four years. Once confined to certain regions, leptospirosis has now spread across the entire state. Previously considered a monsoon-related illness, it has become a year-round disease, occurring in all seasons.

Deaths continue despite availability of treatment

Leptospirosis, which spreads through contact with contaminated water, is both preventable and treatable, with effective medicines readily available. The bacteria responsible for the disease, Leptospira, can be eliminated using antibiotics such as doxycycline and penicillin. Doxycycline can also be used as a preventive measure. PCR tests are available for early diagnosis.

Despite this, fatalities continue to occur, mainly due to delays in diagnosis and treatment. In around 90 per cent of cases, the disease presents mildly and resolves without complications. However, in about 10 per cent of patients it becomes severe, and if complications develop, vital organs such as the liver, kidneys, lungs and heart can be affected.