As a preventive measure to combat menace of rats during the monsoon, Brihanmumbai Municipal Corporation (BMC) has killed more than 40, 000 rats in various wards in Mumbai. Once the monsoon starts, rodent related illnesses like leptospirosis becomes a health issue. It is an infection caused by bacteria called Leptospira. It is spread through rats. So as a precautionary measure, BMC has taken this step to kill around 50000 rats from different wards.