Leptospirosis is a zoonotic disease caused by Leptospira interrogans bacteria, infecting over 500,000 humans annually worldwide with fatality rates up to 25%. It is more common in warm, wet climates and spreads between animals and humans. Animal reservoirs include rats, mice, dogs, and domesticated animals. High-risk human groups include those exposed to animals or contaminated water through occupation or behaviors. Further research is needed to fully understand transmission dynamics and identify all reservoirs to help control spread.