Leptospirosis: A Disease of the Rural Fields and Urban Slums – A Comprehensive Review

Abstract Leptospirosis is a globally important zoonotic disease caused by pathogenic spirochetes of the genus Leptospira . First identified by Adolf Weil in 1886 and later named Leptospira interrogans , the disease persists in reservoir hosts, especially rodents, and is transmitted to humans through contact with contaminated water or soil. The bacteria flourish in warm, alkaline freshwater, leading to seasonal outbreaks linked to flooding, agricultural work, and recreational water activities. Clinically, leptospirosis presents with a broad spectrum of manifestations, ranging from mild febrile illness to severe forms such as Weil’s disease, characterized by jaundice, renal failure, and pulmonary hemorrhage. Pathogenesis involves bacteremia, immune activation that often culminates in a cytokine storm, and direct tissue damage, particularly in the liver, kidneys, and lungs. Diagnosis remains difficult and depends on using both molecular methods, like polymerase chain reaction, during early infection and serological tests such as the microscopic agglutination test in later stages. Despite advances in genomic classification and increasing awareness of its burden, especially in endemic regions like India, leptospirosis is often underdiagnosed because of nonspecific symptoms and limited laboratory resources. Better surveillance, quick diagnosis, and public health measures are essential to reduce its illness and death.