Leptospirosis – emerging public health problem 557 J. Biosci. 33(4), November 2008 1. Introduction Leptospirosis has been recognized as an important emerging global public health problem because of its epidemic proportions and increasing incidence in both developing and developed countries (Meites et al 2004). It is an acute bacterial infection caused by spirochetes, with different pathogenic species of the genus Leptospira (Waitkins 1987). Leptospirosis has wide geographical distribution and occurs in tropical, subtropical and temperate zones. In the developed world, the incidence of the disease has come down substantially and most cases that occur now are associated with recreational exposure to the contaminated water. Contrastingly, the incidence appears to be increasing in developing countries (Tangkanakul et al 2000). Most countries in the South East Asia region are endemic to leptospirosis. On an average 10,000 severe cases requiring hospitalization occur world over annually (Faine 1994). Several outbreaks of leptospirosis have been reported in the past few years in various places viz., Nicaragua (Zaki and Sheih 1996), Salvador (Ko et al 1999) and Rio de Janeiro (Barcellos and Sabroza 2001) in Brazil and Orissa (Faine http://www.ias.ac.in/jbiosci J. Biosci. 33(4), November 2008, 557–569, © Indian Academy of Sciences 557 Keywords. Genome; leptospirosis; occupational risk; public health problem; Weil’s disease; zoonosis Abbreviations used: CFR, case fatality ratio; MPT, microagglutination test; OMP, outer-membrane proteins; PCR, polymerase chain reactions Leptospirosis: an emerging global public health problem P VIJAYACHARI*, A P SUGUNAN and A N SHRIRAM Regional Medical Research Centre (Indian Council of Medical Research), WHO Collaborating Centre for Diagnosis, Research, Reference and Training in Leptospirosis, Port Blair 744 101, Andaman and Nicobar Islands, India *Corresponding author (Fax, 91-3192-251163; Email, pblicmr@sancharnet.in) Leptospirosis has been recognized as an emerging global public health problem because of its increasing incidence in both developing and developed countries. A number of leptospirosis outbreaks have occurred in the past few years in various places such as Nicaragua, Brazil and India. Some of these resulted due to natural calamities such as cyclone and floods. It is a direct zoonotic disease caused by spirochetes belonging to different pathogenic species of the genus Leptospira. Large number of animals acts as carriers or vectors. Human infection results from accidental contact with carrier animals or environment contaminated with leptospires. The primary source of leptospires is the excretor animal, from whose renal tubules leptospires are excreted into the environment with the animal urine. Majority of leptospiral infections are either sub clinical or result in very mild illness and recover without any complications. However, a small proportion develops various complications due to involvement of multiple organ systems. In such patients, the clinical presentation depends upon the predominant organs involved and the case fatality ratio could be about 40% or more. Febrile illness with icterus, splenomegaly and nephritis (known as Weil’s disease), acute febrile illness with severe muscle pain, febrile illness with pulmonary haemorrhages in the form of haemoptysis, jaundice with pulmonary haemorrhages, jaundice with heamaturea, meningitis with haemorrhages including sub conjunctival haemorrhage or febrile illness with cardiac arrhythmias with or without haemorrhages are some of the syndromes. Because of the protean manifestations of leptospirosis it is often misdiagnosed and under-reported. Although the basic principles of prevention such as source reduction, environmental sanitation, more hygienic work-related and personal practices etc., are same everywhere, there is no universal control method applicable to all epidemiological settings. Comprehensive understanding of the eco- epidemiological and cultural characteristics of a community that faces the problem of leptospirosis is an essential prerequisite for evolving an effective and acceptable control measure. [Vijayachari P, Sugunan A P and Shriram A N 2008 Leptospirosis: an emerging global public health problem; J. Biosci. 33 557–569]