Leptospirosis epidemiology and demographics

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Venkata Sivakrishna Kumar Pulivarthi M.B.B.S [2]


Leptospirosis occurs worldwide but is most common in temperate or tropical climates. It is an occupational hazard for many people who work outdoors or with animals, for example, farmers, sewer workers, veterinarians, fish workers, dairy farmers, or military personnel. It is a recreational hazard for campers or those who participate in outdoor sports in contaminated areas and has been associated with swimming, wading and whitewater rafting in contaminated lakes and rivers. The incidence is also increasing among urban children. Epidemiology of human leptospirosis is complex and dynamic due to the interaction of pathogen, host, animal reservoir and environment. With the increase in urban population, occupational and recreational exposure to surface water and climatic changes results in increase in prevalence of leptospirosis recently.

Epidemiology and Demographics

Leptospirosis caused by pathogenic Leptospira species have been found worldwide, except in Antarctica. It is most common in warm, humid environments and in the areas with a high disease incidence in humans include the Caribbean and Latin America, Oceania and parts of Asia. During the past few decades, leptospirosis has become seriously neglected, especially in countries of temperate regions.
The main reasons for this situation are probably:

  • A relatively less number of cases noted in the temperate climate zone
  • Well established, quite effective methods of therapy and prevention of the disease
  • Seemingly well-determined epidemiologic situation concerning the disease.[1]


Leptospirosis, is a zoonotic emerging infectious disease with a worldwide distribution.[2] Tropical climatic conditions are most favourable for survival of leptospires and the morbidity is high due to extreme weather events such as cyclones and floods occurring in recent years.[3][4] Leptospirosis is particularly prevalent in wet tropical and subtropical regions as the pathogenic leptospires can survive longer in a warm and humid environment.


Leptospirosis is an increasing public health problem worldwide, evidenced by markedly increasing incidence rates and multiple outbreaks allover the world. Even though multiple outbreaks has been reported, the true spread and incidence of leptospirosis remains unknown, as the availability of diagnostic tests, testing facilities and surveillance systems are highly variable and frequently absent. Incidence rate in temperate climate is in a range of ~0.1–1 per 100000 per year and it is ~10–100 per 100 000 in the humid tropical regions. In high-exposure risk groups and during outbreaks, the incidence may be >100 per 100000.[5]

Case Fatality Rate

Higher morbidity due to leptospirosis is observed in regions with higher proportion of surface fresh waters such as lakes, rivers, developed canal systems.[6][7] Case fatality rate due to leptospirosis is > 10%, and > 500,000 cases of severe leptospirosis are reported each year. Worldwide case fatality rates range from 3%-50%.[8]


Leptospirosis has no age predilection, but more sever form of the disease is common in the age group of ≤ 5 years or ≥ 65 years.[9]


Leptospirosis has no gender predilection usually, but due to high occupational exposure in men lead to high risk of disease incidence in male than female.[10]

Developed Countries

Leptospirosis is a zoonotic disease with global distribution, commonly occurs in tropical and subtropical regions. In United States most reported cases are seen in Hawaii.[11]

Water born outbreaks in United States
Place of outbreak Number of cases reported
Philadelphia, 1939 7
Georgia, 1940 35
Wyoming, 1942 24
Alabama, 1950 50
Georgia, 1952 26
South Dakota, 1956 3
Florida, 1958 9
Iowa, 1959 40
Washington, 1964 61
Tennessee, 1975 7
Missouri, 1985 4
Kauai, Hawaii, 1987 8
Illinois, 1991 5
Kauai, Hawaii, 1992 8
Illinois & Wisconsin,1998 74

Developing Countries

Leptospirosis is a neglected disease with a greatest burden on impoverished populations from developing countries and tropical regions.[12] Most of the tropical regions are developing countries and there is higher risk of exposure to the human population from the infected animals such as livestock, domestic pets, wild or feral animals. It is a major public health problem in many developing countries, such as Latin America and South-East Asia where the climate is more favorable for leptospires.[13] 90% of deaths due to leptospirosis occur due to pulmonary hemorrhage and acute renal failure.[14]


  1. Hartskeerl RA, Collares-Pereira M, Ellis WA (2011). "Emergence, control and re-emerging leptospirosis: dynamics of infection in the changing world". Clin Microbiol Infect. 17 (4): 494–501. doi:10.1111/j.1469-0691.2011.03474.x. PMID 21414083.
  2. Levett PN (2001). "Leptospirosis". Clin Microbiol Rev. 14 (2): 296–326. doi:10.1128/CMR.14.2.296-326.2001. PMC 88975. PMID 11292640.
  3. Lau CL, Smythe LD, Craig SB, Weinstein P (2010). "Climate change, flooding, urbanisation and leptospirosis: fuelling the fire?". Trans R Soc Trop Med Hyg. 104 (10): 631–8. doi:10.1016/j.trstmh.2010.07.002. PMID 20813388.
  4. Vijayachari P, Sugunan AP, Shriram AN (2008). "Leptospirosis: an emerging global public health problem". J Biosci. 33 (4): 557–69. PMID 19208981.
  5. LastName, FirstName (2003). Human leptospirosis : guidance for diagnosis, surveillance and control. Geneva: World Health Organization. ISBN 9241545895.
  6. Jansen A, Schöneberg I, Frank C, Alpers K, Schneider T, Stark K (2005). "Leptospirosis in Germany, 1962-2003". Emerg Infect Dis. 11 (7): 1048–54. doi:10.3201/eid1107.041172. PMC 3371786. PMID 16022779.
  7. Baranton G, Postic D (2006). "Trends in leptospirosis epidemiology in France. Sixty-six years of passive serological surveillance from 1920 to 2003". Int J Infect Dis. 10 (2): 162–70. doi:10.1016/j.ijid.2005.02.010. PMID 16298537.
  8. Abela-Ridder, Bernadette; Sikkema, Reina; Hartskeerl, Rudy A. (2010). "Estimating the burden of human leptospirosis". International Journal of Antimicrobial Agents. 36: S5–S7. doi:10.1016/j.ijantimicag.2010.06.012. ISSN 0924-8579.
  9. Forbes AE, Zochowski WJ, Dubrey SW, Sivaprakasam V (2012). "Leptospirosis and Weil's disease in the UK". QJM. 105 (12): 1151–62. doi:10.1093/qjmed/hcs145. PMID 22843698.
  10. prasad, jagadeesh. "Leptospirosis" (PDF).
  11. Centers for Disease Control and Prevention (CDC) (1994). "National notifiable diseases reporting--United States, 1994". MMWR Morb Mortal Wkly Rep. 43 (43): 800–1. PMID 7935317.
  12. McBride AJ, Athanazio DA, Reis MG, Ko AI (2005). "Leptospirosis". Curr Opin Infect Dis. 18 (5): 376–86. PMID 16148523.
  13. Picardeau, M. (2013). "Diagnosis and epidemiology of leptospirosis". Médecine et Maladies Infectieuses. 43 (1): 1–9. doi:10.1016/j.medmal.2012.11.005. ISSN 0399-077X.
  14. prasad, jagadeesh. "Leptospirosis" (PDF).