An underestimated, potentially serious infectious disease

Frequently Asked Questions

Is leptospirosis a common disease worldwide, or in Europe more specifically?

One million severe cases are identified worldwide each year, 60,000 of which are fatal(1).
Leptospirosis is re-emerging in Europe and worldwide(2). It is an overlooked, and very probably underestimated, global disease(1).
In the United Kingdom, for example, 2017 saw the highest incidence for 10 years(3,4).
In metropolitan France, the number of cases has doubled in recent years, rising from 300 to more than 600 identified cases annually, i.e. more than one case a day since 2014. In 2014, 628 cases of leptospirosis were identified in mainland France, the highest incidence for 80 years(5).

Is leptospirosis a serious disease?

In most cases, leptospirosis is similar to influenza and can be treated easily. Severe forms of leptospirosis have been observed in some cases, however, and the patient’s health deteriorates, particularly in cases of icterohemorrhagic leptospirosis. Hospitalization is often necessary (88% of serious cases), often in the Intensive Care Unit (64% of serious cases), and the disease can be fatal (10% of serious cases)(6).
Side effects and long-term incapacity can also be observed in 10% and 1.3% of severe cases, respectively(6).

Is icterohemorrhagic leptospirosis common?

The icterohaemorrhagiae serogroup is often the culprit behind cases of human leptospirosis, and is often the cause of the most serious cases worldwide.
In metropolitan France, for example, icterohemorrhagic leptospirosis accounts for a third of identified cases and, in particular, two thirds of serious cases involving hospital admission(7,8).
In the United Kingdom, icterohemorrhagic leptospirosis accounts for approximately half of identified cases(9), and two thirds of identified cases in the Netherlands(10). Elsewhere in the world, Icterohaemorrhagiae accounts for two thirds of the cases in Réunion(11),for example, and half of all cases in French Polynesia(12).

Is leptospirosis a tropical illness?

In tropical countries (the Antilles, for example), the incidence of leptospirosis is 30 times higher than in metropolitan France, where the incidence has doubled since 2014, reaching more than one case a day currently(7).
This re-emergence of leptospirosis is caused by climate change, among other factors(6).
Otherwise, although it was thought that warmer water was more conducive to Leptospira survival, a recent study demonstrated that Leptospira from the Icterohaemorrhagiae serogroup survive, and remain virulent, for up to 10 months, even in water at 4°C(13).

Is leptospirosis primarily associated with leisure activities?

The overall population, exposed to a risk of Leptospira contamination during leisure activities, is indeed larger than the population exposed professionally. It is thus normal that the number of occupational leptospirosis cases is lower than non-occupational cases. The reverse would indicate that the occupational prevention policies implemented had failed.

Leptospirosis is a recognized occupational disease both globally (ILO) and in Europe (Directive 2000/54/EC). In France, for example, epidemiology studies show that a third of all leptospirosis cases, and more than 50% of cases identified in working-age individuals, are of occupational origin, and there have been more than 600 cases of leptospirosis a year since 2014(14,15).

Does leptospirosis only affect sewer workers and those in contact with rats?

Leptospirosis can be transmitted through direct contact with animals, whether dead or alive, via their urine, but most often through indirect contact via the environment: water or mud contaminated with this urine. As Leptospira can survive for up to 14 months at 20°C and 10 months at 4°C, you don’t necessarily have to see an animal to contract leptospirosis. Other than freshwater leisure activities, leptospirosis may be contracted through occupational exposure. These professions include the following:

  • Cleaning and/or maintaining canals, ponds, lakes, rivers, waterways, banks
  • Activities related to fish farming
  • Working in sewers, treatment plants
  • Some freshwater activities: professional anglers and divers, water bailiffs
  • Some activities specific to the overseas departments and territories

What responsibilities do employers have to employees exposed to leptospirosis in France?

Employers should ensure that the health of employees or agents is protected. By law, employers have a duty of care(16). To achieve this, based on the advice of occupational health professionals, the employer should, in particular, fund the protective methods recommended by the High Council of Public Health (Opinion of 18 March 2005). These recommendations include:

  • information for employees on the risk of leptospirosis
  • implementing hygiene rules and collective means of prevention (waste management, combatting rodent proliferation, etc.)
  • implementing individual protective measures (wearing protective equipment, vaccinating those who are particularly exposed if necessary).

Are employees at risk of leptospirosis covered by an enhanced medical monitoring scheme to prevent occupational leptospirosis?

The application decrees of the new labor law, which appeared in late 2016, outline the medical monitoring for professionals exposed to group II biological agents, such as leptospirosis(17).
By law, these workers should have an initial appointment, called an Information and Prevention Visit (IPV), with an occupational health professional before starting the job.
Periodic monitoring appointments with the occupational physician are recommended, and should be performed every five years at most. This schedule may be adapted to requirements, however, and the appointment schedule may be increased (for example, to facilitate proper application of a vaccination schedule).

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(1) L. Filleul et al. ; Santé Publique France – La leptospirose dans les régions et départements français d’outre-mer; Bulletin Epidémiologique Hebdomadaire ; n°8-9 ;4 avril 2017
(2) Hartskeerl et al, Emergence, control and re-emerging leptospirosis: dynamics of infection in the changing world, 2011, Clinical Microbiology and Infection, vol 17: 494-501
(3) M. Picardeau, Rapport annuel d’activité du CNRL 2016
(4) JM. Estavoyer, « Leptospirose en Franche-Comté : données cliniques, biologiques et thérapeutiques. Médecine et maladies infectieuses »; Septembre 2013: pages 379-385
(5) S.Tubiana, «Risk Factors and Predictors of Severe Leptospirosis in New Caledonia» PLoS Negl Trop Dis. 2013 Jan; 7(1): e1991.
(6) P. Hochedez, «Factors Associated with Severe Leptospirosis», Martinique 2010–2013», Emerg Infect Dis. 2015 Dec; 21(12): 2221–2224.
(7) G. André-Fontaine, «Waterborne Leptospirosis: Survival and Preservation of the Virulence of Pathogenic Leptospira spp. in Fresh Water. »Curr Microbiol. 2015 Jul;71(1):136-42
(8) Baranton G, Postic D Centre National de Référence des leptospires, Institut Pasteur Paris,  Synthèse La leptospirose en France de 2001 à 2003 : 1-8
(9) Watrin M. Étude descriptive des cas de leptospirose diagnostiqués en Normandie sur la période 2010-2014. Saint-Maurice : Institut de veille sanitaire ; 2016: 1-28.
(10) Décret n° 2009-1194, Journal Officiel du 07/10/2009 (Code de la Sécurité Sociale)
(11) Décret n° 2007-1121 du 19/07/2007 (Code de la Sécurité Sociale)
(12) Cass.Soc. 30.11.2010: n°08-70390
(13) Décret n° 2016-1908 du 27 décembre 2016 relatif à la modernisation de la médecine du travail