An underestimated, potentially serious infectious disease

How is it contracted?

Leptospirosis is contracted when thin, mobile bacteria called “Leptospira” get into your body. This can happen if you are in contact with animals (living or dead) who carry the disease, or in a humid environment contaminated with their urine (fresh water, mud). Leptospira can enter the body through wounds, scratches, mucosa (ocular, oral, nasal, etc.) and even through healthy macerated skin.

leptospirosis contamination scheme

Weil’s Disease

Leptospirosis is a zoonosis carried by animals. Several mammals can transmit this disease, such as: wild animals (rats, coypu, etc.), livestock (porcine, ovine and bovine), domestic animals (dogs, horses, etc.) Leptospirosis is often called “Weil’s disease”, and rodents, including rats, are the primary carriers of icterohemorrhagic leptospirosis.

They are healthy carriers. In the host organism, Leptospira multiply and propagate, via the blood, to various organs such as the liver, lungs and kidneys. The bacteria in the kidneys are expelled into the natural environment through urine, thus contaminating the streams and soil.

Leptospira: a hardy bacteria in humid environments, even at 4°C

Depending on the environment, Leptospira survive for a longer or shorter time. These bacteria can survive for more than six months in urine-saturated, soil but barely a day in seawater. Leptospira fear saltwater, and leptospirosis is a freshwater disease(1).
An in-vitro laboratory study performed recently demonstrated that Leptospira Icterohaemorrhagiae can survive, and remain pathogenic, for a year in fresh water at 20°C and for 10 months at 4°C(2).
Accordingly, although leptospirosis is known as a tropical illness, the bacteria that cause this infection can survive, and remain virulent, even in cold water.


Infectious disease veterinarian, specialist in infectious zoonoses

A diagnostically-challenging disease

After an incubation phase ranging from seven to 12 days or even a month, leptospirosis manifests as influenza-like symptoms (fever with chills, muscle pain, headaches, frequent gastrointestinal disorders), suggesting several illnesses(3). Leptospirosis is thus difficult to diagnose.

Serious cases quickly develop into potentially fatal multiple-organ failure, characterized by kidney failure, visceral hemorrhage and jaundice, all of which may require hospitalization and possibly intensive care(4,5).

This is why it’s important to research patients’ engagement in high-risk activities, with the aim of guiding the diagnosis as quickly as possible, and offering effective treatment before the symptoms worsen. When identified early, the disease can be treated with antibiotics. Serious cases require specific treatment, depending on the organs affected by the leptospirosis (dialysis, for example).

Recherche et prévention autour de la Leptospirose - Imaxio

(1) Ferguson IR. A european Perspective on Leptospirosis. Microbiology Europe 1994 ; janv-fév : 8-11
(2) 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
(3) Adler B. (Ed) Leptospira and Leptospirosis, Current Topics in Microbiology and Immunology  Sringer-Verlag Berlin Heidelberg 2015; 387: 1-293. DOI 10.1007/978-3-662-45059-8
(4) L. Filleul et al. ; Santé Publique France – La leptospirose dans les régions et départements français d’outre-mer ; Bulletin Epidémiologique Hebdomadaire ; 4 avril 2017 ; numéro 8-9
(5) 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