Leptospirosis

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Leptospirosis
The leptospirosis are infectious diseases.

History
Sickness described by Weil in 1886: a form of jaundice flamboyant loud. In retrospect, one can think of an infection Icterohemorragie serogroup, which gives serious forms and complete information of the disease.

Epidemiology
Ubiquitaire on the planet, leptospirosis is over-represented in the Indian Ocean region. A first case in Gabon was published in 1994. This disease seems much more prevalent than diagnosed. The incidence in France is 0.53 cas/100 000 inhabitants. Aquitaine, the Ile-de-France and Poitou-Charentes are over-represented (50% of cases). The incidence is much higher in the overseas departments and territories (French overseas departments and territories attached to France): 12.5 / 100000 inhabitants in the case of La Reunion, and, respectively, 9.12 and 13 with regard to French Guiana, Martinique and Guadeloupe. New Caledonia accuses an incidence of 150/100 000 inhabitants, and Polynesia, 40/100 000 inhabitants. A study of Mexican séroprevalence conducted among blood donors in 1995 showed an incidence of 7% (antibody positive). People with the disease are at 80% of young men. The disease does not usually expresses among women, and even less in children. Women are as much in touch with this bacterium (according to a study conducted seroprevalence Reunion in 1987) than men. Children are less often diagnosed or infected for reasons poorly understood. One hypothesis that the author makes is that the severity of the clinical picture is directly related to muscle mass of patients. In that immuno-infectious disease, there are antibodies muscles responsible for rhabdomyolysis, which is itself the source of kidney failure. It is therefore not surprising that men are over-represented in the population of patients hospitalized for leptospirosis.

Vectors
The Leptospira can be transported by various means of delivery, including by rodents; among them, rats play an important role in the transmission of the disease. All animals can be vectors (including dogs). Generally, the wild animals are healthy carriers (which are, however, a multiplication of bacteria in the kidneys), while the disease becomes manifest in domestic animals.

The infection can be caused by the bite of an infected animal, or through contact with an infected animal, with its urine or with his dead tissue. In most cases, the infection is by penetration of bacteria through a wound or even minimal skin, and mucous membranes in contact with water infected urine vector or his corpse. Some populations are most at risk (breeders, farmers, veterinarians, sewer, as well as professionals and followers of aquatic recreation).

The transmission among humans is rare, breast milk can carry the infectious agent to contaminate a child. Contamination intrauterine fetus is possible and often lethal.

Geographic Distribution
Anthropozoonose présente partout dans le monde. toutefois elle est plus fréquente en zone tropicale, les bactéries survivant plus longtemps dans l'eau douce tiède. Le département de La Réunion compte une incidence trente fois plus élevée que la France métropolitaine.

Pathophysiology
Transmission is in most cases in an indirect way by infected water or by contact with infected animal tissues (work in slaughterhouses). It has long spoken of active penetration of the bacteria through the skin. The leptospires can also enter the human body by mucous membranes.

The transmission can also be direct (bite).

Agent Pathogen
The pathogen responsible for leptospirosis is the Leptospira interrogans (bacteria in the range of Spirochætales as tréponème pale pathogen of syphilis). The genus Leptospira measure 6 to 12 micrometers. The bacterium is spiral, flexible, mobile, with the ends in a hook and périplasmatique flagellum. There are many serovars (icterohaemorragiae, canicola, pomona, for example) that do not require a signature antigenic homogeneous, which makes it difficult to design effective vaccines.

Signs functional
Leptospirosis is manifested in various forms, which make it difficult to diagnose because it can be cofondue with a strong influence (high fever and aches). It may begin with pain diffuse or localized (eg pain Meningeal) that if they are not diagnosed in time lead to a wandering of speech and reasoning (because of the high rate of uremia that develops in the Blocking blood by the kidneys.

Incubation
7 to 14 days (range 2 to 21 days)
First phase clinical
Often brutal beginning with a high fever (92%), headache (75%), myalgia (71%) preferentially bearing on the thighs and calves, reproducible to the pressure of muscles. Cough, hemoptysis, chest pain can complete the picture.

Sometimes, only a fever is present (24% of cases still in a series of interest) exam: conjunctival bleeding, jaundice, herpes labialis, sthétacoustiques signs of pneumonia, rash, maculopapular siégreant macular or on the trunk. Splénomegalie, hepatomégalie and lymph nodes can supplement the table.

Second phase clinical
In the first phase followed by a remission of 2 to 3 days. Then signs of the first phase reappear sometimes supplemented by signs of meningeal irritation and even encephalitis or meningeal franc.

Tables bleeding more or less hidden (purpura, epistaxis, hemoptysis, hematemesis) secondary to thrombocytopenia, which is itself derived from the appearance of antibodies platelets. Biologically, this corresponds to the onset of damage viscerales The cardiac frequent, as evidenced by myocarditis and / or pericarditis.

Clinic in children
Clinical rare and unusual. It has been observed: high blood pressure, cholecystite alithiasique, pancreatitis, after scaling rash, gangrene and cardio respiratory arrest. The most frequent rest meningeal irritation feverish.

Consideration complementary
The standard bacteriological examinations (direct examination and culture) are possible but reserved for specialized laboratories because it requires very special circumstances to be profitable. We use blood or CSF as a levy in the first week and then the urine in the second week. In clinical practice routine diagnosis therefore relies on serology. Two serological tests are used in testing (ELISA test and macroagglutination). If positivity of one of these two tests must confirm the result by the reference technique: the test of Martin and Pettit. There is also a test in PCR.

Prevention
There is a vaccine spirolept, but it only protects against serotype ictero-haemorragiae (representing approximately 45% of leptospirosis). However, the different serotypes share common antigens, and we can ask the question of a partial immunity from the vaccine against the other serotypes. Moreover, the century Icterohemmoragiae who is responsible for the most serious form of leptopsirose called "disease Weil" The rest of the prevention rests on the fight against exposure at both professional and recreational level (boots, gloves), deratting outside the rainy period (at the risk of seeing an increase in cases by "scrubbing" of corpses by rainwater, by vaccination of pets, in the fight against stray dogs.