Revista Cubana de Medicina Tropical
On-line version ISSN 1561-3054
Rev Cubana Med Trop vol.54 no.1 Ciudad de la Habana Jan.-Apr. 2002
Ecole Nationale Veterinaire, france
Epidemiology of leptospirosis
DeCS: LEPTOSPIROSIS/epidemiología; INCIDENCIA; LEPTOSPIRA.
Subject headings: LEPTOSPIROSIS/epidemiology; INCIDENCE; LEPTOSPIRA.
Leptospirosis is noticed everywhere in the world but with higher incidence in tropical countries as latin America, India, south eastern Asia but even in temperate areas as European Union or Japan, with a lesser extend.
Mortality rate is around 10 p.cent of the patients but may reach 23.6 in some countries as Barbados, a Caribean island (table 1).
TABLE 1. Leptospirosis incidence (WHO-1999, 74, 237-44)
Leptospirosis Worldwide WHO * / 100 000
But what means « leptospirosis » ?
Leptospirosis is induced by pathogenic Spirochaetales, belonging to the genus Leptospira.
Now this genus is divided in several genomospecies : at least 7 for the pathogenic strains. But up to now, for experimental diagnosis and epidemiological studies, the serological classification was still used. This type of classification is based on agglutinating antibodies produced by animals infected by this bacteria. So the genus Leptospira was divided in 2 species, the saprophytic one L. biflexa s.l. and the pathogenic L. interrogans s.l. The basic taxon is the serovar. Because of close antigenic communities, several serovars are gathered in a serogroup (Usually, names of serovars and serogroups are written in roman but for the serogroup, the first letter is a capital).
Each of the strains of L. interrogans s.l could induce leptospirosis.
Leptospires in contaminated material may infect a man or another Mammal. Penetrating in the blood vessels, they multiply and reach several organs: lung, liver and kidney or reach the cerebrospinal fluid. It is the onset of the infection and /or disease. Acute disease may be observed in several species, especially in man and dog. Hepatitis with a severe jaundice is often related to acute leptospirosis, as renal failure or pulmonary hemorrhages. But in other species as cattle, pig, horse, subacute or even chronical leptospirosis is generally observed. For these animals reproduction failure are the most frequent. Infection induces antibody production by the animals, which help to their recovery (and are used for serological diagnosis). But many of these animals remain renal carriers, shedding leptospires in their urine several weeks or months after the infection.1-25
So, man and domestic animals are the major species involved in leptospirosis but the most powerfull animals are the reservoirs, which are wild animals and belong generally to the Rodents group. We performed a study on trapped animals in metropolitean Francia and in Guadeloupe.
We studied first the seroprevalence in Myocastor coypu, Ondatra zybethicus, Rattus norvegicus, Rattus rattus, and other small rodents, Oryctolagus cuniculus and the mangooses (Herpetesicus javanicus) trapped in Guadeloupe.
Seroprevalence is around 48 % in the myocastors (737 animals trapped), 34 to 50% in the rats (357 R. norvegicus and 409 R. rattus ) and 47 % in the mangooses, indicating that many wild animals are infected by leptospires as they secreted agglutinating antibodies. But, to be a reservoir with a strong role in the transmission of the pathogenic strains, a wild species has to shed leptospires, i.e. to be a renal carrier.
So we attempted to isolate leptospires from the kidney of some trapped animals of each species (table 2).
TABLE 2. Carriage status of several species trapped in metropolitean France and Guadeloupe
|R.rattus *|| |
IH - Bal
Aus - Sej
|H.javanica *|| |
IH Sej - Aus
* results in Guadeloupe
IH= Icterohaemorrhagiae, Sej= Sejroë, Bal= Ballum, Aus= Australis.
It is often said that one species of mammal is a shedder for one serogroup of leptospires. We see in table 2 that several strains belonging to several serogroups were isolated from a one species. While often serologically positive in our sample, the rabbits were not identified as renal carriers.
These animals are not sick of leptospirosis, they shed leptospires in their urine and if the urine contaminates fresh water, slightly alcalin, pathogenic leptospires can remain infectious in the swamps, pounds and rivers.
Domestic animals, as man, are more often contaminated by soiled waters than by the direct contact with the wild animals. The higher is the renal carriage, the lower is the susceptibility to a clinical disease (fig. 1).
So people are at risk in several circumstances (fig. 2):
Fig. 2. People at risk.
Leptospirosis is an occupationnal risk for rice growing, fishing, harvesting, but even during animal breeding and slaughter .
Leptospirosis is a leisure risk for water activities as swimming, fihing, hunting, boating
Leptospirosis is too a home risk by rodents and in a lesser extend by dog.
The epidemiological conditions of leptospire transmission could be modified by excess of rain falls, huricanes (Mitch, El Nino), by increasing and/or changes in Rodents populations.
The importation of a new species in one country could modify the risks: for example the american coypu is widely developped in France, mangooses were imported in Caribean Island.
Man could be more exposed to leptospire transmission by modifying its one occupational and leisure activities.
- Ellis WA. Leptospirosis: a review of veterinary aspects. Irish Vet News 1990;12:6-12.
- Faine S, Adler B, Bolin C, Perolat P. Leptospira and leptospirosis. MediSci , Melbourne:Medi Sci; 1999.
- Baril C, Saint Girons I. Sizing of the Leptospira genome by pulse-field agarose gel electrophoresis. FEMS Microbiol Letters 1990; 71:95-100.
- Brendle JJ, Rogul M, Alexander AD. Deoxyribonucleic acid hybridization among selected leptospiral serotypes. Int J Sys ac 1974;24:205-14.
- Hovind HK. Leptospiraceae, a new family to include Leptospira Noguchi 1917 and Leptonema, gen.nov.. Int J Sys Bac 1979;29:245-51.
- Ramadass PS, Meerarani MD, Venkatesha MD, Senthilkumar A, Nachimuthu K. Characterization of leptospiral serovars by randomly amplified polymorphic DNA fingerprinting. Int J Sys Bac 47:575-86.
- SaintGirons I, Norris SJ, Gobel J, Meyer J, Walker EM, Zuerner R. Genome structure of spirochetes. Res Microbiol 1992;143:615-21.
- Yasuda PH, Steigerwalt AG, Sulzer KR, Kaufmann AF, Rogers F, Brenner DJ. Deoxyribonucleic acid relatedness between serogroups and serovars in the family Leptospiraceae with proposals for seven new Leptospira species. Int J Sys Bac 1987;37:407-15.
- Adamus C, Buggin-Daubié M, Izembart A, Sonrier C, Guigand L, Tasson MT, André-Fontaine G, Wyers M. Chronic hepatitis associated with leptospiral infection in vaccinated Beagles. J Comp Pathol 1997; 117:311-28.
- Alves VA, Gayotto LC, Brito T, Santos RT, Wakamatsu A, Vianna MR, Sakata E. Leptospiral antigens in the liver of experimentally infected Guinea pig and their relation to the morphogenesis of liver damage. Exp Tox Pathology 1992;44:425-34.
- Bolin C, Cassells JA. Isolation of Leptospira interrogans serovar bratislava from stillborn and weak pigs in Iowa. JAVMA 1990;196:1601-04.
- Chu K, Rathinam P, Namperumalsamy P, Dean D. Identification of Leptospira species in the pathogenesis of uveitis and determination of clinical ocular characteristics in south India. J Infect Dis 1998;177:1314-21.
- Edwards CN, Nicholson GD, Everard COR. Thrombocytopenia in leptospirosis. Am J Trop Med Hyg 1982;31:827-9
- Higgins RJ, Harbourne JF, Little TWA. Mastitis and abortion in dairy cattle associated with Leptospira of the serotype hardjo. Vet Rec 1980;107:307-10.
- Parma AE, Cerone SI, Sansinea SA. Biochemical analysis by SDS-PAGE and westen blotting of the antigenic relationship between Leptospira and equine ocular tissues. Vet Immunol Immunopath 1992;33:179-85.
- André-Fontaine G, Peslerbe X, Ganière JP. Occupational hazard of unnoticed leptospirosis in water ways maintenance staff : Eur J Epidemiol 1992;8:228-32.
- André-Fontaine G, Boudet R, Coquet J de, Reynal PH, Ganière JP, Larrat M. Contamination humaine et animale par Leptospira interrogans australis. Méd Mal Infect 1992;22:880-2.
- Anonymous outbreak of leptospirosis among white-water rafters-Costa-Rica, 1996.MMWR 1997;46:577-9
- Baker MF, Baker HJ. Pathogenic Leptospira in Malaysian surface waters. I.A method of survey for Leptospira in natural waters and soils. Am J Trop Med Hyg 1970;19:485-92.
- Feresu S, Bolin C, Korver H. A new leptospiral serovar, ngavi, in the Tarassovi serogroup isolated from Zimbabwe oxen. Int J Sys Bact 1998;48:207-13.
- Kuiken T, van Dijk JE, Terpstra WJ, Bokhout BA. The role of the common vole (Microtus arvalis) in the epidemiology of bovine infection with Leptospira interrogans serovar hardjo. 28:353-61.
- Levett PN, Walton D, Waterman LD, Whittington CU, Mathison GE, Edwards COR. Surveillance of leptospiral carriage by feral rats in Barbados. West Indian Med J 1998;47:15-17
- Michel V, Ruvoen-Clouet N, Menard A, Sonrier C, Fillonneau C, Rakotovao F, et al. Role of the coypu (Myocastor coypus)in the epidemiology of leptospirosis in domestic animals and humans in France. Eur J Epidemiol 2001;17:111-21.
- Waitkins S, Wanyangu AS, Palmer M. The coypu as a redent reservoir of leptospira infection in Great Britain. J Hyg 1985;95:409-17.
- Wolff JW . Historical review. The possible pathogenicity of water leptospires (L.biflexa) 1920-1930. Tropic Geograph Med 1978;30:175-82.
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