Risk Factors and Management Challenges in Developing Countries C
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Leptospirosis: risk factors and management challenges in developing countries C. Goarant To cite this version: C. Goarant. Leptospirosis: risk factors and management challenges in developing countries. Research and Reports in Tropical Medicine, Dove Press, 2016, 2016 (7), pp.29-62. 10.2147/RRTM.S102543. hal-01399806 HAL Id: hal-01399806 https://hal.archives-ouvertes.fr/hal-01399806 Submitted on 8 Jun 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Journal name: Research and Reports in Tropical Medicine Article Designation: Review Year: 2016 Volume: 7 Research and Reports in Tropical Medicine Dovepress Running head verso: Goarant Running head recto: Risk factors and management of leptospirosis open access to scientific and medical research DOI: http://dx.doi.org/10.2147/RRTM.S102543 Open Access Full Text Article REVIEW Leptospirosis: risk factors and management challenges in developing countries Cyrille Goarant Abstract: Leptospirosis is a widespread bacterial zoonosis with highest burden in low-income populations living in tropical and subtropical regions, both in urban and in rural environments. Institut Pasteur International Network, Institut Pasteur in New Rodents are known as the main reservoir animals, but other mammals may also significantly Caledonia, Leptospirosis Research contribute to human infections in some settings. Clinical presentation of leptospirosis is and Expertise Unit, Nouméa, New Caledonia nonspecific and variable, and most of the early signs and symptoms point to the so-called “acute fever of unknown origin”, a major diagnostic challenge in tropical and subtropical areas. However, leptospirosis can rapidly evolve to life-threatening complications, especially if left untreated. There is a need for good awareness of leptospirosis and rapid antibiotic treatment based on clinical and epidemiological suspicion. Severe leptospirosis cases include For personal use only. renal and/or respiratory failure and shock, necessitating intensive care, also seldom available or with limited capacity. Confirmation of leptospirosis relies on biological diagnosis, which unfortunately uses tricky methods seldom available. This biological confirmation, however, is essential for surveillance and public health purpose. A good knowledge of leptospirosis epidemiology (eg, the reservoir animals involved, the Leptospira strains circulating, the sea- sonal and geographical patterns, and specific populations at risk) can be achieved through adequate surveillance and diagnosis. This can pave the way to prevention and intervention strategies and in turn alleviate the toll leptospirosis takes on affected populations. Over the past few years, leptospirosis has been increasingly recognized, as the need for multidisciplinary approaches in a One-Health perspective has been acknowledged, raising hope to successfully tackle the challenges of this zoonosis. Keywords: leptospirosis, epidemiology, public health, treatment, prevention Research and Reports in Tropical Medicine downloaded from https://www.dovepress.com/ by 202.22.228.94 on 29-Sep-2016 Introduction Leptospirosis is a zoonotic bacterial disease with a global distribution. Although its incidence is increasingly recognized in developed high-income countries, the high- est burden is in tropical and subtropical regions worldwide, especially in developing countries.1 The natural history of leptospirosis, sometimes referred to as “leptospirosis Correspondence: Cyrille Goarant cycle”, determines its epidemiology. Pathogenic leptospires are maintained in the renal Institut Pasteur International Network, tubules of chronically infected asymptomatic mammals, mostly, though not exclusively, Institut Pasteur in New Caledonia, rodents.2 Bacteria are then shed through the urine of these animals in the environment, Leptospirosis Research and Expertise Unit, BP61, 98845 Nouméa cedex, where they can survive for weeks to months in shaded, warm, and humid conditions. New Caledonia The conditions allowing the environmental survival of pathogenic leptospires largely Tel +687 27 75 31 Email [email protected] determine the distribution of the disease, but human behavior also plays a role in both submit your manuscript | www.dovepress.com Research and Reports in Tropical Medicine 2016:7 49–62 49 Dovepress © 2016 Goarant. This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms. php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work http://dx.doi.org/10.2147/RRTM.S102543 you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (https://www.dovepress.com/terms.php). Powered by TCPDF (www.tcpdf.org) 1 / 1 Goarant Dovepress direct and indirect exposure. Animals get infected mostly Leptospira: microbiology and through environmental exposure, but venereal transmis- taxonomy sion is also common in some mammal species. Humans Leptospires are thin (~0.1–0.2 µm in diameter and 6–20µm get infected when they come into contact with these motile in length) helicoidal bacteria. The genus Leptospira, within bacteria – through direct contact of skin lesions or mucous Spirochaetes, now includes as many as 22 bacterial species. membranes with the urine of a carrier animal or, more fre- They are clustered in three subgroups (Figure 1) which cor- quently, through contact with freshwater bodies or watered respond to their lifestyle. Saprophytes are normal inhabit- soil contaminated by urine. Human-to-human transmission is ants of freshwater environments. Pathogens are responsible exceptional. Leptospirosis takes a heavy toll in precarious and for the infection of virtually any mammal species, in which farming populations in developing countries from tropical they might cause the disease leptospirosis. Intermediates and subtropical regions worldwide. In humans, leptospirosis are able to infect mammals but usually display a lower viru- first presents as an acute fever with headache and myalgia lence and only cause mild disease. Historically, leptospires and accounts for one of the numerous possible etiologies were mostly classified according to their antigenic patterns of acute fevers in medical settings. If left untreated, it can into serovars (currently more than 250), clustered into more degenerate into severe forms, with kidney and/or liver dam- than 25 serogroups putting together antigenically related age as well as severe pulmonary hemorrhage. Case fatality serovars.3 Unfortunately, the serological taxonomy does not rates range from less than 5% to more than 30% depending correlate with the genetic taxonomy and some serogroups on the clinical presentation and the case management. In include strains from as many as six different bacterial spe- developing countries, leptospirosis poses a number of chal- cies. However, because the epidemiology of leptospirosis lenges not only in the fields of public health (prevention and was long studied with serological tools and because the education, preparedness, intervention) but also in the fields reference serological technique (“A laboratory diagnosis of medical and biological diagnosis and case management. challenge” section) identifies putative serogroups, the For personal use only. L. interrogans L. kirschneri L. noguchii L. santarosai P athogens L. borgpetersenii L. weilii L. alexanderi L. mayottensis L. alstonii L. kmetyi L. licerasiae Inter L. wolffi mediates Research and Reports in Tropical Medicine downloaded from https://www.dovepress.com/ by 202.22.228.94 on 29-Sep-2016 L. fainei L. broomii L. inadai L. terpstrae L. biflexa Saproph L. wolbachii L. vanthielii ytes L. meyeri L. yanagawae L. idonii Leptonema illini 0.01 Figure 1 Molecular phylogeny of the genus Leptospira based on 16S rRNA sequences (neighbor joining method and Kimura’s two-parameter distances). Note: The value 0.01 refers to one substitution per 100 nucleotides. 50 submit your manuscript | www.dovepress.com Research and Reports in Tropical Medicine 2016:7 Dovepress Powered by TCPDF (www.tcpdf.org) 1 / 1 Dovepress Risk factors and management of leptospirosis serological taxonomy is still largely used. Current research of reservoir hosts had not yet been evidenced. This finding notably aims at reconciling historical serology-based epi- might open new fields of research. demiological knowledge with the current genetic taxonomy The animal reservoir in any given environment condi- and molecular epidemiology tools. tions the Leptospira strains involved in human cases. In rural contexts, a variety of Leptospira serovars are maintained and Risk factors of leptospirosis: rural circulated from a number of mammals, including domestic and urban leptospirosis animals like pigs, cattle, dogs, sheep, and goats.