First isolation and direct evidence for the existence of large small-mammal reservoirs of Leptospira sp. in Madagascar
2010
Rahelinirina , Soanandrasana (Institut Pasteur de Madagascar(Madagascar). Plaque Unit) | Léon , Albertine (Université de Caen Basse-Normandie(France). IFR 146 ICORE, Frank Duncombe Laboratory) | Harstskeerl , Rudy A. (Food and Agricultural OrganizationKIT Royal Tropical Institute(Italie). WHO/FAO/OIEDepartement KIT Biomedical Research - National Leptospirosis Reference Centre) | Sertour , Natacha (Institut Pasteur(France). National Reference Centre for Borrelia) | Ahmed , Ahmed (Institut Pasteur(France). Epidemiology Unit) | Duplantier , Jean-Marc (INRA , Montferrier Sur Lez (France). UMR 1062 Centre de Biologie et de Gestion des Populations) | Rahalison , Lila (Institut Pasteur de Madagascar(Madagascar). Plaque Unit) | Cornet , Muriel (Institut PasteurCentre Hospitalier Universitaire de Grenoble(France). National Reference Centre for BorreliaParasitology-Mycology Laboratory, University Joseph Fourier)
Background: Leptospirosis has long been a major public health concern in the southwestern Indian Ocean. However, in Madagascar, only a few, old studies have provided indirect serological evidence of the disease in humans or animals. [br/] Methodology/Principal Findings: We conducted a large animal study focusing on small-mammal populations. Five field trapping surveys were carried out at five sites, from April 2008 to August 2009. Captures consisted of Rattus norvegicus (35.8%), R. rattus (35.1%), Mus musculus (20.5%) and Suncus murinus (8.6%). We used microbiological culture, serodiagnosis tests (MAT) and real-time PCR to assess Leptospira infection. Leptospira carriage was detected by PCR in 91 (33.9%) of the 268 small mammals, by MAT in 17 of the 151 (11.3%) animals for which serum samples were available and by culture in 9 of the 268 animals (3.3%). Rates of infection based on positive PCR results were significantly higher in Moramanga (54%), Toliara (48%) and Mahajanga (47.4%) than in Antsiranana (8.5%) and Toamasina (14%) (p = 0.001). The prevalence of Leptospira carriage was significantly higher in R. norvegicus (48.9%), S. murinus (43.5%) and R. rattus (30.8%) than in M. musculus (9.1%) (p < 0.001). The MAT detected antibodies against the serogroups Canicola and Icterohaemorrhagiae. Isolates were characterized by serology, secY sequence-based phylogeny, partial sequencing of rrs, multi-locus VNTR analysis and pulsed field gel electrophoresis. The 10 isolates obtained from nine rats were all identified as species L. interrogans serogroup Canicola serovar Kuwait and all had identical partial rrs and secY sequences. [br/] Conclusions/Significance: We present here the first direct evidence of widespread leptospiral carriage in small mammals in Madagascar. Our results strongly suggest a high level of environmental contamination, consistent with probable transmission of the infection to humans. This first isolation of pathogenic Leptospira strains in this country may significantly improve the detection of specific antibodies in human cases.
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