First Isolation and Direct Evidence for the Existence of Large Small-Mammal Reservoirs of Leptospira sp. in Madagascar

Abstract

BackgroundLeptospirosis 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.Methodology/Principal FindingsWe 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.Conclusions/SignificanceWe 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.

Cross-Sectional Study of Leptospira Seroprevalence in Humans, Rats, Mice, and Dogs in a Main Tropical Sea-Port City

“…[28][29][30] Our Leptospira isolation rates from R. rattus, R. norvegicus, and M. musculus kidney samples of 6.3% (1 of 16), 0.0% (0 of 4), and 0.0% (0 of 49) were therefore similar to the 3.2% (3 of 94), 6.3% (6 of 86), and 0.0% (0 of 55) obtained from these three species in Madagascar, respectively. 31 We also confirmed that the infection of the black rat with L. interrogans serovar Icterohaemorrhagiae/Copenhageni could not be differentiated using PFGE as previously shown. 32 This I15 isolate is now the first isolate to be included in a Colombian MAT diagnostic panel.…”

Leptospira spp. Prevalence in Small Mammal Populations in Cotonou, Benin

“…Nevertheless, it should be noted that most of the related serovars within L. interrogans, L. kirschneri, and L. borgpetersenii originate or have been found in Africa or nearby islands (Gem, Kuwait, Kibos, Kambale, Ndambari, and Kamituga) and/or have a worldwide distribution (Icterohaemorrhagiae, Pomona, and Grippotyphosa) and, hence, support that the observations are consistent with the current knowledge on serovars circulating in this continent [35,36].…”

Similarities in Leptospira Serogroup and Species Distribution in Animals and Humans in the Indian Ocean Island of Mayotte

“…Other studies reported a low genetic diversity among locally circulating Leptospira strains within the rat population. [27][28][29][30][31][32] Here, we showed that rats in Mayotte carried four genomospecies (Table 4) and that the genetic diversity among Leptospira strains infecting black rats is unique. Rattus sp.…”

“…Rattus sp. is considered as the preferred reservoir host for L. interrogans and L. borgpetersenii [28][29][30][32][33][34] and to our knowledge L. kirschneri (serovar Bim) has only been isolated from rats in Barbados. 35 Our serological results corroborate serological observations and molecular data on human strains and confirmed that field strains from serogroup Icterohaemorrhagiae are absent on Mayotte.…”