Tickborne Relapsing Fever Caused by Borrelia persica, Uzbekistan and Tajikistan

International audienc

Infection Kinetics and Tropism of Borrelia burgdorferi sensu lato in Mouse After Natural (via Ticks) or Artificial (Needle) Infection Depends on the Bacterial Strain

Borrelia burgdorferi sl is a complex of pathogen bacteria transmitted to the host by Ixodes ticks. European Ixodes ricinus ticks transmit different B. burgdorferi species, pathogenic to human. Bacteria are principally present in unfed tick midgut, then migrate to salivary glands during blood meal and infect a new host via saliva. In this study, efficiency of transmission in a mouse model of three pathogen species belonging to the B. burgdorferi sl complex, B. burgdorferi sensu stricto (B31, N40, and BRE-13), B. afzelii (IBS-5), and B. bavariensis (PBi) is examined in order to evaluate infection risk after tick bite. We compared the dissemination of the Borrelia species in mice after tick bite and needle injection. Location in the ticks and transmission to mice were also determined for the three species by following infection kinetics. After inoculation, we found a significant prevalence in the brain for PBi and BRE-13, in the heart, for PBi, in the skin where B31 was more prevalent than PBi and in the ankle where both B31 and N40 were more present than PBi. After tick bite, statistical analyses showed that BRE-13 was more prevalent than N40 in the brain, in the bladder and in the inguinal lymph node. When Borrelia dissemination was compared after inoculation and tick bite, we observed heart infection only after tick inoculation of BRE-13, and PBi was only detected after tick bite in the skin. For N40, a higher number of positive organs was found after inoculation compared to tick bite. All European B. burgdorferi sl strains studied were detected in female salivary glands before blood meal and infected mice within 24 h of tick bite. Moreover, Borrelia-infected nymphs were able to infect mice as early as 12 h of tick attachment. Our study shows the need to remove ticks as early as possible after attachment. Moreover, Borrelia tropism varied according to the strain as well as between ticks bite and needle inoculation, confirming the association between some strains and clinical manifestation of Lyme borreliosis, as well as the role played by tick saliva in the efficiency of Borrelia infection and dissemination in vertebrates

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

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. 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. 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

Reappraisal of Vipera aspis Venom Neurotoxicity

BACKGROUND: The variation of venom composition with geography is an important aspect of intraspecific variability in the Vipera genus, although causes of this variability remain unclear. The diversity of snake venom is important both for our understanding of venomous snake evolution and for the preparation of relevant antivenoms to treat envenomations. A geographic intraspecific variation in snake venom composition was recently reported for Vipera aspis aspis venom in France. Since 1992, cases of human envenomation after Vipera aspis aspis bites in south-east France involving unexpected neurological signs were regularly reported. The presence of genes encoding PLA(2) neurotoxins in the Vaa snake genome led us to investigate any neurological symptom associated with snake bites in other regions of France and in neighboring countries. In parallel, we used several approaches to characterize the venom PLA(2) composition of the snakes captured in the same areas. [br/] METHODOLOGY/PRINCIPAL FINDINGS: We conducted an epidemiological survey of snake bites in various regions of France. In parallel, we carried out the analysis of the genes and the transcripts encoding venom PLA(2)s. We used SELDI technology to study the diversity of PLA(2) in various venom samples. Neurological signs (mainly cranial nerve disturbances) were reported after snake bites in three regions of France: Languedoc-Roussillon, Midi-Pyrénées and Provence-Alpes-Côte d'Azur. Genomes of Vipera aspis snakes from south-east France were shown to contain ammodytoxin isoforms never described in the genome of Vipera aspis from other French regions. Surprisingly, transcripts encoding venom neurotoxic PLA(2)s were found in snakes of Massif Central region. Accordingly, SELDI analysis of PLA(2) venom composition confirmed the existence of population of neurotoxic Vipera aspis snakes in the west part of the Massif Central mountains. [br/] CONCLUSIONS/SIGNIFICANCE: The association of epidemiological studies to genetic, biochemical and immunochemical analyses of snake venoms allowed a good evaluation of the potential neurotoxicity of snake bites. A correlation was found between the expression of neurological symptoms in humans and the intensity of the cross-reaction of venoms with anti-ammodytoxin antibodies, which is correlated with the level of neurotoxin (vaspin and/or ammodytoxin) expression in the venom. The origin of the two recently identified neurotoxic snake populations is discussed according to venom PLA(2) genome and transcriptome data

Retrospective Study of Lyme Borreliosis Serologies in France: Evolution between 2007 and 2011

International audienceLyme borreliosis is an infectious disease caused by bacteria belonging to the genus Borrelia, transmitted to humans by the bite of infected hard ticks of the genus Ixodes. National surveillance data are very scarce across Europe. Contribution of biology proves essential for diagnosis in the late manifestations. Our aim was to investigate the retrospectively frequency of Lyme positive serologies obtained from two French laboratories, their geographical distribution and their evolution over time. Sera tested were those received at CERBA between January 2007 and December 2011 and Biomnis between 2010 and 2011. IgG and IgM serum isotypes were detected by EIA. Antibodies specificity was analysed by western blot. Between 2010 and 2011, 83 528 patient samples were analyzed and 5 800 patients had positive serology for Lyme disease in France. The standardized rate of positive Lyme serologies (PLS) observed in our study was 4.63 cases per 100,000 person-year in 2010-2011. The regions localized at the center, the East and the NorthEast of France had a high incidence of PLS whatever the year. These areas have a dense forest cover. They represent a favorable habitat for ticks as well as for human outdoor activities. Prevention should be strengthened in these regions particularly in the elderly population. Percentage of positive patients over year was correlated with the annual temperatures, suggesting that climate change may impact Lyme incidence. A strong increase of the incidence was observed between 2010 and 2011 in six regions requiring an enhanced monitoring in the future

Borréliose de Lyme : situation générale et conséquences de l’introduction en Île-de-France d’un nouvel hôte, le tamia de Sibérie

National audienceL’épidémiologie de la borréliose de Lyme demeure encore peu connue en France, les données étant très parcellaires. Les études d’incidence ont mon- tré une grande disparité entre les régions, avec des niveaux de risque éle- vés en Alsace, Lorraine, Limousin, Auvergne et Rhône-Alpes. Les études vectorielles associées montrent des corrélations entre incidences et densi- tés en nymphes infectées, mais les exceptions sont fréquentes. Dans des forêts d’Île-de-France et de Picardie, l’introduction du tamia de Sibérie pourrait intervenir dans la dynamique de la borréliose de Lyme. Cet écureuil semble en effet être réservoir de cette maladie, il porte de fortes charges en Ixodes ricinus et, de plus, il montre une tolérance accrue vis-à-vis des espèces de Borrelia, comparativement aux autres réservoirs. Les recherches en cours visent à préciser le rôle de cet écureuil exotique dans l’incidence de cette maladie en périphérie de la Forêt de Sénart (Essonne) où la popu- lation de tamias est estimée entre 10 000 et 20 000 individus

Is the introduced Siberian chipmunk (<em>Tamias sibiricus</em>) a reservoir host for <em>Borrelia burgdorferi</em> sensu lato in a suburban forests?

National audienc

Genetic structure of marine Borrelia garinii and population admixture with the terrestrial cycle of Lyme borreliosis

Despite the importance of population structure for the epidemiology of pathogenic bacteria, the spatial and ecological heterogeneity of these populations is often poorly characterized. Here, we investigated the genetic diversity and population structure of the Lyme borreliosis (LB) spirochaete Borrelia garinii in its marine cycle involving colonial seabirds and different host races of the seabird tick Ixodes uriae. Multilocus sequence analyses (MLSA) on eight chromosomal and two plasmid loci (ospA and ospC) indicate that B. garinii circulating in the marine system is highly diverse. Microevolution in marine B. garinii seems to be mainly clonal, but recombination and selection do occur. Sequence types were not evenly distributed among geographic regions, with substantial population subdivision between Atlantic and Pacific Ocean basins. However, no geographic structuring was evident within regions. Results of selection analyses and phylogenetic discordance between chromosomal and plasmid loci indicate adaptive evolution is likely occurring in this system, but no pattern of host or vector-associated divergence was found. Recombination analyses showed evidence for population admixture between terrestrial and marine strains, suggesting that LB spirochaetes are exchanged between these enzootic cycles. Importantly, our results highlight the need to explicitly consider the marine system for a complete understanding of the evolutionary ecology and global epidemiology of Lyme borreliosis.Este trabajo ha sido financiado por ‘Institut Polaire-Paul Emile Victor’ (IPEV, programme No. 333), Centre National de la Recherche Scientifique (CNRS – Emerging Infectious Disease Interdisciplinary Program) y la Agence National de la Recherche (ANR-06-JCJC-0095-01). Además también ha recibido financiacion a través de la beca Marie Curie No. PIEF-GA-2008-221243 obtenida por E.Gómez-Díaz.Peer reviewe