[Show abstract][Hide abstract]ABSTRACT: Background:
The recent geographical expansion of phlebotomine vectors of Leishmania infantum in the Mediterranean subregion has been attributed to ongoing climate changes. At these latitudes, the activity of sand flies is typically seasonal; because seasonal phenomena are also sensitive to general variations in climate, current phenological data sets can provide a baseline for continuing investigations on sand fly population dynamics that may impact on future scenarios of leishmaniasis transmission. With this aim, in 2011-2013 a consortium of partners from eight Mediterranean countries carried out entomological investigations in sites where L. infantum transmission was recently reported.
A common protocol for sand fly collection included monthly captures by CDC light traps, complemented by sticky traps in most of the sites. Collections were replicated for more than one season in order to reduce the effects of local weather events. In each site, the trapping effort was left unchanged throughout the survey to legitimate inter-seasonal comparisons. Data from 99,000 collected specimens were analyzed, resulting in the description of seasonal dynamics of 56,000 sand flies belonging to L. infantum vector species throughout a wide geographical area, namely P. perniciosus (Portugal, Spain and Italy), P. ariasi (France), P. neglectus (Greece), P. tobbi (Cyprus and Turkey), P. balcanicus and P. kandelakii (Georgia). Time of sand fly appearance/disappearance in collections differed between sites, and seasonal densities showed variations in each site. Significant correlations were found between latitude/mean annual temperature of sites and i) the first month of sand fly appearance, that ranged from early April to the first half of June; ii) the type of density trend, varying from a single peak in July/August to multiple peaks increasing in magnitude from May through September. A 3-modal trend, recorded for P. tobbi in Cyprus, represents a novel finding for a L. infantum vector. Adults ended the activity starting from mid September through November, without significant correlation with latitude/mean annual temperature of sites. The period of potential exposure to L.infantum in the Mediterranean subregion, as inferred by adult densities calculated from 3 years, 37 sites and 6 competent vector species, was associated to a regular bell-shaped density curve having a wide peak center encompassing the July-September period, and falling between early May to late October for more than 99% of values. Apparently no risk for leishmaniasis transmission took place from December through March in the years considered. We found a common pattern of nocturnal females activity, whose density peaked between 11 pm and 2 am.
Despite annual variations, multiple collections performed over consecutive years provided homogeneous patterns of the potential behavior of leishmaniasis vectors in selected sites, which we propose may represent sentinel areas for future monitoring. In the investigated years, higher potential risk for L. infantum transmission in the Mediterranean was identified in the June-October period (97% relative vector density), however such risk was not equally distributed throughout the region, since density waves of adults occurred earlier and were more frequent in southern territories.
[Show abstract][Hide abstract]ABSTRACT: In the south of France, Leishmania infantum is responsible for numerous cases of canine leishmaniasis (CanL), sporadic cases of human visceral leishmaniasis (VL) and rare cases of cutaneous and muco-cutaneous leishmaniasis (CL and MCL, respectively). Several endemic areas have been clearly identified in the south of France including the Pyrénées-Orientales, Cévennes (CE), Provence (P), Alpes-Maritimes (AM) and Corsica (CO). Within these endemic areas, the two cities of Nice (AM) and Marseille (P), which are located 150 km apart, and their surroundings, concentrate the greatest number of French autochthonous leishmaniasis cases. In this study, 270 L. infantum isolates from an extended time period (1978-2011) from four endemic areas, AM, P, CE and CO, were assessed using Multi-Locus Microsatellite Typing (MLMT). MLMT revealed a total of 121 different genotypes with 91 unique genotypes and 30 repeated genotypes. Substantial genetic diversity was found with a strong genetic differentiation between the Leishmania populations from AM and P. However, exchanges were observed between these two endemic areas in which it seems that strains spread from AM to P. The genetic differentiations in these areas suggest strong epidemiological structuring. A model-based analysis using STRUCTURE revealed two main populations: population A (consisting of samples primarily from the P and AM endemic areas with MON-1 and non-MON-1 strains) and population B consisting of only MON-1 strains essentially from the AM endemic area. For four patients, we observed several isolates from different biological samples which provided insight into disease relapse and re-infection. These findings shed light on the transmission dynamics of parasites in humans. However, further data are required to confirm this hypothesis based on a limited sample set. This study represents the most extensive population analysis of L. infantum strains using MLMT conducted in France.
[Show abstract][Hide abstract]ABSTRACT: The distribution of phlebotomine sand flies is widely reported to be changing in Europe. This can be attributed to either the discovery of sand flies in areas where they were previously overlooked (generally following an outbreak of leishmaniasis or other sand fly-related disease) or to true expansion of their range as a result of climatic or environmental changes. Routine surveillance for phlebotomines in Europe is localized, and often one of the challenges for entomologists working in non-leishman-iasis endemic countries is the lack of knowledge on how to conduct, plan and execute sampling for phlebotomines, or how to adapt ongoing sampling strategies for other haematophagous diptera. This review brings together published and unpublished expert knowledge on sampling strategies for European phlebotomines of public health concern in order to provide practical advice on: how to conduct surveys; the collection and interpretation of field data; suitable techniques for the preservation of specimens obtained by different sampling methods; molecular techniques used for species identification ; and the pathogens associated with sand flies and their detection methods.
Full-text · Article · Aug 2015 · Bulletin of Entomological Research
[Show abstract][Hide abstract]ABSTRACT: Background
In sub-Saharan Africa, bovine tuberculosis (bTB) is a potential hazard for animals and humans health. The goal of this study was to improve our understanding of bTB epidemiology in Burkina Faso and especially Mycobacterium bovis transmission within and between the bovine and human populations.
Twenty six M. bovis strains were isolated from 101 cattle carcasses with suspected bTB lesions during routine meat inspections at the Bobo Dioulasso and Ouagadougou slaughterhouses. In addition, 7 M. bovis strains were isolated from 576 patients with pulmonary tuberculosis. Spoligotyping, RDAf1 deletion and MIRU-VNTR typing were used for strains genotyping. The isolation of M. bovis strains was confirmed by spoligotyping and 12 spoligotype signatures were detected. Together, the spoligotyping and MIRU-VNTR data allowed grouping the 33 M. bovis isolates in seven clusters including isolates exclusively from cattle (5) or humans (1) or from both (1). Moreover, these data (genetic analyses and phenetic tree) showed that the M. bovis isolates belonged to the African 1 (Af1) clonal complex (81.8%) and the putative African 5 (Af5) clonal complex (18.2%), in agreement with the results of RDAf1 deletion typing.
This is the first detailed molecular characterization of M. bovis strains from humans and cattle in Burkina Faso. The distribution of the two Af1 and putative Af5 clonal complexes is comparable to what has been reported in neighbouring countries. Furthermore, the strain genetic profiles suggest that M. bovis circulates across the borders and that the Burkina Faso strains originate from different countries, but have a country-specific evolution. The genetic characterization suggests that, currently, M. bovis transmission occurs mainly between cattle, occasionally between cattle and humans and potentially between humans. This study emphasizes the bTB risk in cattle but also in humans and the difficulty to set up proper disease control strategies in Burkina Faso.
[Show abstract][Hide abstract]ABSTRACT: For numerous infectious diseases affecting humans, clinical manifestations range from asymptomatic forms to severe pathologies. The originality of this study was its focus on asymptomatic carriers (ACs) of Leishmania infantum in southern France. The fundamental interest in these ACs is that they can be a reservoir of potentially pathogenic microorganisms. It remains to be established whether the parasitic genomes from ACs differ from those of patients. Multilocus microsatellite typing (MLMT) was used to investigate the genetic variation among 36 French strains of L. infantum. Nine Leishmania strains isolated from blood donors (ACs) were compared with 27 strains of L. infantum belonging to zymodemes, MON 1, 33 and 183. These strains were isolated from HIV positive or negative patients with visceral leishmaniasis (VL), cutaneous leishmaniasis (CL), from canine leishmaniasis (CanL) or from phlebotomine sandflies. MLMT data generated using 33 loci were analyzed by a Bayesian model-based clustering algorithm and construction of a phylogenetic tree based on genetic distances. Both analyses structured the MON-1 sample into two main clusters. Furthermore, genetic analysis demonstrated that these nine AC strains are divided into two clusters grouped with the MON-1 strains. One cluster with seven strains is related to, but different from, human symptomatic strains from the Alpes-Maritimes region whereas the other cluster has the two remaining strains together with CanL strains as well as one strain from a VL patient. Genetic diversity among AC was very weak since the nine Leishmania strains belong to only two genotypes. Genetic differentiations were evidenced between AC strains and non-AC strains and especially between AC and HIV+ populations, although these findings require confirmation with a larger sample size. We believe that our data explore for the first time, the genetic diversity among L. infantum from asymptomatic human carriers and reveal a weak polymorphism compared with Leishmania parasites isolated from human patients.
Full-text · Article · Feb 2013 · International journal for parasitology
[Show abstract][Hide abstract]ABSTRACT: This paper presents the first evaluation of the molecular epidemiology of Mycobacterium tuberculosis in Peru. We characterised 323 isolates using spoligotyping and mycobacterial interspersed repetitive units variable number tandem repeats (MIRU-VNTR) typing. We aimed to determine the levels of genetic diversity and genetic differentiation among and within Peruvian isolates and the epidemiological factors which may be driving patterns of population structure and evolution of M. tuberculosis in Peru. Our results compared to the fourth international spoligotyping database (SpolDB4) and MIRU-VNTRplus, show that the main M. tuberculosis families present are Latin American-Mediterranean, Haarlem, T, and Beijing. Bayesian clustering recovered 15 groups in the Peruvian M. tuberculosis isolates, among which two were composed mainly of orphans, implying the presence of native "Peruvian" strains not previously reported. Variable levels of association with drug resistance were observed, with Beijing genotypes not showing any association with multidrug resistance, while in other groups MIRU-VNTR loci 2, 23, 31, and 40 were found to be associated with the multidrug-resistant tuberculosis (MDR-TB) phenotype, suggesting that a linkage disequibrium between these MIRU and drug resistance loci may be present. Genetic differentiation was present among drug resistant and sensitive strains. Ethambutol appeared to be the main driver of differentiation, suggesting that strong selection pressure could have been exerted by drug treatment in Peru over recent years.
Full-text · Article · Feb 2012 · Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases
[Show abstract][Hide abstract]ABSTRACT: Clin Microbiol Infect 2011; 17: 1451–1461
This review gives an update of current knowledge on the clinical pleiomorphism of Leishmania, with a special emphasis on the case of asymptomatic carriage. The first part describes the numerous unusual expressions of the disease that occur besides the classic (visceral, cutaneous, and mucocutaneous) forms of leishmaniases. The second part deals with progress in the understanding of disease outcome in humans, and the possible future approaches to improve our knowledge in the field. The third part highlights the role of the too often neglected asymptomatic carrier compartment. This group could be key to understanding infraspecific differences in virulence and pathogenicity of the parasite, as well as identifying the genetic determinants involved in the expression of the disease.
Full-text · Article · Oct 2011 · Clinical Microbiology and Infection
[Show abstract][Hide abstract]ABSTRACT: Whereas Leishmania infantum, the agent of visceral leishmaniasis (VL), is well known in North Africa, very limited data exist on its spread in West Africa,
where mainly cutaneous leishmaniasis has been widely reported. Nevertheless, dogs infected with L. infantum were recently found in the Mont Rolland District in Senegal. To provide a better understanding of L. infantum epidemiology in this area, clinical and serological surveys were carried out to determine the seroprevalence of L. infantum-specific antibodies in the human population. In parallel, an analysis of environmental and individual factors associated
with Leishmania antigen seropositivity was conducted to identify potential risk factors for exposure. Although no cases of VL were detected
within this study, a large part of the population (73/315; 23%) was exposed to infection, with a strong age effect (being
>40 ;years old increased the risk of being seropositive). Moreover, the presence of Nebedaye trees (Moringa oleifera) and infected dogs in the household were factors increasing the risk of exposure in household members. These results may
provide important information to identify the still unknown sandfly species involved in transmission.
Full-text · Article · Jun 2011 · Transactions of the Royal Society of Tropical Medicine and Hygiene
[Show abstract][Hide abstract]ABSTRACT: In the context of global warming and the risk of spreading arthropod-borne diseases, the emergence and reemergence of leishmaniasis should not be neglected. In Senegal, over the past few years, cases of canine leishmaniasis have been observed. We aim to improve the understanding of the transmission cycle of this zoonosis, to determine the responsible species and to evaluate the risk for human health. An epidemiological and serological study on canine and human populations in the community of Mont Rolland (Thiès area) was conducted. The data showed a high seroprevalence of canine leishmaniasis (>40%) and more than 30% seropositive people. The dogs' seroprevalence was confirmed by PCR data (concordance > 0.85, Kappa > 0.7). The statistical analysis showed strong statistical associations between the health status of dogs and seropositivity, the number of positive PCRs, clinical signs and the number of Leishmania isolates. For the first time, the discriminative PCRs performed on canine Leishmania strains clearly evidenced that the pathogenic agent is Leishmania infantum. The results obtained show that transmission of this species is well established in this area. That the high incidence of seropositivity in humans may be a consequence of infection with this species is discussed.
Full-text · Article · Dec 2010 · Microbes and Infection
[Show abstract][Hide abstract]ABSTRACT: We used 12 microsatellite markers developed for Leishmania braziliensis to genotype 28 strains of the main species of the Leishmania guyanensis complex (i.e. L. guyanensis and L. panamensis) collected in Ecuador and Peru. The important heterozygote deficits observed in these populations are similar with the previous data obtained in L. braziliensis and raise again the debate on the reproductive mode of these protozoan parasites. The data showed genetic polymorphism and geographical differentiation giving information on population structure of the L. guyanensis complex. Regarding the two species, this study enhances again the debate on the taxonomic status of the different isolates belonging to L. guyanensis s.l. since the results showed substantial heterogeneity within this species complex. In conclusion, this study increases the number of available microsatellite loci for L. guyanensis species complex and raises fundamental biological questions. It confirms that microsatellite markers constitute good tools for population genetic studies on parasites of this complex.
[Show abstract][Hide abstract]ABSTRACT: A new clonal complex of Mycobacterium bovis present at high frequency in cattle from west central African countries has been described as the African 1 (Af1) clonal
complex. Here, the first intrafamilial cluster of human tuberculosis cases due to M. bovis Af1 clonal complex strains is reported. We discuss hypotheses regarding modes of transmission.
Full-text · Article · Oct 2010 · Journal of clinical microbiology
[Show abstract][Hide abstract]ABSTRACT: Human tuberculosis caused by Mycobacterium microti is rare, but its prevalence and clinical significance may have been underestimated. To the best of our knowledge, 21 cases have been reported in the literature in the last decade. We report six recent pulmonary cases caused by M. microti over a period of 5 years detected in French clinical mycobacteriology laboratories of the hospital network. Our data confirm the potential of M. microti to cause clinical illness in immunocompetent patients. M. microti grew slowly from specimens, delaying the final microbiological diagnosis. Therefore, patients with tuberculosis caused by M. microti could benefit from the use of rapid diagnostic molecular techniques directly on clinical samples. From a review of the literature and this study, a classical antituberculous therapy seems effective in treating patients with M. microti disease.
Full-text · Article · Aug 2010 · Journal of Medical Microbiology
[Show abstract][Hide abstract]ABSTRACT: Djibouti is an East African country with a high tuberculosis incidence. This study was conducted over a 2-month period in Djibouti, during which 62 consecutive patients with pulmonary tuberculosis (TB) were included. Genetic characterization of Mycobacterium tuberculosis, using mycobacterial interspersed repetitive-unit variable-number tandem-repeat typing and spoligotyping, was performed. The genetic and phylogenetic analysis revealed only three major families (Central Asian, East African Indian and T). The high diversity and linkage disequilibrium within each family suggest a long period of clonal evolution. A Bayesian approach shows that the phylogenetic structure observed in our sample of 62 isolates is very likely to be representative of the phylogenetic structure of the M. tuberculosis population in the total number of TB cases.
[Show abstract][Hide abstract]ABSTRACT: In leishmaniasis, cysteine protease b (cpb) multicopy genes have been extensively studied because of their implication in host-parasite interactions. In the Leishmania donovani complex, responsible for visceral leishmaniasis, a set of interesting polymorphisms has been revealed, such as copy sequence or expression according to the parasite's life stage. The single nucleotide polymorphisms observed among these copies could be related to clinical characteristics such as dermotropic versus viscerotropic status. CPB COOH-terminal extension (CTE) is mainly responsible for genetic variability among the copies and appears highly immunogenic. These results suggest that further study of the role of CPBs, especially CTE in clinical outcome, is warranted.
Preview · Article · Mar 2008 · Transactions of the Royal Society of Tropical Medicine and Hygiene
[Show abstract][Hide abstract]ABSTRACT: Twelve microsatellite loci of Leishmania braziliensis were examined, nine of which were developed in this work. Fifty-six Leishmania braziliensis were genotyped with these microsatellite loci. The 12 loci studied were polymorphic with the number of alleles ranging from five to 19, with a mean of 9.7 ± 4.1 and the observed heterozygosity averaging 0.425 ± 0.202. The important heterozygote deficits we observed (F(IS) = 0.41, P value = 0.004) appear incompatible with the heterozygote excess expected in clonal diploids. This last result could revive the clonality/sexuality debate regarding Leishmania. This work validates the potential use of these microsatellites for population genetics analysis.
Full-text · Article · Mar 2008 · Molecular Ecology Resources
[Show abstract][Hide abstract]ABSTRACT: Current procedures for diagnosing Leishmania parasites from patients involve invasive and dangerous tissue aspiration. We have developed a non-invasive and highly sensitive microculture method that can isolate parasites from the buffy coat of the patient's peripheral blood. The parasites were cultured in 96-well culture plates. Nineteen parasitologically proven visceral leishmaniasis (VL) patients were included in the study. Using this technique, we were able to isolate parasites from 16 (84%) samples. However, all 19 (100%) samples were positive on culture of splenic aspirates. We conclude that this technique is useful for the isolation and cryoconservation of parasites from patients' blood. This simple method could be tried as a first-instance alternative before other more sensitive procedures such as splenic aspirate; however, negative results should be confirmed by tests with higher sensitivity.