The search for bacterial insecticidal molecules for the prevention of vector-borne infectious diseases

Dans ce travail, nous apportons notre contribution sur le contrôle biologique des maladies vectorielles transmises essentiellement par le moustique. Cela en proposant plusieurs candidats bactériens, sources potentielles de composées biologiques à propriétés insecticides. On a isolé ces souches bactériennes à partir de 3 sources, à savoir, des souches cliniques de l'IHU méditerranée infection Marseille, du sol de Sénégal et un gite larvaire présentant une mortalité naturelle des larves de moustique. Les métabolites sécrétés par ces souches ont été testé par la suite sur des larves de moustiques. La souche la plus active était Serratia marcescens P400 et elle a été choisi pour la caractérisation de son composé actif. Les analyses montrent que la molécule active était probablement une amine. La Dibutyltetradecylamine a été commandé et s'y avéré très efficace sur les larves. On a également validé une technique de contrôle des maladies vectorielles canines sur le terrain en corseIn this work, we contribute to the biological control of vector-borne diseases transmitted mainly by mosquitoes. We proposed numerous bacteria candidates as potential sources of biological compounds with insecticide properties. We isolated these bacterial strains from 3 sources, namely, clinical strains of the Mediterranean IHU infection Marseille, sand-soil from Senegal and a larval breeding site presenting a natural mortality of mosquito larvae. The metabolites produced by these strains were subsequently tested on mosquito larvae. The most active strain was non-pigmented Serratia marcescens P400 and it was chosen for the characterization of its active compound. The preliminary results of its characterization showed that the active molecule was probably an amine. Dibutyltetradecylamine was ordered and when tested, it was highly effective on mosquito larvae. We validated also a multimodal-technique for the control of canine vector borne diseases in Corsica

Mosquito-Borne Diseases Emergence/Resurgence and How to Effectively Control It Biologically

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Biological Control ofAedes albopictus: Obtained from the New Bacterial Candidates with Insecticidal Activity

Vector-borne deadly pathogens cause more than 700,000 deaths annually. They are transmitted by several vectors, among which the mosquito is the most important. Chemical compounds often have devastating side effects, leading to the abandonment of the majority of them. Biological control has been performed by using formulations ofBacillus sphaericusandBacillus thuringiensis,but their intensive use has led to the emergence of resistance. Currently, the development of new alternative molecules is urgently needed, in order to use them in mosaics or in rotation with already known insecticides for the control of vectors, especially mosquitoes. Here, we attempted to identify bacterial species with potential anti-mosquito actions. Among bacterial strains isolated from dry sandy soil from Senegal, eleven strains from the Bacillales and Actinomycetales orders were chosen for the entomopathogenic activity experiments. Then, we tested their secondary metabolites, which were obtained from the supernatant fraction, and their cell wall and cytoplasmic compounds, which were found in the pellet fraction, inAedes albopictuslarvae, and compared the larval mortality rate with that obtained by using a commercial product. A total of 4/11 (36.36%) of the isolated species exhibited insecticidal activity.B. nealsonii, which is not a well-known bacterium, had the highest larvicidal effect with 70% of the larval mortality, which is highlighted for the first time. TheStreptomycesspecies we isolated seem to be potential new species, and 3/5 (60%) of them exhibited insecticidal activity. Our study reports provide potential candidates for the identification of active molecules to be developed for strengthening the biological control of infectious diseases agents transmitted by mosquitoes

Tabanids as possible pathogen vectors in Senegal (West Africa)

Background: Species of the Tabanidae are potent vectors of human and animal diseases, but they have not been thoroughly investigated to date. In Senegal (West Africa), little information is available on these dipterans. Our objective in this study was to investigate Senegalese tabanids and their diversity by using molecular and proteomics approaches, as well as their associated pathogens. Methods: A total of 171 female tabanids were collected, including 143 from Casamance and 28 from Niokolo-Koba. The samples were identified morphologically by PCR sequencing and by MALDI-TOF MS, and PCR analysis was employed for pathogen detection and blood-meal characterization. Results: The morphological identification revealed four species concordantly with the molecular identification: Atylotus fuscipes (79.5%), Tabanus guineensis (16.4%), Chrysops distinctipennis (3.5%) and Tabanus taeniola (0.6%) (not identified by PCR). The molecular investigation of pathogens revealed the presence of Trypanosoma theileri (6.6%), Leishmania donovani (6.6%), Setaria digitate (1.5%), Rickettsia spp. (5.1%) and Anaplasmataceae bacteria (0.7%) in A. fuscipes. Tabanus guineensis was positive for L. donovani (35.7%), S. digitate (3.6%) and Anaplasmataceae (17.8%). Leishmania donovani has been detected in 50% of C. distinctipennis specimens and the only T taeniola specimen. No Piroplasmida, Mansonella spp. or Coxeilla burnetii DNA was detected. In addition to humans (96.43%), Chlorocebus sabeus, a non-human primate, has been identified as a host of (3.57%) analysed tabanids. MALDI-TOF MS enabled us to correctly identify all tabanid species that had good quality spectra and to create a database for future identification. Conclusions: Tabanids in Senegal could be vectors of several pathogens threatening animal and public health. To fully characterize these dipterans, it is therefore necessary that researchers in entomology and infectiology employ molecular characterization and mass spectrometric techniques such as MALDI-TOF MS to analyse these dipterans in Senegal and West Africa

Multiple vector-borne pathogens of domestic animals in Egypt

International audienceVector Borne Diseases (VBDs) are considered emerging and re-emerging diseases that represent a global burden. The aim of this study was to explore and characterize vector-borne pathogens in different domestic animal hosts in Egypt. A total of 557 blood samples were collected from different animals using a convenience sampling strategy (203 dogs, 149 camels, 88 cattle, 26 buffaloes, 58 sheep and 33 goats). All samples were tested for multiple pathogens using quantitative PCR and standard PCR coupled with sequencing. We identified Theileria annulata and Babesia bigemina in cattle (15.9 and 1.1%, respectively), T . ovis in sheep and buffaloes (8.6 and 7.7%, respectively) and Ba . canis in dogs (0.5%) as well as Anaplasma marginale in cattle, sheep and camels (20.4, 3.4 and 0.7%, respectively) and Coxiella burnetii in sheep and goats (1.7 and 3%; respectively). New genotypes of An . centrale , An . ovis , An . platys -like and Borrelia theileri were found in cattle (1.1,3.4, 3.4 and 3.4%, respectively), An . platys -like in buffaloes (7.7%), An . marginale , An . ovis , An . platys -like and Bo . theileri in sheep (3.4, 1.7, 1.7 and 3.4%, respectively), An . platys , An . platys -like and Setaria digitata in camels (0.7, 5.4 and 0.7%, respectively) and Rickettsia africae -like, An . platys , Dirofilaria repens and Acanthocheilonema reconditum in dogs (1.5, 3.4, 1 and 0.5%, respectively). Co-infections were found in cattle, sheep and dogs (5.7, 1.7, 0.5%, respectively). For the first time, we have demonstrated the presence of several vector-borne zoonoses in the blood of domestic animals in Egypt. Dogs and ruminants seem to play a significant role in the epidemiological cycle of VBDs

Rodents as Hosts of Pathogens and Related Zoonotic Disease Risk

International audienceRodents are known to be reservoir hosts for at least 60 zoonotic diseases and are known to play an important role in their transmission and spread in different ways. We sampled different rodent communities within and around human settlements in Northern Senegal, an area subjected to major environmental transformations associated with global changes. Herein, we conducted an epidemiological study on their bacterial communities. One hundred and seventy-one (171) invasive and native rodents were captured, 50 from outdoor trapping sites and 121 rodents from indoor habitats, consisting of five species. The DNA of thirteen pathogens was successfully screened on the rodents' spleens. We found: 2.3% of spleens positive to Piroplasmida and amplified one which gave a potentially new species Candidatus "Theileria senegalensis"; 9.35% of Bartonella spp. and amplified 10, giving three genotypes; 3.5% of filariasis species; 18.12% of Anaplasmataceae species and amplified only 5, giving a new potential species Candidatus "Ehrlichia senegalensis"; 2.33% of Hepatozoon spp.; 3.5% of Kinetoplastidae spp.; and 15.2% of Borrelia spp. and amplified 8 belonging all to Borrelia crocidurae. Some of the species of pathogens carried by the rodents of our studied area may be unknown because most of those we have identified are new species. In one bacterial taxon, Anaplasma, a positive correlation between host body mass and infection was found. Overall, male and invasive rodents appeared less infected than female and native ones, respectively

Severe pneumonia in a street rat (Rattus norvegicus) caused by Rodentibacter rarus strain RMC2

Background: Rodents are one of the most dangerous reservoirs and carriers of infectious diseases. Gradually, rats have become predominant in cities, sometimes staying in close vicinity to humans, pets and other animals. Consequently, they tend to increase the transmission risk of pathogens. Case Description: Here, we report an original case of bacterial pneumonia in a street rat (Rattus norvegicus). The rat was found dead on a street in the chief town of Marseille (France) after being run over by a car. The necropsy of the corpse revealed generalized granulomatous pneumonia in almost all the pulmonary lobes. Lung lesions, predominantly multiple fibro-inflammatory areas are preassembly to the witness of an infectious etiology. Bacterial isolation was performed from lung tissues. Colonies were identified by MALDI-TOF MS and confirmed by 16S rRNA sequencing. The following bacteria were identified: Staphylococcus cohnii, Bordetella bronchiseptica, B. parapertussi, Corynebacterium glucuronolyticum, Pelistega suis and Rodentibacter rarus. Based on histopathological diagnosis and the avoidance approach, the most likely etiological agent of the pneumonia is therefore R. rarus, a little-known Pasteurellales bacterium that is closely related to R. pneumotropicus. Conclusion: These data emphasize the severity of R. rarus infection in rodents. Thus pointing out a potential risk for other animals (dogs, cats, birds) as well as humans. The health monitoring program for rodents and rabbits pasteurellosis should now include R. rarus. Therefore, the pathological effect of Rodentibacter species and/or strains needs to be better explored

Severe pneumonia in a street rat (Rattus norvegicus) caused by Rodentibacter rarus strain RMC2

International audienceBackground: Rodents are one of the most dangerous reservoirs and carriers of infectious diseases. Gradually, rats have become predominant in cities, sometimes staying in close vicinity to humans, pets, and other animals. Consequently, they tend to increase the transmission risk of pathogens. Case Description: Here, we report an original case of bacterial pneumonia in a street rat (Rattus norvegicus). The rat was found dead on a street in the chief town of Marseille (France) after being run over by a car. The necropsy of the corpse revealed generalized granulomatous pneumonia in almost all the pulmonary lobes. Lung lesions and predominantly multiple fibro-inflammatory areas are presumably the witness of an infectious etiology. Bacterial isolation was carried out from lung tissues. Colonies were identified by MALDI-TOF MS and confirmed by 16S rRNA sequencing. The following bacteria were identified: Staphylococcus cohnii, Bordetella bronchiseptica, Bordetella parapertussi, Corynebacterium glucuronolyticum, Pelistega suis and Rodentibacter rarus. Based on the histopathological diagnosis and the avoidance approach, the most likely etiological agent of pneumonia is therefore R. rarus, a little-known Pasteurellales bacterium that is closely related to Rodentibacter pneumotropicus. Conclusion: These data emphasize the severity of R. rarus infection in rodents. Thus, pointing out a potential risk for other animals (dogs, cats, and birds), as well as humans. The health monitoring program for rodents and rabbits pasteurellosis should now include R. rarus. Therefore, the pathological effect of the Rodentibacterspecies and/or strains needs to be better explored

Severe pneumonia in a street rat (Rattus norvegicus) caused by Rodentibacter rarus strain RMC2

Background: Rodents are one of the most dangerous reservoirs and carriers of infectious diseases. Gradually, rats have become predominant in cities, sometimes staying in close vicinity to humans, pets, and other animals. Consequently, they tend to increase the transmission risk of pathogens.Case Description: Here, we report an original case of bacterial pneumonia in a street rat (Rattus norvegicus). The rat was found dead on a street in the chief town of Marseille (France) after being run over by a car. The necropsy of the corpse revealed generalized granulomatous pneumonia in almost all the pulmonary lobes. Lung lesions and predominantly multiple fibro-inflammatory areas are presumably the witness of an infectious etiology. Bacterial isolation was carried out from lung tissues. Colonies were identified by MALDI-TOF MS and confirmed by 16S rRNA sequencing. The following bacteria were identified: Staphylococcus cohnii, Bordetella bronchiseptica, Bordetella parapertussi, Corynebacterium glucuronolyticum, Pelistega suis and Rodentibacter rarus. Based on the histopathological diagnosis and the avoidance approach, the most likely etiological agent of pneumonia is therefore R. rarus, a little-known Pasteurellales bacterium that is closely related to Rodentibacter pneumotropicus.Conclusion: These data emphasize the severity of R. rarus infection in rodents. Thus, pointing out a potential risk for other animals (dogs, cats, and birds), as well as humans. The health monitoring program for rodents and rabbits pasteurellosis should now include R. rarus. Therefore, the pathological effect of the Rodentibacter species and/or strains needs to be better explored

Co-infection of bacteria and protozoan parasites in Ixodes ricinus nymphs collected in the Alsace region, France

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