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Microorganisms Aug 2022Arthropods' vectors-those of a large variety of families, including Culicidae, Simuliidae, Psychodidae, Ixodidae, Agarsidae, Pulicidae, Glossinidae, Reduviidae, and...
Arthropods' vectors-those of a large variety of families, including Culicidae, Simuliidae, Psychodidae, Ixodidae, Agarsidae, Pulicidae, Glossinidae, Reduviidae, and Tabanidae [...].
PubMed: 36013973
DOI: 10.3390/microorganisms10081555 -
Research and Reports in Tropical... 2021Mansonellosis is caused by three filarial parasite species from the genus that commonly produce chronic human microfilaraemias: and . The disease is widespread in... (Review)
Review
Mansonellosis is caused by three filarial parasite species from the genus that commonly produce chronic human microfilaraemias: and . The disease is widespread in Africa, the Caribbean and South and Central America, and although it is typically asymptomatic it has been associated with mild pathologies including leg-chills, joint-pains, headaches, fevers, and corneal lesions. No robust mansonellosis disease burden estimates have yet been made and the impact the disease has on blood bank stocks and the monitoring of other filarial diseases is not thought to be of sufficient public health importance to justify dedicated disease management interventions. Mansonellosis´s Ceratopogonidae and Simuliidae vectors are not targeted by other control programmes and because of their small size and out-door biting habits are unlikely to be affected by interventions targeting other disease vectors like mosquitoes. The ivermectin and mebendazole-based mass drug administration (iMDA and mMDA) treatment regimens deployed by the WHO´s Elimination of Neglected Tropical Diseases (ESPEN) programme and its forerunners have, however, likely impacted significantly on the mansonellosis disease burden, principally by reducing the transmission of in Africa. The increasingly popular plan of using iMDA to control malaria could also affect parasite prevalence and transmission in Latin America in the future. However, a potentially far greater mansonellosis disease burden impact is likely to come from short-course curative anti- therapeutics, which are presently being developed for onchocerciasis and lymphatic filariasis treatment. Even if the WHO´s ESPEN programme does not choose to deploy these drugs in MDA interventions, they have the potential to dramatically increase the financial and logistical feasibility of effective mansonellosis management. There is, thus, now a fresh and urgent need to better characterise the disease burden and eco-epidemiology of mansonellosis so that effective management programmes can be designed, advocated for and implemented.
PubMed: 34079424
DOI: 10.2147/RRTM.S274684 -
International Journal of Infectious... Mar 2021Nodding syndrome is one of several forms of onchocerciasis-associated epilepsy (OAE) seen among children in areas formerly hyperendemic for the transmission of... (Review)
Review
Nodding syndrome is one of several forms of onchocerciasis-associated epilepsy (OAE) seen among children in areas formerly hyperendemic for the transmission of Onchocerca volvulus. These forms of epilepsy are highly prevalent and clustered in certain villages located close to blackfly (Diptera: Simuliidae) breeding sites. OAE presents with a wide spectrum of seizures, including generalized tonic-clonic and head nodding seizures, impaired cognitive function, growth stunting and delayed puberty. In 2014, the present authors published a perspective paper in this journal which hypothesized that nodding syndrome may be caused by either a neurotropic virus transmitted by blackflies or an endosymbiont present within the O. volvulus parasite. Seven years later, this critical review presents progress in nodding syndrome research, and assesses whether it is still plausible that a neurotropic virus or endosymbiont could be the cause.
Topics: Animals; Biomedical Research; Humans; Nodding Syndrome; Onchocerca volvulus; Onchocerciasis; Prevalence
PubMed: 33556614
DOI: 10.1016/j.ijid.2021.02.006 -
Revue Scientifique Et Technique... Dec 1994The biology, veterinary importance and control of certain Nematocera are described and discussed. Culicoides spp. (family Ceratopogonidae) transmit the arboviruses of... (Review)
Review
The biology, veterinary importance and control of certain Nematocera are described and discussed. Culicoides spp. (family Ceratopogonidae) transmit the arboviruses of bluetongue (BT), African horse sickness (AHS), bovine ephemeral fever (BEF) and Akabane. Some other arboviruses have been isolated from these species, while fowl pox has been transmitted experimentally by Culicoides. These insects are vectors of the parasitic protozoans Leucocytozoon caulleryi and Haemoproteus nettionis, and the parasitic nematodes Onchocerca gutturosa, O. gibsoni and O. cervicalis. They also cause recurrent summer hypersensitivity in horses, ponies, donkeys, cattle and sheep. Farm animals can die as a result of mass attack by Simulium spp., which are also vectors of Leucocytozoon simondi, L. smithi and the filariae O. gutturosa, O. linealis and O. ochengi. Venezuelan equine encephalomyelitis (VEE) and Rift Valley fever (RVF) have been isolated from simuliids, and vesicular stomatitis virus New Jersey strain has been replicated in Simulium vittatum. Simuliids are well known as vectors of O. volvulus, the cause of human onchocercosis (river blindness). The family Psychodidae includes the genera Phlebotomus and Lutzomyia (subfamily Phlebotominae), vectors of Leishmania spp. in humans, dogs and other mammals. Vesicular stomatitis virus Indiana strain has been regularly isolated from phlebotomine sandflies. Mass attack by mosquitoes can also prove fatal to farm animals. Mosquitoes are vectors of the viruses of Akabane, BEF, RVF, Japanese encephalitis, VEE, western equine encephalomyelitis, eastern equine encephalomyelitis and west Nile meningoencephalitis, secondary vectors of AHS and suspected vectors of Israel turkey meningoencephalitis. The viruses of hog cholera, fowl pox and reticuloendotheliosis, the rickettsiae Eperythrozoon ovis and E. suis, and the bacterium Borrelia anserina are mechanically transmitted by mosquitoes. These insects also induce allergic dermatitis in horses. They transmit several filarial worms of both animals and humans, and are of great medical importance as vectors of major human diseases, including malaria, yellow fever, dengue fever and many more diseases caused by arboviruses.
Topics: Animals; Animals, Domestic; Ceratopogonidae; Communicable Diseases; Culicidae; Diptera; Ectoparasitic Infestations; Female; Insect Control; Insect Vectors; Male; Psychodidae; Simuliidae
PubMed: 7711309
DOI: 10.20506/rst.13.4.819 -
Toxics Jul 2022This study is the first to investigate the ingestion of microplastics (MPs), plasticizers, additives, and particles of micro-litter < 100 μm by larvae of Simuliidae...
This study is the first to investigate the ingestion of microplastics (MPs), plasticizers, additives, and particles of micro-litter < 100 μm by larvae of Simuliidae (Diptera) in rivers. Blackflies belong to a small cosmopolitan insect family whose larvae are present alongside river courses, often with a torrential regime, up to their mouths. Specimens of two species of blackfly larvae, Simulium equinum and Simulium ornatum, were collected in two rivers in Central Italy, the Mignone and the Treja. Small microplastics (SMPs, <100 μm), plasticizers, additives, and other micro-litter components, e.g., natural and non-plastic synthetic fibers (APFs) ingested by blackfly larvae were, for the first time, quantified and concurrently identified via MicroFTIR. The pretreatment allowed for simultaneous extraction of the ingested SMPs and APFs. Strong acids or strong oxidizing reagents and the application of temperatures well above the glass transition temperature of polyamide 6 and 6.6 (55−60 °C) were not employed to avoid further denaturation/degradation of polymers and underestimating the quantification. Reagent and procedural blanks did not show any SMPs or APFs. The method’s yield was >90%. Differences in the abundances of the SMPs and APFs ingested by the two species under exam were statistically significant. Additives and plasticizers can be specific to a particular polymer; thus, these compounds can be proxies for the presence of plastic polymers in the environment.
PubMed: 35878288
DOI: 10.3390/toxics10070383 -
Expert Review of Anti-infective Therapy Apr 2017Onchocerca volvulus infects in excess of 15 million people. The vectors are Simulium blackflies, varieties of which differ in their ecologies, behavior and vectorial... (Review)
Review
Onchocerca volvulus infects in excess of 15 million people. The vectors are Simulium blackflies, varieties of which differ in their ecologies, behavior and vectorial abilities. Control of the vectors and mass administrations of ivermectin have succeeded in reducing prevalences with elimination achieved in some foci, particularly in Central and southern America. In Africa, progress towards elimination has been less successful. Areas covered: Even with community directed treatment with ivermectin (CDTI), control has been difficult in African areas with initial prevalences in excess of 55%, especially if only annual treatments are dispensed. This is partly attributable to insufficient coverage, but the appearance of incipiently resistant non-responding parasites and lack of attention to vector biology in modeling and planning outcomes of intervention programmes have also played their parts, with recrudescence now appearing in some treated areas. Expert commentary: The biology of onchocerciasis is complex involving different vectors with differing abilities to transmit parasites, diverse pathologies related to geographical and parasite variations and endosymbionts in both parasite and vector. Modeling to predict epidemiological and control outcomes is addressing this complexity but more attention needs to be given to the vectors' roles to further understanding of where and when control measures will succeed.
Topics: Africa; Albendazole; Animals; Anthelmintics; Central America; Doxycycline; Humans; Insect Vectors; Insecticides; Ivermectin; Macrolides; Onchocerca volvulus; Onchocerciasis; Simuliidae; South America
PubMed: 28117596
DOI: 10.1080/14787210.2017.1286980 -
Bulletin of the World Health... 1964
PubMed: 20604184
DOI: No ID Found -
Toxins Mar 2014Bacillus thuringiensis subsp. israelensis (Bti) is the first Bacillus thuringiensis to be found and used as an effective biological control agent against larvae of many... (Review)
Review
Bacillus thuringiensis subsp. israelensis (Bti) is the first Bacillus thuringiensis to be found and used as an effective biological control agent against larvae of many mosquito and black fly species around the world. Its larvicidal activity resides in four major (of 134, 128, 72 and 27 kDa) and at least two minor (of 78 and 29 kDa) polypeptides encoded respectively by cry4Aa, cry4Ba, cry11Aa, cyt1Aa, cry10Aa and cyt2Ba, all mapped on the 128 kb plasmid known as pBtoxis. These six δ-endotoxins form a complex parasporal crystalline body with remarkably high, specific and different toxicities to Aedes, Culex and Anopheles larvae. Cry toxins are composed of three domains (perforating domain I and receptor binding II and III) and create cation-selective channels, whereas Cyts are composed of one domain that acts as well as a detergent-like membrane perforator. Despite the low toxicities of Cyt1Aa and Cyt2Ba alone against exposed larvae, they are highly synergistic with the Cry toxins and hence their combinations prevent emergence of resistance in the targets. The lack of significant levels of resistance in field mosquito populations treated for decades with Bti-bioinsecticide suggests that this bacterium will be an effective biocontrol agent for years to come.
Topics: Animals; Anti-Bacterial Agents; Antineoplastic Agents; Bacillus thuringiensis; Bacillus thuringiensis Toxins; Bacterial Proteins; Biological Control Agents; Culicidae; Endotoxins; Hemolysin Proteins; Insecticide Resistance; Insecticides; Larva; Mosquito Control; Simuliidae
PubMed: 24686769
DOI: 10.3390/toxins6041222 -
Parasites & Vectors Dec 2022Documentation on water mites in Spain is scarce, as is information on the parasite-host relationship between certain water mite species and representatives of the...
BACKGROUND
Documentation on water mites in Spain is scarce, as is information on the parasite-host relationship between certain water mite species and representatives of the dipteran family Simuliidae. The discomfort caused to humans and animals by black flies seems to be increasing in recent years. In this context, an investigation of parasitic water mites is of great importance, not only from the point of view of biodiversity, but also in terms of their potential to control black fly populations.
METHODS
Rivers across a wide region of eastern Spain were sampled to determine the specific richness of simuliid dipterans and to investigate their possible parasites, such as water mites, mermithid nematodes and microsporidia (fungal microbes). Data on environmental variables, abundance, prevalence and intensity of parasitism on the collected specimens were analyzed.
RESULTS
In 10 streams, 15,396 simuliid pupae were collected and checked for the presence of water mite larvae; 426 pupae in seven streams were found to be associated with water mite larvae. Of the 21 simuliid species identified based on morphological characters, eight were found to be associated with water mite larvae. Water mite infection was not equally distributed among black fly species. Also, the prevalence of parasitism was low and differed among simuliid species, ranging from one to 13 water mites per black fly pupa. Variation at the intra- and interspecific levels was detected in terms of the number of water mites inside the black fly cocoons. Free-living deutonymphal and adult water mites representing 15 different species of six genera and five families were morphologically identified. The taxonomic identity of the parasitic mite larvae is unclear at present. Morphologically, they fit descriptions of larval Sperchon (Hispidosperchon) algeriensis Lundblad, 1942, but the possibility cannot be excluded that they represent Sperchon algeriensis, the most abundant species at the adult stage in this study and unknown at the larval stage, or even another species of the genus. A molecular analysis produced for the first time cytochrome oxidase I gene sequences for S. algeriensis.
CONCLUSIONS
Our results contribute to current knowledge on Spanish Hydrachnidia and their relationships with simuliids as hosts. However, further research is needed to evaluate the diversity, distribution, bioecology and prevalence of this parasitism.
Topics: Humans; Animals; Simuliidae; Mites; Parasites; Water; Spain; Pupa; Larva
PubMed: 36528694
DOI: 10.1186/s13071-022-05610-2 -
PLoS Neglected Tropical Diseases Mar 2022Onchocerciasis ("river blindness"), is a neglected tropical disease caused by the filarial nematode Onchocerca volvulus and transmitted to humans through repeated bites... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Onchocerciasis ("river blindness"), is a neglected tropical disease caused by the filarial nematode Onchocerca volvulus and transmitted to humans through repeated bites by infective blackflies of the genus Simulium. Moxidectin was approved by the United States Food and Drug Administration in 2018 for the treatment of onchocerciasis in people at least 12 years of age. The pharmacokinetics of orally administered moxidectin in 18- to 60-year-old men and women infected with Onchocerca volvulus were investigated in a single-center, ivermectin-controlled, double-blind, randomized, single-ascending-dose, ascending severity of infection study in Ghana.
METHODOLOGY/PRINCIPAL FINDINGS
Participants were randomized to either a single dose of 2, 4 or 8 mg moxidectin or ivermectin. Pharmacokinetic samples were collected prior to dosing and at intervals up to 12 months post-dose from 33 and 34 individuals treated with 2 and 4 mg moxidectin, respectively and up to 18 months post-dose from 31 individuals treated with 8 mg moxidectin. Moxidectin plasma concentrations were determined using high-performance liquid chromatography with fluorescence detection. Moxidectin plasma AUC0-∞ (2 mg: 26.7-31.7 days*ng/mL, 4 mg: 39.1-60.0 days*ng/mL, 8 mg: 99.5-129.0 days*ng/mL) and Cmax (2mg, 16.2 to17.3 ng/mL, 4 mg: 33.4 to 35.0 ng/mL, 8 mg: 55.7 to 74.4 ng/mL) were dose-proportional and independent of severity of infection. Maximum plasma concentrations were achieved 4 hours after drug administration. The mean terminal half-lives of moxidectin were 20.6, 17.7, and 23.3 days at the 2, 4 and 8 mg dose levels, respectively.
CONCLUSION/SIGNIFICANCE
We found no relationship between severity of infection (mild, moderate or severe) and exposure parameters (AUC0-∞ and Cmax), T1/2 and Tmax for moxidectin. Tmax, volume of distribution (V/F) and oral clearance (CL/F) are similar to those in healthy volunteers from Europe. From a pharmacokinetic perspective, moxidectin is an attractive long-acting therapeutic option for the treatment of human onchocerciasis.
Topics: Administration, Oral; Adolescent; Adult; Animals; Female; Humans; Ivermectin; Macrolides; Male; Middle Aged; Onchocerca volvulus; Onchocerciasis; Simuliidae; Young Adult
PubMed: 35333880
DOI: 10.1371/journal.pntd.0010005