-
Frontiers in Immunology 2023Salivary glands from blood-feeding arthropods secrete several molecules that inhibit mammalian hemostasis and facilitate blood feeding and pathogen transmission. The...
BACKGROUND
Salivary glands from blood-feeding arthropods secrete several molecules that inhibit mammalian hemostasis and facilitate blood feeding and pathogen transmission. The salivary functions from , the main vector of Onchocerciasis in South America, remain largely understudied. Here, we have characterized a salivary protease inhibitor (Guianensin) from the blackfly .
MATERIALS AND METHODS
A combination of bioinformatic and biophysical analyses, recombinant protein production, in vitro and in vivo experiments were utilized to characterize the molecula mechanism of action of Guianensin. Kinetics of Guianensin interaction with proteases involved in vertebrate inflammation and coagulation were carried out by surface plasmon resonance and isothermal titration calorimetry. Plasma recalcification and coagulometry and tail bleeding assays were performed to understand the role of Guianensin in coagulation.
RESULTS
Guianensin was identified in the sialotranscriptome of adult flies and belongs to the Kunitz domain of protease inhibitors. It targets various serine proteases involved in hemostasis and inflammation. Binding to these enzymes is highly specific to the catalytic site and is not detectable for their zymogens, the catalytic site-blocked human coagulation factor Xa (FXa), or thrombin. Accordingly, Guianensin significantly increased both PT (Prothrombin time) and aPTT (Activated partial thromboplastin time) in human plasma and consequently increased blood clotting time . Guianensin also inhibited prothrombinase activity on endothelial cells. We show that Guianensin acts as a potent anti-inflammatory molecule on FXa-induced paw edema formation in mice.
CONCLUSION
The information generated by this work highlights the biological functionality of Guianensin as an antithrombotic and anti-inflammatory protein that may play significant roles in blood feeding and pathogen transmission.
Topics: Mice; Humans; Animals; Simuliidae; Hemostatics; Endothelial Cells; Hemostasis; Anti-Inflammatory Agents; Inflammation; Salivary Proteins and Peptides; Mammals
PubMed: 37469515
DOI: 10.3389/fimmu.2023.1163367 -
Ecology and Evolution Jul 2023Today, the application of ecological indicators based on organisms has replaced traditional saprobic approaches for assessment of the quality of rivers impaired due to...
Today, the application of ecological indicators based on organisms has replaced traditional saprobic approaches for assessment of the quality of rivers impaired due to organic pollution and some other environmental disturbances. This study aimed to weigh the quality of the Ojarud River in Ardabil, Iran, applying biological and physiological indices of macro-invertebrates. A total of 12,524 samplings were fulfilled at four stations (S1, S2, S3, S4) from the headstream to downstream by a Surber sampler (30 × 30 cm) from June/2020 to April/2021. All year round, the highest frequent families were Chironomidae (2658), Simuliidae (1025) from Diptera and Caenidae (1855), and Baetidae (724) from Ephemeroptera. The diversity pattern was analyzed by PAST software, and Primer 7 (BIO-ENV analysis) was utilized to understand what factor has the most impact on the distribution of macro-invertebrates. The least similarity of S4 to other stations was recognized by Cluster analysis. As per the ANOSIM (analysis of similarities), a statistically significant difference in the macroinvertebrates' frequency was established between S3 and other stations ( = .0001, = .63). Moreover, the relationship between heavy metals and macro-invertebrate showed that the three families of Simuliidae, Gomphidae, and Caenidae had a positive correlation with the concentrations of heavy metals in the sediment. As per the Ephemeroptera, Plecoptera and Trichoptera index, the water quality was placed in the "excellent" class, but the Biological Monitoring Working Party and Hilsenhoff Family Biotic Index indices scored the water quality "good" class at S1 and the "poor" class at S3. Based on the results of this study, the use of physicochemical and hydro-morphological indicators can support the biological indicators but cannot replace them. In addition, careful evaluation of biological indicators is required to develop conservation strategies.
PubMed: 37465610
DOI: 10.1002/ece3.10310 -
Acta Tropica Sep 2023Simulium damnosum s.l., the most important vector of onchocerciasis in Africa, is a complex of sibling species described on the basis of differences in their larval... (Review)
Review
Simulium damnosum s.l., the most important vector of onchocerciasis in Africa, is a complex of sibling species described on the basis of differences in their larval polytene chromosomes. These (cyto) species differ in their geographical distributions, ecologies and epidemiological roles. In Togo and Benin, distributional changes have been recorded as a consequence of vector control and environmental changes (e.g. creation of dams, deforestation), with potential epidemiological consequences. We review the distribution of cytospecies in Togo and Benin and report changes observed from 1975 to 2018. The elimination of the Djodji form of S. sanctipauli in south-western Togo in 1988 seems to have had no long-term effects on the distribution of the other cytospecies, despite an initial surge by S. yahense. Although we report a general tendency for long-term stability in most cytospecies' distributions, we also assess how the cytospecies' geographical distributions have fluctuated and how they vary with the seasons. In addition to seasonal expansions of geographical ranges by all species except S. yahense, there are seasonal variations in the relative abundances of cytospecies within a year. In the lower Mono river, the Beffa form of S. soubrense predominates in the dry season but is replaced as the dominant taxon in the rainy season by S. damnosum s.str. Deforestation was previously implicated in an increase of savanna cytospecies in southern Togo (1975-1997), but our data had little power to support (or refute) suggestions of a continuing increase, partly because of a lack of recent sampling. In contrast, the construction of dams and other environmental changes including climate change seem to be leading to decreases in the populations of S. damnosum s.l. in Togo and Benin. If so, combined with the disappearance of the Djodji form of S. sanctipauli, a potent vector, plus historic vector control actions and community directed treatments with ivermectin, onchocerciasis transmission in Togo and Benin is much reduced compared with the situation in 1975.
Topics: Animals; Simuliidae; Seasons; Togo; Onchocerciasis; Benin; Insect Vectors
PubMed: 37339715
DOI: 10.1016/j.actatropica.2023.106970 -
PLoS Neglected Tropical Diseases May 2023Onchocerciasis, also known as "river blindness", is caused by the bite of infected female blackflies (genus Simuliidae) that transmit the parasite Onchocerca volvulus. A...
BACKGROUND
Onchocerciasis, also known as "river blindness", is caused by the bite of infected female blackflies (genus Simuliidae) that transmit the parasite Onchocerca volvulus. A high onchocerciasis microfarial load increases the risk to develop epilepsy in children between the ages of 3 and 18 years. In resource-limited settings in Africa where onchocerciasis has been poorly controlled, high numbers of onchocerciasis-associated epilepsy (OAE) are reported. We use mathematical modeling to predict the impact of onchocerciasis control strategies on the incidence and prevalence of OAE.
METHODOLOGY
We developed an OAE model within the well-established mathematical modelling framework ONCHOSIM. Using Latin-Hypercube Sampling (LHS), and grid search technique, we quantified transmission and disease parameters using OAE data from Maridi County, an onchocerciasis endemic area, in southern Republic of South Sudan. Using ONCHOSIM, we predicted the impact of ivermectin mass drug administration (MDA) and vector control on the epidemiology of OAE in Maridi.
PRINCIPAL FINDINGS
The model estimated an OAE prevalence of 4.1% in Maridi County, close to the 3.7% OAE prevalence reported in field studies. The OAE incidence is expected to rapidly decrease by >50% within the first five years of implementing annual MDA with good coverage (≥70%). With vector control at a high efficacy level (around 80% reduction of blackfly biting rates) as the sole strategy, the reduction is slower, requiring about 10 years to halve the OAE incidence. Increasing the efficacy levels of vector control, and implementing vector control simultaneously with MDA, yielded better results in preventing new cases of OAE.
CONCLUSIONS/SIGNIFICANCES
Our modeling study demonstrates that intensifying onchocerciasis eradication efforts could substantially reduce OAE incidence and prevalence in endemic foci. Our model may be useful for optimizing OAE control strategies.
Topics: Child; Animals; Female; Humans; Child, Preschool; Adolescent; Onchocerciasis; South Sudan; Onchocerciasis, Ocular; Ivermectin; Onchocerca volvulus; Epilepsy; Prevalence; Simuliidae; Blindness
PubMed: 37235598
DOI: 10.1371/journal.pntd.0011320 -
Insects May 2023Females of frog-biting midges (Corethrellidae) obtain their blood meals from male calling frogs. While the morphology of the feeding apparatus is well studied in...
Females of frog-biting midges (Corethrellidae) obtain their blood meals from male calling frogs. While the morphology of the feeding apparatus is well studied in hematophagous Diptera that impact humans, frog-biting midges have received far less attention. We provide a detailed micromorphological examination of the piercing blood-sucking proboscis and maxillary palpus in three species using scanning electron microscopy and histological semi-thin sectioning. We also compare the sensilla found on the proboscis tip and the palpus of with other piercing blood-sucking Diptera. spp. have a proboscis length of about 135 µm, equipped with delicate mandibular piercing structures composing the food canal together with the labrum and hypopharynx. Their proboscis composition is plesiomorphic and more similar to other short-proboscid hematophagous Culicomorpha (e.g., Simuliidae), in contrast to the phylogenetically more closely related long-proboscid Culicidae. As in other short-proboscid taxa, the salivary canal in spp. transitions into an open salivary groove with one mandible forming a seal, whereas in Culicidae the salivary canal is closed until the tip of the proboscis. We discuss the possible functional constraints of very short, piercing blood-sucking proboscises (e.g., dimensions of host blood cells) that may limit the size of the food canal.
PubMed: 37233088
DOI: 10.3390/insects14050461 -
Anais Da Academia Brasileira de Ciencias 2023Secondary production is the formation of heterotrophic biomass across time, which integrates several important ecological processes that affect the life of organisms,...
Secondary production is the formation of heterotrophic biomass across time, which integrates several important ecological processes that affect the life of organisms, populations, communities and ecosystems, but its study has poor developed in South America. The objectives of this work were to describe the diversity of benthic macroinvertebrate assemblages in terms of abundance and biomass, and to quantify their secondary production for the first time in Andean rivers. A quantitative sampling scheme was implemented, using a Surber sampler, in three forested streams. Physical-chemical variables, nutrients, organic matter and chlorophyll were measured also. The macroinvertebrates were separated and identified mostly at the species level. Each taxon was assigned to a functional feeding group. Secondary production was estimated for 38 taxa, mostly Diptera, Trichoptera, Coleoptera, and Ephemeroptera. The annual production varied from 3769 to 13916 mg dry mass m-2 y-1. Most abundant taxa were also those with higher production, dominated by Ephemeroptera (Baetidae), Trichoptera (Hydropsychidae) and Diptera (Chironomidae and Simuliidae). Density, biomass, and production of collectors and predators were much higher than the other feeding groups. We expect that our results will be useful to evaluate the effects on stream functioning produced by global warming and other anthropogenic disturbances in our region.
Topics: Animals; Biomass; Ecosystem; Rivers; Chlorophyll; Coleoptera; Ephemeroptera; Holometabola
PubMed: 37222363
DOI: 10.1590/0001-3765202320220095 -
International Health Mar 2024By 1987, onchocerciasis in Niger had been successfully controlled in the six endemic river basins. In 2017, onchocerciasis elimination mapping (OEM) was carried out to...
BACKGROUND
By 1987, onchocerciasis in Niger had been successfully controlled in the six endemic river basins. In 2017, onchocerciasis elimination mapping (OEM) was carried out to determine if there was any ongoing transmission in the country as a whole.
METHODS
The recommended OEM procedures were implemented.
RESULTS
Ten districts, that included 35 villages, required field investigation as sites of possible transmission. None of these were found capable of supporting black fly breeding, nor was there any evidence of the presence of Simulium sp. flies.
CONCLUSIONS
The implementation of OEM indicates that there is no transmission of onchocerciasis currently taking place in these newly assessed sites in Niger.
Topics: Animals; Humans; Onchocerciasis; Niger; Africa, Western; Simuliidae; Ivermectin
PubMed: 37183774
DOI: 10.1093/inthealth/ihad032 -
Science Progress 2023Freshwater ecosystems, especially springs, are highly sensitive to environmental changes. They are also excellent natural laboratories because of their stable...
Freshwater ecosystems, especially springs, are highly sensitive to environmental changes. They are also excellent natural laboratories because of their stable conditions, reducing the number of variables to be considered in field studies. We examined the composition, dynamics and colonisation patterns of macroinvertebrates with respect to canopy coverage and time of day in which available areas are actively colonised. We used artificial substrates that mimicked the natural habitat structure at an isolated karst spring and recovered exposed substrates every 12 h. Physico-chemical parameters of water did not differ significantly regardless of canopy cover. The most numerous representatives and the pioneering champions were larvae of Baetidae (Ephemeroptera) and Chironomidae (Diptera). Simuliidae were also among the most successful pioneering species. Most observed groups more actively colonised substrates in the closed canopy area. Oligochaeta and were more numerous on substrates in the open canopy area. Individuals of all analysed groups showed day-night migration patterns and were more active at night. Coleoptera ( sp.) were the poorest (re)colonisers among the analysed taxa.
Topics: Humans; Animals; Ecosystem; Environmental Monitoring; Chironomidae
PubMed: 37042031
DOI: 10.1177/00368504231166956 -
Scientific Reports Apr 2023Onchocerciasis is a parasitic disease transmitted by black flies. Human onchocerciasis is a public health and socioeconomic problem in Nigeria. Its prevalence and...
Onchocerciasis is a parasitic disease transmitted by black flies. Human onchocerciasis is a public health and socioeconomic problem in Nigeria. Its prevalence and morbidity have reduced over the years because of control efforts especially, Mass Drug Administration with ivermectin. The current goal is to eliminate the disease transmission by 2030. Understanding the changes in transmission patterns in Cross River State is critical to elimination of onchocerciasis in Nigeria. This study was designed to determine the transmission dynamics of onchocerciasis in Cross River State after over two decades of mass ivermectin distribution in endemic communities. Agbokim, Aningeje, Ekong Anaku and Orimekpang are four endemic communities from three Local Government Areas of the State selected for this study. Transmission indices such as infectivity rates, biting rates and transmission potentials, parity rates and diurnal biting activities were determined. A total of 15,520 adult female flies were caught on human baits, Agbokim (2831), Aningeje (6209), Ekong Anaku (4364) and Orimekpang (2116). A total of 9488 and 5695 flies were collected during the rainy and dry seasons respectively in the four communities studied. The differences in relative abundance among the communities were statistically significant (P < 0.001). Monthly and seasonal fly numbers varied significantly (P < 0.008). There were differences in diurnal biting activities of flies in this study at different hours of the day and different months. The peak monthly biting rates were 5993 (Agbokim, October), 13,134 (Aningeje, October), 8680 (Ekong Anaku, October) and 6120 (Orimekpang, September) bites/person/month while the lowest monthly biting rates were 400 (Agbokim, November), 2862 (Aningeje, August), 1405 (Ekong Anaku, January) and 0.0 (Orimekpang, November and December) bites/person/month. Differences in biting rates among the study communities were significant (P < 0.001). The peak monthly transmission potential in Aningeje was 160 infective bites/person/month in the month of February while the lowest (except for months with no transmission) was 42 infective bites/person/month in the month of April. All other study sites had no ongoing transmission in this study. Transmission studies showed that there is progress toward transmission interruption especially in 3 out of the four studied areas. Molecular O-150 poolscreen studies is required to confirm the true transmission situation in the areas.
Topics: Adult; Animals; Female; Humans; Ivermectin; Onchocerciasis; Nigeria; Mass Drug Administration; Insect Bites and Stings; Insect Vectors; Simuliidae
PubMed: 37012274
DOI: 10.1038/s41598-023-31446-6 -
Acta Tropica Apr 2023Female Simulium damnosum s.l. were caught at a site in a savannah zone beside the Mono River in Togo and at varying distances westwards perpendicular to it in an...
Female Simulium damnosum s.l. were caught at a site in a savannah zone beside the Mono River in Togo and at varying distances westwards perpendicular to it in an experiment to investigate short-range dispersal by the flies. The numbers of flies caught and the percentages that were parous decreased with increasing distance from the river, the latter suggesting that nulliparous flies disperse on average further than parous flies. The decreases were quantified using statistically significant multiple regressions involving distances from the river and the days since the start of the experiment because there was much day-to-day variation, probably attributable to the flies' gonotrophic cycles. For future modelling purposes a relationship between numbers caught and distance alone was also estimated for both numbers caught and parous rates. Of the different members of the S. damnosum species complex identified in larval samples, S. damnosum s.str. predominated (66.7%), with S. squamosum accounting for 25.5% and the Beffa form of S. soubrense for 7.8%, proportions that were not significantly different from those of adults identified at the river and 10 km away. A small sub-sample of dissected parous flies showed that transmission was occurring at the riverside and at 10 km away from the river.
Topics: Animals; Female; Simuliidae; Onchocerciasis; Insect Vectors; Togo; Rivers
PubMed: 36781096
DOI: 10.1016/j.actatropica.2023.106863