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Scientific Reports Jun 2024Malaria in eastern Indonesia remains high despite significant reduction and elimination in other parts of the country. A rapid entomological assessment was conducted in...
Malaria in eastern Indonesia remains high despite significant reduction and elimination in other parts of the country. A rapid entomological assessment was conducted in eight high malaria endemic regencies of Papua Province, Indonesia, to expedite malaria elimination efforts in this region. This study aims to characterize specific, actionable endpoints toward understanding where and when malaria transmission is happening, where interventions may function best, and identify gaps in protection that result in continued transmission. The entomological assessment included identifying potential vectors through human landing catch (HLC), indoor morning and night resting collections, identification of larval sites through surveillance of water bodies, and vector incrimination toward understanding exposure to malaria transmission. Human landing catches (HLCs) and larval collections identified 10 Anopheles species, namely Anopheles koliensis, Anopheles punctulatus, Anopheles farauti, Anopheles hinesorum, Anopheles longirostris, Anopheles peditaeniatus, Anopheles tesselatus, Anopheles vagus, Anopheles subpictus and Anopheles kochi. The most common and abundant species found overall were An. koliensis and An. punctulatus, while An. farauti was found in large numbers in the coastal areas of Mimika and Sarmi Regencies. Vector incrimination on Anopheles collected from HLCs and night indoor resting demonstrated that An. koliensis and An. punctulatus carried Plasmodium in Keerom, Jayapura, and Sarmi Regencies. Analysis of HLCs for the most common species revealed that the An. koliensis and An. punctulatus, bite indoors and outdoors at equal rates, while An. farauti predominantly bite outdoors. Larval surveillance demonstrated that most water bodies in and surrounding residential areas contained Anopheles larvae. This study demonstrated indoor and outdoor exposure to mosquito bites and gaps in protection, enabling exposure to infectious bites in all regencies. This explains why current malaria control efforts focusing on indoor protection have failed to substantially reduce malaria incidence in the region. Optimization of insecticide-treated bed nets (ITNs), as well as installment of mosquito screens in houses, may further reduce indoor transmission. For outdoor transmission, the use of community-centric approaches to reduce or eliminate larval sources within and surrounding the village through the guidance of locally stationed entomologists, along with Social and Behavior Change mediated health education towards the local adoption of mosquito protection tools during outdoor activities, may reduce malaria transmission.
Topics: Animals; Anopheles; Malaria; Humans; Mosquito Vectors; Indonesia; Larva; Endemic Diseases
PubMed: 38918533
DOI: 10.1038/s41598-024-64958-w -
PloS One 2024Mosquitoes (Diptera: Culicidae) are one of the most impactful pests to human society, both as a nuisance and a potential vector of human and animal pathogens. Mosquito...
Mosquitoes (Diptera: Culicidae) are one of the most impactful pests to human society, both as a nuisance and a potential vector of human and animal pathogens. Mosquito larvae develop in still aquatic environments. Eliminating these habitats near high human density or managing them to reduce the suitability for mosquitoes will reduce mosquito populations in these human environments and decrease the overall negative impact of mosquitoes on humans. One common source of standing water in urban and suburban environments is the water that pools in stormwater control measures. Previous studies have shown that some stormwater control measures generate large numbers of mosquitoes while others harbor none, and the reason for this difference remains unclear. Our study focuses on elucidating the factors that cause a stormwater control measure to be more or less suitable for mosquitoes. During the summers of 2021 and 2022, we collected and identified mosquito larvae from thirty stormwater control measures across central Ohio to assess variation in mosquito abundance and diversity among sites. Our goal was to determine if specific types of stormwater control measures (retention ponds, detention ponds, or constructed wetlands) harbored different abundances of mosquitoes or different community structures. We also assessed environmental parameters of these sites to elucidate their effects on mosquito abundance and diversity. Overall, we recorded the highest number of mosquito larvae and species in constructed wetlands. However, these sites were dominated by the innocuous species, Culex territans. Conversely, detention ponds held fewer mosquitoes but a higher proportion of known vector species, including Culex pipiens and Aedes vexans. The total number of mosquitoes across all sites was correlated with higher vegetation, more shade, lower water temperatures, and lower pH, suggesting stormwater control measures with these features may also be hotspots for mosquito proliferation.
Topics: Animals; Wetlands; Culicidae; Ponds; Ohio; Larva; Biodiversity; Mosquito Control; Ecosystem; Humans; Mosquito Vectors
PubMed: 38917214
DOI: 10.1371/journal.pone.0305399 -
Proceedings of the National Academy of... Jul 2024Controlling the principal African malaria vector, the mosquito , is considered essential to curtail malaria transmission. However, existing vector control technologies...
Controlling the principal African malaria vector, the mosquito , is considered essential to curtail malaria transmission. However, existing vector control technologies rely on insecticides, which are becoming increasingly ineffective. Sterile insect technique (SIT) is a powerful suppression approach that has successfully eradicated a number of insect pests, yet the toolkit lacks the requisite technologies for its implementation. SIT relies on iterative mass releases of nonbiting, nondriving, sterile males which seek out and mate with monandrous wild females. Once mated, females are permanently sterilized due to mating-induced refractoriness, which results in population suppression of the subsequent generation. However, sterilization by traditional methods renders males unfit, making the creation of precise genetic sterilization methods imperative. Here, we introduce a vector control technology termed precision-guided sterile insect technique (pgSIT), in for inducible, programmed male sterilization and female elimination for wide-scale use in SIT campaigns. Using a binary CRISPR strategy, we cross separate engineered Cas9 and gRNA strains to disrupt male-fertility and female-essential genes, yielding >99.5% male sterility and >99.9% female lethality in hybrid progeny. We demonstrate that these genetically sterilized males have good longevity, are able to induce sustained population suppression in cage trials, and are predicted to eliminate wild populations using mathematical models, making them ideal candidates for release. This work provides a valuable addition to the malaria genetic biocontrol toolkit, enabling scalable SIT-like confinable, species-specific, and safe suppression in the species.
Topics: Animals; Male; Anopheles; Mosquito Vectors; Malaria; Female; Mosquito Control; Infertility, Male; CRISPR-Cas Systems
PubMed: 38917000
DOI: 10.1073/pnas.2312456121 -
BioRxiv : the Preprint Server For... Jun 2024(or ) , the causative agent of Lyme disease, is a motile and invasive zoonotic pathogen, adept at navigating between its arthropod vector and mammalian host. While...
UNLABELLED
(or ) , the causative agent of Lyme disease, is a motile and invasive zoonotic pathogen, adept at navigating between its arthropod vector and mammalian host. While motility and chemotaxis are well established as essential for its enzootic cycle, the function of methyl-accepting chemotaxis proteins (MCPs) in the infectious cycle of remains unclear. In this study, we demonstrate that MCP5, one of the most abundant MCPs in , is differentially expressed in response to environmental signals as well as at different stages of the pathogen's enzootic cycle. Specifically, the expression of is regulated by the Hk1-Rrp1 and Rrp2-RpoN-RpoS pathways, which are critical for the spirochete's colonization of the tick vector and mammalian host, respectively. Infection experiments with an mutant revealed that spirochetes lacking MCP5 could not establish infections in either C3H/HeN mice or Severe Combined Immunodeficiency (SCID) mice, which are defective in adaptive immunity, indicating the essential role of MCP5 in mammalian infection. However, the mutant could establish infection and disseminate in NOD SCID Gamma (NSG) mice, which are deficient in both adaptive and most innate immune responses, suggesting a crucial role of MCP5 in evading host innate immunity. In the tick vector, the mutants survived feeding but failed to transmit to mice, highlighting the importance of MCP5 in transmission. Our findings reveal that MCP5, regulated by the Rrp1 and Rrp2 pathways, is critical for the establishment of infection in mammalian hosts by evading host innate immunity and is important for the transmission of spirochetes from ticks to mammalian hosts, underscoring its potential as a target for intervention strategies.
SUMMARY
Lyme disease is the most commonly reported arthropod-borne illness in the US, Europe, and Asia. The causative agent of Lyme disease, , is maintained in an enzootic cycle involving arthropod vectors ( ticks) and rodent mammalian hosts. Understanding how moves within this natural cycle is crucial for developing new strategies to combat Lyme disease. The complex nature of the enzootic cycle necessitates sensory-guided movement in response to environmental stimuli. possesses a unique and intricate chemotaxis signaling system, with methyl-accepting chemotaxis proteins (MCPs) at its core. These proteins are responsible for sensing environmental signals and guiding bacterial movement toward or away from stimuli. This study found that one of the MCPs, MCP5, is highly expressed and differentially regulated during the enzootic cycle by the Hk1-Rrp1 and Rrp2-RpoN-RpoS pathways. MCP5 is crucial for mammalian infection, aiding in immune evasion and transmission from ticks to mammals, providing a foundation for further research into 's navigation within its hosts.
PubMed: 38915556
DOI: 10.1101/2024.06.10.598185 -
Scientific Reports Jun 2024Pyrethroid bednets treated with the synergist piperonyl butoxide (PBO) offer the possibility of improved vector control in mosquito populations with metabolic...
LLIN Evaluation in Uganda Project (LLINEUP)-effects of a vector control trial on Plasmodium infection prevalence and genotypic markers of insecticide resistance in Anopheles vectors from 48 districts of Uganda.
Pyrethroid bednets treated with the synergist piperonyl butoxide (PBO) offer the possibility of improved vector control in mosquito populations with metabolic resistance. In 2017-2019, we conducted a large-scale, cluster-randomised trial (LLINEUP) to evaluate long-lasting insecticidal nets (LLINs) treated with a pyrethroid insecticide plus PBO (PBO LLINs), as compared to conventional, pyrethroid-only LLINs across 104 health sub-districts (HSDs) in Uganda. In LLINEUP, and similar trials in Tanzania, PBO LLINs were found to provide greater protection against malaria than conventional LLINs, reducing parasitaemia and vector density. In the LLINEUP trial, we conducted cross-sectional household entomological surveys at baseline and then every 6 months for two years, which we use here to investigate longitudinal changes in mosquito infection rate and genetic markers of resistance. Overall, 5395 female Anopheles mosquitoes were collected from 5046 households. The proportion of mosquitoes infected (PCR-positive) with Plasmodium falciparum did not change significantly over time, while infection with non-falciparum malaria decreased in An. gambiae s.s., but not An. funestus. The frequency of genetic markers associated with pyrethroid resistance increased significantly over time, but the rate of change was not different between the two LLIN types. The knock-down resistance (kdr) mutation Vgsc-995S declined over time as Vgsc-995F, the alternative resistance mutation at this codon, increased. Vgsc-995F appears to be spreading into Uganda. Distribution of LLINs in Uganda was previously found to be associated with reductions in parasite prevalence and vector density, but here we show that the proportion of infective mosquitoes remained stable across both PBO and non-PBO LLINs, suggesting that the potential for transmission persisted. The increased frequency of markers of pyrethroid resistance indicates that LLIN distribution favoured the evolution of resistance within local vectors and highlights the potential benefits of resistance management strategies.Trial registration: This study is registered with ISRCTN, ISRCTN17516395. Registered 14 February 2017, http://www.isrctn.com/ISRCTN17516395 .
Topics: Animals; Anopheles; Insecticide Resistance; Uganda; Mosquito Vectors; Insecticide-Treated Bednets; Mosquito Control; Humans; Pyrethrins; Insecticides; Malaria; Female; Plasmodium falciparum; Prevalence; Genetic Markers; Cross-Sectional Studies; Malaria, Falciparum; Piperonyl Butoxide; Genotype
PubMed: 38914669
DOI: 10.1038/s41598-024-65050-z -
Current Opinion in Insect Science Jun 2024Mosquito-borne diseases have a major impact on global human health. Biological agents that colonize the mosquito vector are increasingly explored as an intervention... (Review)
Review
Mosquito-borne diseases have a major impact on global human health. Biological agents that colonize the mosquito vector are increasingly explored as an intervention strategy to prevent vector-borne disease transmission. For instance, the release of mosquitoes carrying the endosymbiotic bacterium Wolbachia effectively reduced dengue virus incidence and disease. Insect-specific viruses are likewise considered as biocontrol agents against vector-borne diseases. While most studies focused on insect-specific viruses as an intervention against arthropod-borne viruses, we here consider whether mosquito-specific viruses may affect transmission of the malaria causing Plasmodium parasite by Anopheles mosquitoes. Although there is no direct experimental evidence addressing this question, we found that viral infections in dipteran insects activate some of the immune pathways that are antiparasitic in Anopheles. These findings suggest that indirect virus-parasite interactions could occur and that insect-specific viruses may modulate malaria transmission. Tripartite interactions between viruses, parasites, and Anopheles mosquitoes thus merit further investigation.
PubMed: 38908822
DOI: 10.1016/j.cois.2024.101222 -
Scientific Reports Jun 2024The applicability of the specific human IgG antibody response to Anopheles gambiae salivary Gland Protein-6 peptide 1 (gSG6-P1 salivary peptide) as a biomarker able to...
The applicability of the specific human IgG antibody response to Anopheles gambiae salivary Gland Protein-6 peptide 1 (gSG6-P1 salivary peptide) as a biomarker able to distinguish the level of exposure to mosquito bites according to seasonal variations has not yet been evaluated in Central African regions. The study aimed to provide the first reliable data on the IgG anti-gSG6-P1 response in rural area in Cameroon according to the dry- and rainy-season. Between May and December 2020, dry blood samples were collected from people living in the Bankeng village in the forest area of the Centre region of Cameroon. Malaria infection was determined by thick-blood smear microscopy and multiplex PCR. The level of IgG anti-gSG6-P1 response, was assessed by enzyme-linked immunosorbent assay. Anopheles density and aggressiveness were assessed using human landing catches. The prevalence of malaria infection remains significantly higher in the rainy season than in the dry season (77.57% vs 61.44%; p = 0.0001). The specific anti-gSG6-P1 IgG response could be detected in individuals exposed to few mosquito bites and showed inter-individual heterogeneity even when living in the same exposure area. In both seasons, the level of anti-gSG6-P1 IgG response was not significantly different between Plasmodium infected and non-infected individuals. Mosquito bites were more aggressive in the rainy season compared to the dry season (human biting rate-HBR of 15.05 b/p/n vs 1.5 b/p/n) where mosquito density was very low. Infected mosquitoes were found only during the rainy season (sporozoite rate = 10.63% and entomological inoculation rate-EIR = 1.42 ib/p/n). The level of IgG anti-gSG6-P1 response was significantly higher in the rainy season and correlated with HBR (p ˂ 0.0001). This study highlights the high heterogeneity of individual's exposure to the Anopheles gambiae s.l vector bites depending on the transmission season in the same area. These findings reinforce the usefulness of the anti-gSG6-P1 IgG response as an accurate immunological biomarker for detecting individual exposure to Anopheles gambiae s.l. bites during the low risk period of malaria transmission in rural areas and for the differentiating the level of exposure to mosquitoes.
Topics: Animals; Anopheles; Humans; Cameroon; Immunoglobulin G; Insect Bites and Stings; Female; Adult; Male; Salivary Proteins and Peptides; Rural Population; Seasons; Adolescent; Young Adult; Malaria; Middle Aged; Child; Mosquito Vectors; Child, Preschool; Insect Proteins
PubMed: 38906949
DOI: 10.1038/s41598-024-58337-8 -
Trials Jun 2024This trial is a parallel, two-arm, non-blinded cluster randomised controlled trial that is under way in Singapore, with the aim of measuring the efficacy of male...
BACKGROUND
This trial is a parallel, two-arm, non-blinded cluster randomised controlled trial that is under way in Singapore, with the aim of measuring the efficacy of male Wolbachia-infected Aedes aegypti deployments in reducing dengue incidence in an endemic setting with all four dengue serotypes in circulation. The trial commenced in July 2022 and is expected to conclude in September 2024. The original study protocol was published in December 2022. Here, we describe amendments that have been made to the study protocol since commencement of the trial.
METHODS
The key protocol amendments are (1) addition of an explicit definition of Wolbachia exposure for residents residing in intervention sites based on the duration of Wolbachia exposure at point of testing, (2) incorporation of a high-dimensional set of anthropogenic and environmental characteristics in the analysis plan to adjust for baseline risk factors of dengue transmission, and (3) addition of alternative statistical analyses for endpoints to control for post hoc imbalance in cluster-based environmental and anthropogenic characteristics.
DISCUSSION
The findings from this study will provide the first experimental evidence for the efficacy of releasing male-Wolbachia infected mosquitoes to reduce dengue incidence in a cluster-randomised controlled trial. The trial will conclude in 2024 and results will be reported shortly thereafter.
TRIAL REGISTRATION
ClinicalTrials.gov, identifier: NCT05505682. Registered on 16 August 2022. Retrospectively registered. Last updated 11 November 2023.
Topics: Dengue; Animals; Wolbachia; Singapore; Male; Aedes; Humans; Incidence; Mosquito Vectors; Randomized Controlled Trials as Topic; Mosquito Control; Female; Pest Control, Biological
PubMed: 38902790
DOI: 10.1186/s13063-024-08148-z -
BMC Public Health Jun 2024Aedes mosquitoes are the main vector of dengue infection, a global health threat affecting millions of people annually. Conventional prevention and control methods...
BACKGROUND
Aedes mosquitoes are the main vector of dengue infection, a global health threat affecting millions of people annually. Conventional prevention and control methods against dengue outbreaks have only achieved marginal success. Recognizing the complex issue at hand, a multilevel participatory approach is crucial. Thus, alternative strategies that involve community engagement are increasingly being considered and attempted. While community-based vector control programs have been conducted, sustaining behavioral changes among the population remains a challenge. This study aimed to identify the specific community needs in combating Aedes mosquitoes and dengue fever as a basis to guide the development of community-driven initiatives and foster a deeper sense of ownership in the fight against dengue.
METHODS
Between 1 August 2022 and 30 November 2022, we conducted a study in Hulu Langat district, Selangor, using a mixed-method design. All participants consented to the study, which comprised 27 participants (FGDs) and 15 participants (IDIs). The IDIs included two participants with a history of dengue fever, one community leader, one faith leader, seven local authorities, and four district health officers. Semi-structured interviews and discussions were performed among stakeholders and community members recruited via purposive and snowball sampling techniques. All interviews were audio-recorded before being analyzed using reflexive thematic analysis.
RESULTS
These results derived from qualitative data explored the perspectives and needs of communities in combating Aedes mosquitoes and dengue fever. Interviews were conducted with various stakeholders, including community members, leaders, and health officers. The study identified the necessity of decisive actions by authorities to address the impact of the dengue epidemic, the importance of community engagement through partnerships and participatory approaches, the potential benefits of incentives and rewards to enhance community participation, and the need for sustained community engagement and education, especially via the involvement of young people in prevention efforts. These findings provide valuable insights into the design of effective strategies against Aedes mosquitoes and dengue fever.
CONCLUSIONS
In short, there is an urgent need for a comprehensive approach involving multiple stakeholders in the fight against Aedes mosquitoes and dengue fever. The approach should incorporate efforts to raise awareness, provide practical resources, and foster community responsibility. The active involvement of teenagers as volunteers can contribute to long-term prevention efforts. Collaboration, resource allocation, and community engagement are crucial for effective dengue control and a healthier environment.
Topics: Humans; Aedes; Dengue; Animals; Female; Male; Adult; Mosquito Control; Community Participation; Urban Population; Middle Aged; Mosquito Vectors; Indonesia; Qualitative Research; Needs Assessment; Health Knowledge, Attitudes, Practice; Young Adult
PubMed: 38902692
DOI: 10.1186/s12889-024-18965-1 -
Scientific Reports Jun 2024Seal lice (Echinophthirius horridus) are bloodsucking ectoparasites of phocid seals and vectors of pathogens like the heartworm, Acanthocheilonema spirocauda. Grey and...
Seal lice (Echinophthirius horridus) are bloodsucking ectoparasites of phocid seals and vectors of pathogens like the heartworm, Acanthocheilonema spirocauda. Grey and harbour seal populations are recovering in German waters and wildlife health surveillance is crucial for wildlife conservation. A new, high effort sampling protocol for seal lice was applied for grey and harbour seals along the German North- and Baltic Sea coast. Freshly dead seals were systematically sampled within a health monitoring of stranded seals over 12 months. Prevalence, intensity and distribution patterns of seal lice were analysed. 58% of harbour seals (n = 71) and 70% of grey seals (n = 10) were infected with seal lice. A majority of harbour seals displayed mild levels of infection, while three were moderately and two were severely infected. The head was the preferred predilection site, indicating that E. horridus prefers body areas with frequent access to atmospheric oxygen. Nits and different developmental stages were recorded in all age classes in grey and harbour seals in all seasons. For the first time, copulating specimens of E. horridus were recorded on a dead harbour seal, highlighting that E. horridus reproduces throughout the year on seals of all age classes in German waters.
Topics: Animals; Prevalence; Seals, Earless; Phoca; Female; Male; Lice Infestations; Germany; Phthiraptera
PubMed: 38902289
DOI: 10.1038/s41598-024-64890-z