The importance of vector control for the control and elimination of vector-borne diseases

Strengthening resilience to emerging vector-borne diseases in Europe: lessons learnt from countries facing endemic transmission

Emerging vector-borne diseases (VBDs) are a major public health concern worldwide. Climate change, environmental degradation and globalisation have led to an expansion in the range of many vectors and an erosion of transmission barriers, increasing human exposure to new pathogens and the risk for emerging VBD outbreaks. Europe is potentially underprepared for the increasing threat of VBDs, due to attention and funding being diverted to other public health priorities. Proactive, rather than reactive, prevention and control approaches can greatly reduce the socio-economic toll of VBDs. Endemic countries globally have decades of experience in controlling VBDs, and Europe has much to learn from this knowledge. Here, we advocate for the expansion of transdisciplinary knowledge-sharing partnerships, to co-create proactive measures against VBDs. We present the experiences and expertise of our diverse international team and explore how an array of interventions can be applied and adapted to the European context.

The emergence of oropouche fever: A potential new threat?

Oropouche fever, caused by the Oropouche virus (OROV), has become a significant public health concern. Recent outbreaks highlight its increasing global spread, driven by environmental, social, and ecological factors. The disease presents clinical similarities to other arboviral infections, making accurate diagnosis essential for effective management and prevention. This article examines the epidemiological patterns of Oropouche fever, including its geographic distribution and outbreak drivers. It explores the clinical manifestations of the disease, focusing on common symptoms, complications such as fatal cases and fetal abnormalities, and the necessity of differential diagnosis. The pathophysiology of OROV infection is analyzed, detailing viral entry mechanisms, immune responses, and the role of vectors in transmission. Additionally, we assess diagnostic challenges, comparing serological and molecular methods while identifying their limitations. Therapeutic strategies are also reviewed, including symptomatic treatments and potential antiviral candidates. Findings indicate that OROV infections mimic other arboviral diseases, complicating clinical diagnosis. Current diagnostic tools have limitations in accuracy and accessibility, particularly in resource-limited settings. Symptomatic treatment remains the primary approach, as no specific antiviral therapies or vaccines exist. The study identifies gaps in diagnostic development, vaccine research, and public health surveillance. Oropouche fever threatens global health, necessitating improved surveillance, diagnostic tools, and targeted research efforts. Enhancing epidemiological studies and developing effective vaccines will mitigate its impact. Strengthening public health strategies can help control the spread of OROV and reduce its burden on affected populations.

Imaging the lifecycle of Microsporidia sp. MB in Anopheles coluzzii from western Burkina Faso reveals octosporogony

A newly discovered microsporidian, Microsporidia sp. MB (MB), was recently found to block Plasmodium falciparum transmission in Anopheles arabiensis mosquitoes from Kenya. Here, we describe the lifecycle of the first laboratory colony of Anopheles coluzzii with MB, originating from western Burkina Faso. The lifecycle of MB was explored using fluorescent in situ hybridization and confocal microscopy, facilitated by the development of optimized protocols to produce histological sections of whole adult, larval, and embryo tissues. As in An. arabiensis, transmission appears to be predominantly vertical, with MB highly localized to the ovaries across multiple lifecycle stages. MB was sparsely distributed within the majority of developing oocytes in the gravid female. After oviposition, in the majority of embryos, MB relocated to the developing gonad at the onset of tissue differentiation, suggesting a highly specialized adaptation to host tissues. Sporogony was identified for the first time in a proportion of developing oocytes and in embryos post-oviposition. Microsporidian spore characteristics were subsequently confirmed with electron microscopy. Identification of MB sporogony in eggs suggests there are alternative horizontal routes of transmission which could play an important role in developing MB as a malaria control strategy.

IMPORTANCE

Malaria in West Africa, caused by Plasmodium falciparum infection and spread by anopheline mosquitoes, is responsible for hundreds of thousands of deaths annually and resulted in over 120 million cases in 2022 . The transmission-blocking effect of Microsporidia sp. MB (MB) suggests its potential as an agent for combating the spread of malaria. Understanding the routes of transmission and their effect on MB in mosquito populations is crucial for its development as a control tool. The identification of MB spores reveals the potential for another avenue of transmission beyond the vertical transmission from female to offspring. Spores could also have the potential for alternative MB dissemination methods, alongside or instead of adult mosquito releases.

Climate-responsive vector control strategies for Aedes albopictus

BACKGROUND

The rise in mosquito-borne diseases such as dengue, Zika, and chikungunya, exacerbated by the ever-expanding habitats of Aedes albopictus, poses a significant public health risk. Even marginal improvements in vector control efficacy can be crucial in mitigating these risks.

METHODS

In this study, we employed a metapopulation model to simulate Ae. albopictus population dynamics and dispersal, optimizing the timing and spatial allocation of larvicidal treatments.

RESULTS

Simulations revealed that larvicide treatments are most effective when applied preventively, early in the mosquito season, particularly under conditions of lower-than-average cumulative rainfall and, to a minor extent, colder-than-average temperatures, as these conditions limit larvae proliferation. We found that breeding site characteristics, particularly surface area and maximum water holding capacity, are critical in determining optimal treatment allocation in scarce-resource scenarios. However, a cost-effectiveness trade-off exists, as larger breeding sites offer more substantial reductions in mosquito populations but also demand higher larvicide dosages. Spatial factors such as breeding site distribution had minimal impact on treatment efficacy, possibly due to the high mobility range of adult mosquitoes compared with the size of the study area.

CONCLUSIONS

Our results highlight the superior efficiency of the optimized approach in comparison with routine vector control strategies, especially when resources are limited, offering a more effective use of larvicide in controlling mosquito populations. This study demonstrates that vector control strategies for Ae. albopictus can be significantly enhanced by considering climatic variables and breeding site characteristics in treatment planning. This research provides a framework for developing cost-effective and flexible mosquito control programs that can adapt to environmental conditions, potentially improving public health outcomes by reducing the transmission risk of mosquito-borne diseases.

Incorporating adult age into mosquito population models: Implications for predicting abundances in changing climates

Mosquito-borne diseases (MBDs) pose increasing threats under future climate change scenarios and an understanding of mosquito population dynamics is pivotal to predicting future risk of MBDs. Most models that describe mosquito population dynamics often assume that adult life-history is independent of adult age and yet mosquito senescence is known to affect mosquito mortality, fecundity and other key biological traits. Despite this, little is known about the effects of adult age at the level of the mosquito population, especially under varying temperature scenarios. We develop a stage-structured delayed differential equations (DDEs) model incorporating the effects of the abiotic environment and adult age to shed light on the complex interactions between age, temperature, and mosquito population dynamics. Taking Culex pipiens, a major vector of West Nile Virus, as our study species our results show that failing to consider mosquito senescence can lead to underestimates of future mosquito abundances predicted under climate change scenarios. We also find that the age-dependent mechanisms combined with the effects of density-dependent mortality on the immature stages can result in mosquito abundances decreasing at extreme temperatures. With our work, we underscore the need for more studies to consider the effects of mosquito age. Not accounting for senescence can compromise the accuracy of abundance estimates and has implications for predicting the risk of future MBD outbreaks.

Functional characterization of vitellogenin unveils novel roles in RHBP uptake and lifespan regulation in the insect vector Rhodnius prolixus

In insects, vitellogenesis plays a critical role in providing the energy reserves needed for embryonic development as it ensures the accumulation of yolk in the oocytes. Vitellogenin (Vg), the precursor to vitellin (Vt), is primarily synthesized in the fat body of females and transported to the oocytes via receptor-mediated endocytosis. In Rhodnius prolixus, a key vector of Chagas disease, two Vg genes, Vg1 and Vg2, were characterized. These genes share 65 % amino acid identity and present the conserved Vitellogenin_N, DUF1943, and VWD domains typical of Vg proteins across various species. We found that Vg1 is expressed at significantly higher levels than Vg2 in adult females. Still, the expression of both isoforms was also detected in organs such as the flight muscle, midgut, and ovary, as well as in males and nymphs. RNAi-mediated knockdown of Vg1 and Vg2 in adult females resulted in the production of yolk-depleted eggs with drastically reduced levels of Vg and RHBP, the second most import yolk protein in this species. Despite regular oviposition rates, most of these eggs were inviable, highlighting the essential role of Vg and RHBP in embryo development. Although Vg expression was detected in adult males, the mating of Vg-knockdown males with wild-type females did not impact oviposition or egg viability, indicating that male Vg is not crucial for oogenesis in this species. Interestingly, Vg knockdown increased lifespan for both males and females, suggesting additional physiological functions beyond reproduction. These findings reveal the importance of Vg in oogenesis and embryonic development in R. prolixus while also suggesting potential non-reproductive roles of Vg in adult insect physiology.

Thinking outside the box: Citizen science to monitor phlebotomine sand flies in Spain

The Flebocollect project is a citizen science (CS) initiative in which a diverse group of participants, mainly high-school students, were requested to monitor sand flies (fm. Psychodidae; sfm. Phlebotominae), vectors of Leishmania parasites and Phlebovirus. The project generated entomological data that was then used to prepare an online free-access sand fly monitoring map providing information about the distribution areas of this vector group in Spain. This initiative contributes to our understanding of sand fly dynamics and thus of the risk of disease transmission, while promoting education and public health engagement in line with Sustainable Development Goals (SDGs). We were also able to confirm the potential of CS for advancing research and strengthening sustainable vector surveillance, thus meeting the demands of The Global Vector Control Response 2017-2030 program. Didactic impact was analyzed through a test distributed to the participants before and after the educational program (pre- and post-test respectively) to assess the potential of CS as a learning tool and to promote a better attitude towards science. The project's success in Spain demonstrates that similar citizen science initiatives could be replicated elsewhere, provided they receive funding through dedicated scientific outreach budgets and are designed with long-term sustainability in mind.

Assessing Wolbachia circulation in wild populations of phlebotomine sand flies from Spain and Morocco: implications for control of leishmaniasis

BACKGROUND

Vector-borne diseases such as leishmaniasis exert a huge burden of morbidity and mortality that are mainly controlled through vector control. The increasing threat of insecticide-resistant vectors entails incorporating more vector control interventions to eliminate these diseases. Introduction of Wolbachia into wild vector populations has been suggested as a potential vector control measure that would require extensive regional knowledge. The aim of this work is to estimate the prevalence of Wolbachia infection and monitor circulating strains in wild sand fly populations from Spain and Morocco, two countries where leishmaniasis is endemic.

METHODS

Wolbachia was detected using polymerase chain reaction (PCR). Haplotype diversity was performed by sequencing, and phylogenetic relationships were then established. In silico prediction of the Wolbachia surface protein (WSP) structures was performed. To investigate the relationship between epidemiological variables and the presence of Wolbachia, regression analyses were employed.

RESULTS

Wolbachia was detected in 45.8% of the specimens tested (319/697), and similar infection rates were found (P = 0.92) in males (46.1%; 94/204) and females (45.6%; 225/493). Differences in infection were detected among Spanish sand fly species (P < 0.001), being higher for Phlebotomus papatasi (35/52) and Phlebotomus perniciosus (239/384). No infected Phlebotomus sergenti specimens were found in Spain, whereas two different Wolbachia haplotypes were detected in P. sergenti sand flies from Morocco. No significant differences were found between sex, species, or capture sites in specimens captured in Morocco (P > 0.05). Five Wolbachia haplotypes distributed in the known A and B supergroups were identified. Structural analysis showed a nine-amino acid insertion in the fourth loop of a Wolbachia haplotype found in P. sergenti specimens from El Borouj (Morocco).

CONCLUSIONS

We confirmed the circulation of different Wolbachia strains in all sand fly species investigated. All L. infantum proven or suspected vectors shared the same, or a closely related, Wolbachia haplotype. The haplotype bearing the loop insertion was found in the locality undergoing an anthroponotic cutaneous leishmaniasis outbreak. These extracellular loops might have some role in enhancing or inhibiting the development of Leishmania and other pathogens in sand flies. These findings are very promising and highlight the need to further investigate the tripartite interactions between Wolbachia strain, Leishmania species, and sand fly species/lineage.

Targeting the Xylella fastidiosa spittlebug vector Neophilaenus campestris in the olive cover crops with the entomopathogenic fungus Metarhizium brunneum

Introduction

Neophilaenus campestris (Fallén) (Hemiptera: Aphrophoridae) is among the most abundant, highly dispersible, and widely distributed Xylella fastidiosa Wells (Xanthomonadales: Xanthomonadaceae) vectors to olive tree in Europe, with emphasis in Andalucía. The development of efficient and environmentally friendly vector management strategies is greatly needed. Entomopathogenic ascomycetes are among the few alternatives for the microbial control of pierce-sucking spittlebugs due to their unique contact mode and ability to endophytically colonize crops. These characteristics allow for several strategic uses aimed at reducing vector populations and/or their disease transmission potential. This study included a two-year field experiment to evaluate the Metarhizium brunneum Petch. (Ascomycota: Hypocreales) strain EAMa 01/58-Su sprayed onto N. campestris population naturally present in the olive grove cover in Cordoba (Spain).

Methods

Experiments were conducted in early spring, and efficacy was evaluated using the Henderson-Tilton formula, as well as by analyzing changes in the relative population density of both nymphs and adults.

Results and discussion

The fungus was detected in the soil and endophytically in the natural cover throughout the 8 days monitoring period, in which the fungal treatment significantly reduced both the nymph and the adult populations. Notably, the efficacy of the fungal treatment was 100.0% and 85.0% for foams and adults in 2023, and 62.5% and 72.0% for foams and adults in 2024, respectively. Results indicate a significant reduction in the population density of both vector developmental stages, highlighting the potential of this fungal strain for managing X. fastidiosa vectors in olive cover crops.

Collaborative engagement with vector control stakeholders is key to enhance the utility of vector-borne disease models

BACKGROUND

Despite the growing complexity, computational power, and mapping capacity incorporated into vector-borne disease models, they still do not fully elucidate the role of environmental, demographic, socioeconomic, or other drivers, and rarely directly inform vector control efforts. To understand how we can improve the utility of vector-borne disease models for vector control activities, we interviewed vector control agents from the United States (USA) and the European Union.

METHODS

Between July and December 2023, in-depth interviews were held using a geographically targeted convenience sample with 26 individuals from organizations involved in vector control operations: 12 in the USA and 14 in the EU. We used both deductive and inductive coding of transcribed interviews to identify themes with the goal of understanding barriers to model use and uptake.

RESULTS

Despite the recognition that models could be useful, few interviewees reported that models informed surveillance and control activities, citing a mismatch in spatial and temporal scale between model outputs and operational decisions or a general lack of accessibility. Interviewees reported relying on experienced field experts and legacy protocols. Despite these critiques, there is belief that models can support operational decision-making.

CONCLUSIONS

The disconnect between models and users can be improved by allowing time and resources to build collaborative relationships, by acknowledging the knowledge all members bring, and by ensuring clear communication and mutual respect. Modelers must shift their focus by aligning vector-borne disease models with operational needs.

Contribution of Nilaparvata lugens Nicotinic Acetylcholine Receptor Subunits Toward Triflumezopyrim and Neonicotinoid Susceptibility

Nicotinic acetylcholine receptors (nAChRs) are the molecular targets of some important insecticides including triflumezopyrim and neonicotinoids. However, our understanding of insect nAChR pharmacology and the specific nAChR subunits targeted by these insecticides remains limited. Here, we cloned 11 nAChR subunit genes, comprising Nlα1 to Nlα8, Nlα10, Nlβ1 and Nlβ3, from Nilaparvata lugens, a highly damaging insect pest of rice crops worldwide. Analysis of the expression of these genes in different tissues of N. lugens by qPCR analysis identified the brain as the primary site of expression. Knock down of the expression of Nlα1, Nlα2, Nlα8 and Nlβ1 using RNAi reduced N. lugens sensitivity to triflumezopyrim, suggesting these genes encode potential target subunits for triflumezopyrim. Knock out of Nlα2 and Nlα8 nAChR subunits by CRISPR/Cas9 genome editing showed that their deletion significantly reduced the toxicity of triflumezopyrim toward N. lugens. Furthermore, the deletion of Nlα2 also increased N. lugens resistance to imidacloprid and dinotefuran. However, numerous attempts revealed that the Nlβ1 knockout was nonviable. In vitro expression of receptors composed of Drosophila homologous subunits showed that this all-insect nAChR was inhibited by nanomolar concentrations of triflumezopyrim. The present findings identify specific nAChR subunits that are important both as targets for monitoring resistance-associated mutations and as subjects for molecular studies aimed at developing novel insecticides targeting these essential ion channels.

Evaluation of mycoparasitic Trichoderma atroviride and entomopathogenic Aspergillus niger as potential bioinsecticides against the dengue vector, Aedes aegypti

Introduction

Over the past three decades, dengue disease incidence has significantly increased worldwide, creating serious public health concerns. The principal mosquito vector, Aedes aegypti, exhibits resistance to commonly used insecticides, reducing the efficacy of vector control measures. Thus, the necessity for alternate strategies is critical. Using bioinsecticides such as entomopathogenic fungi (EPF) is one such strategy. This study details the evaluation of mycoparasitic Trichoderma atroviride and entomopathogenic Aspergillus niger against pyrethroid-resistant and pyrethroid-susceptible Ae. aegypti populations.

Materials and methods

Molecular identification of the isolated entomopathogenic fungal strains was done using ITS-rDNA sequence data. Larvicidal and adulticidal assays were performed using different spore concentrations of fungal species. Pupal emergence was assessed from the survived larvae of larvicidal assays.

Results

Larvicidal assays revealed the highest mortality of 60% for T. atroviride after 9 days of exposure when compared with the highest mortality of 52% for A. niger after 6 days of exposure. No significant difference was observed between the pyrethroid-resistant and pyrethroid-susceptible mosquito colonies, suggesting a lack of connection between prior resistance status and EPF pathogenicity. No pupal mortality was observed, although pupal duration was prolonged. Both EPF strains exhibited 100% mortality in adulticidal assays, signifying the potential use of the two fungal species as adulticides.

Conclusion

However, further studies are needed to understand the biology of EPF, its mechanism of action, the mosquito immune pathways activated, and the effect on non-target organisms. The findings have implications for the possible use of A. niger and T. atroviride as potential bioinsecticides against the control of Ae. aegypti.

Curcumin Microcapsule Formulations for Prolong Persistence in the Photodynamic Inactivation of Aedes aegypti Larvae

Background: Viral diseases including dengue, zika, chikungunya, and yellow fever remain a significant public health challenge, primarily due to the increasing resistance of these vectors, the Aedes aegypti mosquito, to conventional control methods. Objectives: Herein, a microencapsulated curcumin formulation was developed and characterized using spray-drying technology, with D-mannitol and starch as encapsulating agents. After microencapsulation, photolarvicidal tablet formulations (Formulated Curcumin Tablets-FCT) were prepared, varying the proportions of starch and pectin: FCT1 (60% starch), FCT2 (35% pectin and 25% starch), and FCT3 (42.5% pectin and 17.5% starch), while maintaining 10% curcumin and 30% D-mannitol in all formulations. The main goal was to enhance the stability and efficacy of curcumin as a photolarvicidal agent. Methods: The formulation was characterized by UV-Vis spectroscopy, confocal microscopy, thermal analysis (TG and DSC), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and photodegradation assays under fluorescent light. Results: The photodynamic inactivation (PDI) of Ae. aegypti larvae was evaluated under white, fluorescent light exposure, and the formulation exhibited a significantly enhanced larvicidal activity compared to free curcumin, with a 57-fold reduction in LC50 (LC50-24h = 0.27 mg/L). Additionally, the most effective formulation, FCT2, maintained its residual activity for 27 days, reinforcing that curcumin microencapsulation, combined with PDI, can extend vector control. Release studies under different pH conditions confirmed a controlled release mechanism, favoring environmental stability. Conclusions: The results indicate that microencapsulated curcumin has great potential as a sustainable photoinsecticidal agent, offering stability, efficacy, and a promising alternative for managing Ae. aegypti larval populations.

Comparative larvicidal, pupicidal, adulticidal activity of Artemisia nilagirica (C.B. Cl) pamp extract in controlling Culex quinquefasciatus, Anopheles stephensi, Aedes aegypti and Aedesalbopictus

Vector-borne diseases cause increase in burden, poverty, social liability and death all over the world. Mosquitoes serve as the vector for malaria, dengue, filariasis, yellow fever and also play a major role in transmission of chikungunya and Zika virus. The development of mosquitocidal resistance and associated health problems with the use of synthetic insecticides, have paved the way to control mosquito population by using plant-based botanicals. This study was carried out to evaluate the larvicidal, pupicidal and adulticidal properties of six solvent extracts of Artemisia nilagirica (C.B.Cl) against four infectious vector mosquitoes Anopheles stephensi, Aedes aegypti, Aedes albopictus and Culex quinquefasciatus, by assessing LC50 and LC90 mortality values. Among all six leaf solvent extracts, chloroform extract had higher toxicity (LC50 = 127.27 ppm and LC90 = 544.45 ppm) against fourth instar larva of C. quinquefasciatus and aqueous extract had lowest lethal effects (LC50 = 583.33 ppm and LC90 = 927.27 ppm) against fourth instar larva of A. aegypti. Moderate results were found in n-hexane, petroleum ether, methanol and ethanol plant extracts. Phytochemical analysis by GC-MS method confirms presence of significant 12 bioactive compounds like Bi-cyclo (3.1.1) heptanes-2, 4, 6 trimethyl, 3, 7, 11, 15- Tetramethyl-1.2 hexadecan-1-ol, Thiophene, Tetrahydro-2-methyl 1,3 propane diamine and camphor, which were responsible for insecticidal activity. Altogether, current study would serve as an initial step towards replacement of synthetic insecticides to plant-based bio-pesticide against dreadful vector mosquitoes in future.

Cross-species immune activation and immunobiotics: a new frontier in vector-borne pathogen control

The persistent global burden of vector-borne diseases (VBDs) needs innovative control strategies, as traditional methods are compromised by acaricides and drug resistance and variable vaccine efficacy. We propose a dual-action strategy using cross-species immune activation: human microbiota triggers the production of natural antibodies that directly target pathogens in the host and modulate vector immunity by interacting with vector microbiota. The human microbiota also modulates cytokine responses, enhancing immune defenses in both host and vector. These mechanisms can be further optimized by identifying immunobiotics - specific gut microbes that stimulate protective immune responses against VBDs. This approach offers a sustainable framework to bridge the gap between host and vector immunity, introducing a novel method to combat VBDs.

Diel modulation of perireceptor activity influences olfactory sensitivity in diurnal and nocturnal mosquitoes

Olfaction and diel-circadian rhythm regulate different behaviors, including host-seeking, feeding, and locomotion, in mosquitoes that are important for their capacity to transmit disease. Diel-rhythmic changes of the odorant-binding proteins (OBPs) in olfactory organs are primarily accountable for olfactory rhythmicity. To better understand the molecular rhythm regulating nocturnal and diurnal behaviors in mosquitoes, we performed a comparative RNA-sequencing study of the peripheral olfactory and brain tissues of female Anopheles culicifacies and Aedes aegypti. Data analysis revealed a significant upregulation of genes encoding: OBPs and xenobiotic-metabolizing enzymes including Cytochrome P450 (CYP450) during photophase in Aedes aegypti and the dusk-transition phase in Anopheles culicifacies, hypothesizing their possible function in the regulation of perireceptor events and olfactory sensitivity. RNA interference studies and application of CYP450 inhibitors, coupled with electroantennographic recordings with Anopheles gambiae and Aedes aegypti, established that CYP450 plays a role in odorant detection and antennal sensitivity. Furthermore, brain tissue transcriptome and RNAi-mediated knockdown revealed that daily temporal modulation of neuronal serine proteases may have a crucial function in olfactory signal transmission, thereby affecting olfactory sensitivity. These findings provide a rationale to further explore the species-specific rhythmic expression pattern of the neuro-olfactory encoded molecular factors, which could pave the way to develop and implement successful mosquito control methods.

Resistance status of Aedes mosquitoes as dengue vectors and the potential of plant larvicides from Indonesia for biological control: A narrative review

Dengue fever remains a major public health threat in Indonesia, exacerbated by rising insecticide resistance in Aedes aegypti. Strategies relying on chemical insecticides, while initially effective, have led to widespread resistance in mosquito populations. This resistance is particularly pronounced in areas such as Java, where the extensive use of insecticides, including organophosphates and pyrethroids, has been documented. To address this challenge, one promising alternative is the utilization of biolarvicides derived from local Indonesian plant materials. Biolarvicides are environmentally friendly, safe, and have the potential to mitigate the adverse impacts associated with chemical insecticides. Numerous studies have explored the larvicidal properties of indigenous plants native to Indonesia, demonstrating their efficacy against A. aegypti. The aim of this study was to examine insecticide resistance in Aedes mosquitoes across Indonesia, highlighting geographical variations and underexplored regions, and exploring plant- based biolarvicides as sustainable alternatives. Biolarvicides derived from native Indonesian plants could be eco-friendly alternative for dengue vector management. Their integration into existing control strategies could significantly enhance efforts to control dengue while reducing the environmental and health risks posed by chemical insecticides.

Urban Aedes aegypti suitability indicators: a study in Rio de Janeiro, Brazil

BACKGROUND

Controlling Aedes aegypti stands as the primary strategy in curtailing the global threat of vector-borne viral infections such as dengue fever, which is responsible for around 400 million infections and 40 000 fatalities annually. Effective interventions require a precise understanding of Ae aegypti spatiotemporal distribution and behaviour, particularly in urban settings where most infections occur. However, conventionally applied sample-based entomological surveillance systems often fail to capture the high spatial variability of Ae aegypti that can arise from heterogeneous urban landscapes and restricted Aedes flight range.

METHODS

In this study, we aimed to address the challenge of capturing the spatial variability of Ae aegypti by leveraging emerging geospatial big data, including openly available satellite and street view imagery, to locate common Ae aegypti breeding habitats. These data enabled us to infer the seasonal suitability for Ae aegypti eggs and larvae at a spatial resolution of 200 m within the municipality of Rio de Janeiro, Brazil.

FINDINGS

The proposed microhabitat and macrohabitat indicators for immature Ae aegypti explained the distribution of Ae aegypti ovitrap egg counts by up to 72% (95% CI 70-74) and larval counts by up to 74% (72-76). Spatiotemporal interpolations of ovitrap counts, using suitability indicators, provided high-resolution insights into the spatial variability of urban immature Ae aegypti that could not be captured with sample-based surveillance techniques alone.

INTERPRETATION

The potential of the proposed method lies in synergising entomological field measurements with digital indicators on urban landscape to guide vector control and address the prevailing spread of Ae aegypti-transmitted viruses. Estimating Ae aegypti distributions considering habitat size is particularly important for targeting novel vector control interventions such as Wolbachia.

FUNDING

German Research Foundation and Austrian Science Fund.

Dietary L-3,4-dihydroxyphenylalanine (L-DOPA) augments cuticular melanization in Anopheles mosquitos while reducing their lifespan and malaria parasite burden

L-3,4-dihydroxyphenylalanine (L-DOPA), a naturally occurring tyrosine derivative, is prevalent in environments that include mosquito habitats, potentially serving as part of their diet. Given its role as a precursor for melanin synthesis we investigate the effect of dietary L-DOPA on mosquito physiology and immunity to Plasmodium falciparum and Cryptococcus neoformans infection. Dietary L-DOPA is incorporated into mosquito melanin via a non-canonical pathway and has a profound transcriptional effect associated with enhanced immunity, increased pigmentation, and reduced lifespan. Increased melanization results in an enhanced capacity to absorb electromagnetic radiation that affects mosquito temperatures. Bacteria in the mosquito microbiome act as sources of dopamine, a substrate for melanization. Our results illustrate how an environmentally abundant amino acid analogue can affect mosquito physiology and suggest its potential usefulness as an environmentally friendly vector control agent to reduce malaria transmission, warranting further research and field studies.

Identification and molecular characterization of Dirofilaria sp. "hongkongensis" (Rhabditida: Onchocercidae) in wild-caught mosquitoes (Diptera: Culicidae): first report from India

Dirofilariasis is a globally significant emerging-zoonotic-disease caused by nematode parasites belonging to the genus Dirofilaria (Rhabditida: Onchocercidae) and is transmitted by mosquitoes (Diptera: Culicidae) of the Culicidae family. A recent study on molecular prevalence of Dirofilaria sp. "hongkongensis" To, 2012 (nomen nudum) among the dog population in Kerala indicated a high infection rate. However, no data are currently available on the vectors involved in the transmission of this disease. In this study, an entomological survey was conducted to detect natural infection and to characterize the Dirofilaria parasite from Kani tribal settlements in Thiruvananthapuram, India. A total of 356 mosquitoes were collected, morphologically identified, and analyzed for natural infection of Dirofilaria from 4 different villages in the study area. The species composition of the collected mosquito specimens comprised 10 species belonging to 6 genera, namely Anopheles, Aedes, Armigeres, Culex, Uranotaenia, and Heizmannia. Aedes albopictus (Skuse, 1895) was found to be the predominant species, followed by Armigeres subalbatus Coquillett, 1898. Out of these, 200 female mosquitoes were grouped by species into 31 pools, for genomic DNA extraction. Detection of the nematode parasite was performed using nematode-specific primers via conventional PCR, and the species was subsequently confirmed by sanger sequencing. Natural-infection of Dirofilaria sp. "hongkongensis" was identified in Ae. albopictus and Ar. subalbatus, with a minimum infection rate of 17.6% and 13.3%, respectively. This study represents the first report of natural-infection of Dirofilaria sp. among field-collected mosquitoes in India. These findings underscore the need for robust entomological-surveillance system to prevent potential future outbreaks.

Modeling Intraday Aedes-human exposure dynamics enhances dengue risk prediction

Cities are the hot spots for global dengue transmission. The increasing availability of human movement data obtained from mobile devices presents a substantial opportunity to address this prevailing public health challenge. Leveraging mobile phone data to guide vector control can be relevant for numerous mosquito-borne diseases, where the influence of human commuting patterns impacts not only the dissemination of pathogens but also the daytime exposure to vectors. This study utilizes hourly mobile phone records of approximately 3 million urban residents and daily dengue case counts at the address level, spanning 8 years (2015-2022), to evaluate the importance of modeling human-mosquito interactions at an hourly resolution in elucidating sub-neighborhood dengue occurrence in the municipality of Rio de Janeiro. The findings of this urban study demonstrate that integrating knowledge of Aedes biting behavior with human movement patterns can significantly improve inferences on urban dengue occurrence. The inclusion of spatial eigenvectors and vulnerability indicators such as healthcare access, urban centrality measures, and estimates for immunity as predictors, allowed a further fine-tuning of the spatial model. The proposed concept enabled the explanation of 77% of the deviance in sub-neighborhood DENV infections. The transfer of these results to optimize vector control in urban settings bears significant epidemiological implications, presumably leading to lower infection rates of Aedes-borne diseases in the future. It highlights how increasingly collected human movement patterns can be utilized to locate zones of potential DENV transmission, identified not only by mosquito abundance but also connectivity to high incidence areas considering Aedes peak biting hours. These findings hold particular significance given the ongoing projection of global dengue incidence and urban sprawl.

Investigating seasonal disease emergence and extinction in stochastic epidemic models

Seasonal disease outbreaks are common in many infectious diseases such as seasonal influenza, Zika, dengue fever, Lyme disease, malaria, and cholera. Seasonal outbreaks are often due to weather patterns affecting pathogens or disease-carrying vectors or by social behavior. We investigate disease emergence and extinction in seasonal stochastic epidemic models. Specifically, we study disease emergence through seasonally varying parameters for transmission, recovery, and vector births and deaths in time-nonhomogeneous Markov chains for SIR, SEIR, and vector-host systems. A branching process approximation of the Markov chain is used to estimate the seasonal probabilities of disease extinction. Several disease outcome measures are used to compare the dynamics in seasonal and constant environments. Numerical investigations illustrate and confirm previous results derived from stochastic epidemic models. Seasonal environments often result in lower probabilities of disease emergence and smaller values of the basic reproduction number than in constant environments, and the time of peak emergence generally precedes the peak time of the seasonal driver. We identify some new results when both transmission and recovery vary seasonally. If the relative amplitude of the recovery exceeds that of transmission or if the periodicity is not synchronized in time, lower average probabilities of disease emergence occur in a constant environment than in a seasonal environment. We also investigate the timing of vector control. This investigation provides new methods and outcome measures to study seasonal infectious disease dynamics and offers new insights into the timing of prevention and control.

Advances in the Epidemiology, Pathogenesis, Diagnostic Methods, and Vaccine Development of Dengue Fever: A Comprehensive Review

Dengue fever (DF) is a common mosquito-borne viral infection caused by any of the four dengue virus (DENV) serotypes. In recent years, the global incidence of DF has risen rapidly, which has widely threatened the health of millions of people in the United States, Southeast Asia, and the Western Pacific. The challenges for the prevention and control of DENV infection have become increasingly severe. Over the years, advances in the area of DF research have been continuously updating. In this review, we provide an updated and more in-depth overview of dengue epidemiology and pathogenesis, along with recent progress in diagnostic approaches (including methods to address cross-reactivity with other flaviviruses) and an expanded discussion of current dengue vaccine development, such as CYD-TDV (Dengvaxia), TV003/TV005, and the new TAK-003. This comprehensive perspective aims to offer references for the prevention, clinical diagnosis, and control of the disease.

Leishmaniasis in deployed military populations: A systematic review and meta-analysis

Leishmaniasis affects military personnel deployed to endemic areas following exposure to sand flies infected with the protozoa Leishmania. This systematic review and meta-analysis of data specific to military populations aims to identify knowledge gaps to mitigate sand fly exposure and Leishmania transmission during deployments. The review was registered on PROSPERO (CRD42023463687). Random-effects meta-analyses and narrative synthesis were performed. Thirty-six studies were included, most of which reported on cutaneous leishmaniasis (CL), showing a mean cumulative incidence of 10% (95% CI: 5-16), suggesting higher rates in the Eastern Mediterranean region (14% [95% CI: 12-16]) compared to the African region (8%) and American region (9%). Asymptomatic Leishmania infection had a cumulative incidence of 11% (95% CI: 6-17), with higher rates in Eastern Mediterranean countries (20% [95% CI: 14-25]). Diagnosis involved parasitological, serological, and molecular methods, with L. (L) mexicana and L. (V.) braziliensis identified as the predominant CL pathogens in deployed troops in the Americas. Visceral leishmaniasis cases were less frequent, all reported from the Eastern Mediterranean and associated with the Leishmania donovani/infantum complex; whereas CL cases in the Old World were due predominantly to L. major and L. tropica. Regular use of long-lasting insecticidal nets to mitigate sand fly exposure demonstrated high potential effectiveness than other reported personal protective measures (PPMs) which yielded mixed or inconclusive results. In summary, the systematic review revealed the substantial variability between study designs and statistical integrity. There is need for more consistent and robustly designed studies including well-define controls and replication. Future studies would be advised to explore the long-term effectiveness and practicality of PPMs, both individually and in combination, across diverse deployment settings.

Exploring endosymbionts and pathogens in Rhipicephalus sanguineus and Ctenocephalides felis felis with Oxford Nanopore Technology

Fleas and ticks play a crucial role in public health as vectors of multiple diseases affecting humans and animals. Several rickettsial pathogens and endosymbionts are transmitted by fleas and ticks. Therefore, understanding this group of microorganisms is essential for fully grasping the spectrum of pathogens transmitted by vectors and the interactions between endosymbiotic microorganisms and their hosts. This study evaluated the presence and diversity of Rickettsiales species in fleas and ticks collected from the Santander department in Colombia. For the methodology a 16S gene amplification approach through Oxford Nanopore sequencing technologies in Rhipicephalus sanguineus and Ctenocephalides felis felis was used. Our findings revealed the presence of multiple pathogenic and endosymbiotic microorganisms, particularly from the Rickettsia and Wolbachia groups. We observed a clear association between Rickettsia species and ticks, while Wolbachia was predominantly found in fleas. Additionally, other important microorganisms were identified, including Anaplasma phagocytophilum, Rickettsia conorii, and different strains of Wolbachia that serve as endosymbionts in various arthropods. These results underscore the importance of fleas and ticks in the transmission of both pathogenic and endosymbiotic microorganisms. The distinct patterns of association between specific pathogens and vectors provide insight into their transmission dynamics. Identifying pathogens such as Anaplasma phagocytophilum and Rickettsia conorii further highlights the need for continued research into vector-borne diseases in Colombia. Understanding the interactions between endosymbionts and pathogenic microorganisms in these vectors could lead to the development of more effective strategies for controlling diseases transmitted by fleas and ticks.

Zika virus: advancing a priority research agenda for preparedness and response

The 2015-16 Zika virus epidemic emerged in the Americas and rapidly spread throughout the region and beyond, showing the epidemic potential of this mosquito-borne Orthoflavivirus and its capacity to cause severe congenital malformations and neurological sequelae. WHO declared the Zika virus epidemic a public health emergency of international concern in 2016. Despite this declaration, there are no licensed Zika virus vaccines, therapeutics, or diagnostic tests appropriate for routine antenatal screening. To address this absence of essential tools to detect and mitigate the threat of future Zika virus outbreaks, a group of global experts developed a priority agenda for Zika virus research and development. This Series paper summarises crucial challenges and knowledge gaps and outlines a comprehensive strategy to advance research, surveillance, global capacity, policy, and investment for Zika virus preparedness and response.

Distribution of Anophelinae (Diptera: Culicidae) and challenges for malaria elimination in Brazil

In 1909, Arthur Neiva published an article titled "Contribuição para os estudos dos dipteros. Observação sobre a biolojia e sistematica das anofelinas brasileiras e suas relações com o impaludismo", highlighting the biology, ecology, and distribution of Anophelinae mosquitoes and the need for more taxonomic studies in Brazil. This came 11 years after Ronald Ross and Grassi demonstrated mosquito roles in transmitting Plasmodium to birds and humans. Despite considerable advances in the understanding of Anophelinae species, knowledge remains insufficient given the complexity of Brazil's ecosystems, the intensified anthropogenic environmental changes since the mid-20th century, and the persistent public health challenges posed by malaria. This perspective article presents the distribution of Plasmodium vectors and potential vector species in Brazil using climate variables and a maximum entropy model. Geographical distribution maps of Anophelinae species, including putative species, are provided. The article also discusses the current knowledge of vector species distribution in relation to Brazil's malaria elimination plan, along with the ecological and anthropogenic factors influencing vector distribution.

Identifying mosquito plant hosts from ingested nectar secondary metabolites

Establishing how plants contribute food and refuge to insects can be challenging for small species that are difficult to observe in their natural habitat, such as disease vectoring mosquitoes. Currently indirect methods of plant-host identification rely on DNA sequencing of ingested plant material but are often unsuccessful for small insects that feed primarily on plant sugars or have little contact with plant cells. Here we developed an innovative approach to determine species-specific phytophagy by detecting taxon-specific plant secondary metabolites (PSMs) in nectar. Two mosquito species were exposed to three PSMs, each present in the nectar of a known plant host, firstly from dosed sucrose solutions and secondly from flowers. Both experiments yielded high rates of PSM detection in mosquitoes using liquid chromatography-mass spectrometry (LC-MS). PSMs were consistently detected in mosquitoes up to 8 h post-ingestion. In experiments consisting of two or three plant species, multiple PSMs from different host plants could be detected. These positive results demonstrate that PSMs could be useful indicators of insect plant-hosts selection in the wild. With expanded knowledge of nectar-based PSMs across a landscape, improved knowledge of plant-host relationships could be achieved where direct observations in their natural habitat are lacking. Increasing understanding of vector insect ecology will have an important role in tackling vector-borne disease.

Modeling the non-integer dynamics of a vector-borne infection with nonlocal and nonsingular kernel

Vector-borne infections impose a significant burden on global health systems and economies due to their widespread impact and the substantial resources required for prevention, control, and treatment efforts. In this work, we formulate a mathematical model for the transmission dynamics of a vector-borne infection with the effect of vaccination through the Atangana-Baleanu derivative. The solutions of the model are positive and bounded for positive initial values of the state variable. We presented the basic concept and theory of fractional calculus for the analysis of the model. We determine the threshold parameter, denoted by [Formula: see text], using the next-generation matrix method. The local asymptotic stability of the system at the disease-free equilibrium is analyzed. To establish the existence of solutions for the proposed model, we employ fixed-point theory. A numerical scheme is developed to visualize the system's dynamical behavior under varying input parameters. Numerical simulations are conducted to illustrate how these parameters influence the dynamics of the system. The results highlight key factors affecting the transmission and control of vector-borne diseases, offering insights into strategies for prevention and mitigation.

Monitoring of Pathogens Carried by Imported Flies and Cockroaches at Shenzhen Ports

This study tested the efficacy of xenomonitoring using contaminated flies and cockroaches at ports in Shenzhen by analysing sample data from imported flies and cockroaches from October 2023 to April 2024 to identify the pathogens they carried. Among all the samples of flies and cockroaches collected, Musca domestica vicina and Blattella germanica accounted for the highest proportion, 27.59% and 66.47%, respectively. Their positive rates for carrying Staphylococcus aureus were also the most significant, reaching 4.35% and 6.47%, respectively. The imported flies and cockroaches mainly came from Asia, with the highest proportion coming from Hong Kong, at 97.71% and 92.11%, respectively. Metagenomic sequencing indicated that the pathogens carried by the flies and cockroaches from different regions of Asia were generally similar but showed some differences. Flies from Southeast Asia, East Asia, South Asia, and West Asia and cockroaches from Southeast Asia, East Asia, and West Asia harboured unique opportunistic pathogens capable of causing gastrointestinal and respiratory infections in humans. Specifically, flies carried pathogens such as Campylobacter jejuni, Bacillus anthracis, Bacteroides fragilis, and Bordetella bronchiseptica, while cockroaches carried B. fragilis, Clostridium tetani, and Bacillus cereus. Our findings provide data support for future risk assessments of pathogens carried by imported vectors.

Fighting Strategies Against Chagas' Disease: A Review

Chagas disease, caused by Trypanosoma cruzi, remains a significant public health challenge, particularly in Latin America, where it is one of the most neglected diseases and is primarily transmitted by triatomine insects. The disease exhibits complexity due to its diverse transmission routes, including vectorial and non-vectorial mechanisms such as blood transfusions and congenital transmission. Effective monitoring and control strategies are critical to mitigating its impact. This review focuses on current monitoring and control efforts, emphasizing the importance of enhanced surveillance systems, improved risk assessments, and integrated vector control programs. Surveillance plays a pivotal role in early detection and timely intervention, particularly in endemic regions, while vector control remains central to reducing transmission. Moreover, the development of novel diagnostic tools, treatments, and vaccines is a crucial step in advancing control efforts. This review also highlights the involvement of local governments, international organizations, and civil society in executing these strategies, stressing the need for sustained political commitment to ensure the success of public health programs. By addressing key challenges in monitoring, control, and prevention, this review aims to provide insights and recommendations to further global efforts in reducing the burden of Chagas disease.

Elevating larval source management as a key strategy for controlling malaria and other vector-borne diseases in Africa

Larval source management (LSM) has a long history of advocacy and successes but is rarely adopted where funds are limited. The World Health Organization (WHO) guidelines on malaria prevention recommend the use of LSM as a supplementary intervention to the core vector control methods (insecticide-treated nets and indoor residual spraying), arguing that its feasibility in many settings can be limited by larval habitats being numerous, transient, and difficult to find or treat. Another key argument is that there is insufficient high-quality evidence for its effectiveness to support wide-scale implementation. However, the stagnation of progress towards malaria elimination demands that we consider additional options to the current emphasis on insecticidal commodities targeting adult mosquitoes inside homes. This letter is the result of a global, crossdisciplinary collaboration comprising: (a) detailed online expert discussions, (b) a narrative review of countries that have eliminated local malaria transmission, and (c) a mathematical modeling exercise using two different approaches. Together, these efforts culminated in seven key recommendations for elevating larval source management as a strategy for controlling malaria and other mosquito-borne diseases in Africa (Box 1). LSM encompasses the use of larvicide (a commodity) as well as various environmental sanitation measures. Together, these efforts lead to the long-term reduction of mosquito populations, which benefits the entire community by controlling both disease vector and nuisance mosquitoes. In this paper, we argue that the heavy reliance on large-scale cluster-randomized controlled trials (CRTs) to generate evidence on epidemiological endpoints restricts the recommendation of approaches to only those interventions that can be measured by functional units and deliver relatively uniform impact and, therefore, are more likely to receive financial support for conducting these trials. The explicit impacts of LSM may be better captured by using alternative evaluation approaches, especially high-quality operational data and a recognition of locally distinct outcomes and tailored strategies. LSM contributions are also evidenced by the widespread use of LSM strategies in nearly all countries that have successfully achieved malaria elimination. Two modelling approaches demonstrate that a multifaceted strategy, which incorporates LSM as a central intervention alongside other vector control methods, can effectively mitigate key biological threats such as insecticide resistance and outdoor biting, leading to substantial reductions in malaria cases in representative African settings. This argument is extended to show that the available evidence is sufficient to establish the link between LSM approaches and reduced disease transmission of mosquito-borne illnesses. What is needed now is a significant boost in the financial resources and public health administration structures necessary to train, employ and deploy local-level workforces tasked with suppressing mosquito populations in scientifically driven and ecologically sensitive ways. In conclusion, having WHO guidelines that recognize LSM as a key intervention to be delivered in multiple contextualized forms would open the door to increased flexibility for funding and aid countries in implementing the strategies that they deem appropriate. Financially supporting the scale-up of LSM with high-quality operations monitoring for vector control in combination with other core tools can facilitate better health. The global health community should reconsider how evidence and funding are used to support LSM initiatives.

One-Step Multiplex Polymerase Chain Reaction Assay for the Detection of Major Disease-Transmitting Mosquito Vectors in India

Mosquitoes are important vectors that transmit viral, protozoan, and helminthic diseases across the world. Climate change and unplanned urbanization are accelerating the spread of these diseases. Controlling vector-borne diseases can be performed most effectively through vector control. Inadequate knowledge of vector bionomics is an impediment and can lead to inappropriate vector control efforts. However, the conventional methods of vector identification are based on morphological differences, demand a significant amount of time and specific skills, and are often misleading. An efficient and affordable solution is needed to quickly and accurately identify pooled samples from vast geographical territories. To ensure the correct identification of distorted or pooled samples in India, a set of definitive steps is required, including the construction of unique primers and the standardization of a one-step assay based on the second internal transcribed spacer gene of the ribosomal DNA. We have successfully developed and confirmed a highly efficient one-step multiplex reverse transcriptase polymerase chain reaction assay for the accurate identification of major mosquito vectors, especially in the cases of both the adult and larval forms of Anopheles sp., Aedes sp., and Culex sp. Hence, the specificity, universality, and uniqueness of these primers could serve as a critical tool for the rapid one-step and one-reaction identification of mosquitoes to control mosquito-borne disease outbreaks and public health emergencies.

Impact of Titanium Mining and Other Anthropogenic Activities on Malaria Positivity Rates and Parasitemia in Five Selected Study Sites in Msambweni Subcounty, Kwale County, Kenya

Africa was home to 95% of malaria cases and deaths in 2021. The negative impacts of malaria can be aggravated by social-economic-environmental factors, more so agroeconomic practices such as irrigation, mining, and dam construction. The aim of this study was to investigate the impact of water harvesting, sugarcane farming, and mining activities on Plasmodium falciparum positivity rates and parasitemia densities in five selected sites in Msambweni Subcounty, Kwale Kenya. A cross-sectional concurrent mixed methods study was used to collect data. Kwale County was selected due to the high malaria endemicity possibly attributable to the suitable vector habitat characterized by the major anthropogenic activities. The study had five different arms of investigation; the first arm was the control (C), second dam (D) site, third sugarcane (S) site, fourth mining (M) site, and fifth dam-sugarcane-mining (DMS) site. Each of the 1025 consenting participants from 208 households provided a single blood sample for determining malaria prevalence and parasitemia using rapid diagnostic kit and microscopy. Overall, the malaria positivity rate was 22.9% by rapid diagnostic testing (RDT) and 20.1% by microscopy. P. falciparum observation by RDT was highest in the DMS site with 33.7% followed by S site with 26.8%, D site with 23.3%, and M site with 17.6%, and the least was the C site with 11.0%. The overall parasitemia density (parasite counts per 200 white blood cells) was 8.4 with a site-specific density of 18.7, 8.6, 7.1, 3.7, and 3.1 for DMS, S, D, M, and C sites, respectively. Univariable analysis of factors associated with malaria infection showed that participants in the DMS site were four times more likely to be infected with malaria (odds ratio (OR) = 4.1, p < 0.001) compared to those in the C site. Malaria vector and human host interactions are often enhanced by suitable environmental conditions especially ambient temperature which accelerate parasite growth in the mosquito and humidity. Anthropogenic activities may open up new breeding sites for the vector or increase human-Anopheles infective contact hours, hence the different positivity rates and intensities in P. falciparum transmission. The study results showed that prevalence of malaria and parasitemia was highest in areas where all the three anthropogenic activities were taking place. In the single-activity site, sugarcane farming predisposed participants to high malaria burden. Characterized relational interplay between these anthropogenic activities and P. falciparum parasitemia will be useful in developing tailored strategies towards optimized malaria control interventions in areas with and without anthropogenic activities.

Vector borne disease control interventions in agricultural and irrigation areas in sub-Saharan Africa: A systematic review

Irrigation farming has raised concerns about the steady transmission and introduction of new vector-borne infectious diseases (VBD) in the areas involved. This systematic review aimed to determine interventions that are effective for the management and control of VBDs in irrigation areas in sub-Saharan Africa (SSA). We searched the literature on VBD interventions in SSA from published and grey literature without specifying the publication year. A search strategy identified 7768 records from various databases, and after screening, 16 were included in the final analysis. Results showed various VBD control interventions were effective, including indoor residue spray (IRS), insect-treated nets (ITN), larva source management (LSM), mass drug administration (MDA), integrated vector management (IVM), and mollusciciding. IVM was commonly practiced, and its success was because of the complementarity of the various interventions involved. Successful VBD control interventions led to improved health amongst irrigation communities and consequently improved agricultural productivity. However, some challenges to these interventions were identified, which include seasonal changes and climate variability, insecticide and drug resistance, and farmers' attitudes toward accepting the interventions. Regardless, results showed that VBD control and management can be integrated into irrigation farming before or after the establishment of the irrigation scheme.

Host preference of Anopheles stephensi mosquitoes for blood feeding in south of Iran: Insights from Multiplex-PCR analysis

BACKGROUND

The study aims to determine the host preference for blood feeding among potential hosts of Anopheles stephensi in Iran, using the Multiplex-PCR method. An. stephensi is the primary malaria vector in urban areas of South Asia and the Middle East, including southern Iran, where approximately 30.21% of malaria cases are urban. This trend has become more evident during the recent outbreaks in Iran, driven by infections of Plasmodium falciparum, Plasmodium vivax, and as well as mixed infections. Hormozgan province, one of the most endemic areas in Iran, was selected for its critical public health significance. This study builds on the validated efficiency of Multiplex-PCR for blood meal analysis by applying it to mosquitoes in southern Iran.

METHODS

In 2021, mosquitoes were collected monthly from three coastal villages in Bandar Abbas county, Hormozgan province, using WHO-recommended collection methods. Blood-fed An. stephensi mosquitoes were dissected, and their stomach contents analysed via Multiplex-PCR to identify human and animal blood sources.

RESULTS

Of 77 An. stephensi samples analysed, humans were the most common host was humans (29.9%), followed by mammals (19%), dogs (2.6%), and birds (1.3%). Mixed blood meals were detected in 34% of samples, including 23% with human and other hosts. Informal observations suggest that domestic animals such as goats, sheep, and chickens are commonly present near homes in these areas.

CONCLUSION

Approximately 50% of An. stephensi blood meals were sourced from humans, with 29% exclusively from humans and 23% from mixed hosts. Domestic animals such as goats, sheep, and chickens appear to attract mosquitoes, highlighting their potential role in malaria dynamics. Zooprophylaxis, alongside existing measures like insecticide residual spraying, insecticide-treated bed nets, and personal protection strategies, may strengthen urban malaria control. Further research on the ecological and behavioural drivers of mosquito host selection in urban settings is warranted.

Mosquito-disseminated pyriproxyfen for mosquito-borne disease control in Belo Horizonte, Brazil: a pragmatic, before-after control-intervention paired-series trial

BACKGROUND

Mosquitoes transmit important human pathogens, including dengue virus, but are notoriously hard to control. Mosquito-disseminated pyriproxyfen (MDPPF) uses the mosquitoes themselves to transfer particles of pyriproxyfen, a potent larvicide and pupicide, from lure dissemination stations to untreated larval habitats. MDPPF can reduce mosquito densities, but possible epidemiological effects remain to be measured. We aimed to investigate whether MDPPF can help curb mosquito-borne disease transmission.

METHODS

In this pragmatic, before-after control-intervention paired-series (BACIPS) trial conducted in Belo Horizonte, Brazil, municipal vector-control staff deployed, then serviced monthly (from November, 2017, to December, 2019), 2481 pyriproxyfen dissemination stations in a nine-neighbourhood cluster with a history of high dengue endemicity; nine adjacent neighbourhoods were designated as a buffer area, and the remaining 258 city neighbourhoods as the control area. The primary epidemiological outcome of the trial was dengue incidence. Based on official dengue-notification records broken down by week and neighbourhood (ie, week-neighbourhood case counts; N=265 162 cases in total) from Jan 1, 2016, to Dec 31, 2019, we estimated intervention effects on incidence using a BACIPS approach and negative-binomial generalised linear mixed models (GLMMs). Zika and chikungunya cases were too rare to be assessed with confidence.

FINDINGS

Week-neighbourhood dengue incidence ranged from 0 to 379·5 cases per 10 000 residents, with epidemic outbreaks recorded in 2016 and 2019. Intention-to-treat, BACIPS-GLMM adjusted estimates indicate that MDPPF deployment was associated with a net 29% (95% CI 21-36; p=4·7 × 10-10) average decrease of dengue incidence in intervention neighbourhoods and a net 21% (12-30; p=2·7 × 10-5) average decrease in buffer neighbourhoods. In contrast, and due in part to larger uncertainties, average incidence rates were statistically indistinguishable across areas before the intervention (intervention area p=0·47; buffer area p=0·11) and across trial periods in control neighbourhoods (p=0·74). Hence, in the all-too-common scenario of a 100 000-case outbreak, public health managers could expect MDPPF to reduce the strain on the health-care system by at least about 29 000 (21 000-36 000) symptomatic cases.

INTERPRETATION

Our results suggest that MDPPF can help prevent dengue under the many operational constraints of real-world vector-control interventions and despite incomplete coverage and potential dilution of intervention effects. MDPPF holds promise as an additional tool for dengue control.

FUNDING

Coordenação-Geral de Vigilância de Arboviroses, Secretaria de Vigilância em Saúde e Ambiente, Ministry of Health, Brazil, Secretaria Municipal de Saúde de Belo Horizonte, Brazil, and Fundação de Amparo à Pesquisa do Estado do Amazonas, Brazil.

Intraspecific genetic variation in the lymphatic filariasis vector Mansonia dives (Diptera: Culicidae) in Thailand: Hidden species or genetically divergent populations?

Mansonia dives is recognized as a vector for brugian filariasis in Thailand. A recent study analyzing the cytochrome c oxidase subunit I (COI) gene revealed two distinct clades within the Ma. dives population in Thailand. This study aimed to examine the genetic diversity and structure of Ma. dives using the COI gene and the internal transcribed spacer 2 (ITS2) region to determine the presence of distinct species or genetically divergent populations. We analyzed 60 COI and 60 ITS2 sequences from Ma. dives populations in Narathiwat, Ranong, Tak, and Trat. The results showed a nucleotide diversity of 0.019 and a haplotype diversity of 0.979 for the COI gene, while the ITS2 region displayed a nucleotide diversity of 0.005 and a haplotype diversity of 0.545. Phylogenetic and haplotype network analyses of the COI gene identified two genetic lineages: one confined to Trat and another encompassing the other sites. However, species delimitation methods suggested that these genetic differences were insufficient to classify the lineages as distinct species. In contrast, the ITS2 analysis indicated a uniform genetic pattern across all populations. We conducted neutrality tests and mismatch distribution to examine the demographic history. For the COI gene, Tajima's D was slightly positive and non-significant (0.014), while Fu's Fs was negative (-9.750), indicating a potential expansion phase. Conversely, for the ITS2 region, Tajima's D and Fu's Fs were positive and non-significant, suggesting that the population might be in equilibrium or undergoing contraction. Moreover, the mismatch distribution analysis for the ITS2 region was inconclusive. The apparent discrepancies between these markers indicate the presence of genetically divergent populations, rather than distinct species.

Lumpy skin disease: A growing threat to the global livestock industry

Lumpy Skin Disease (LSD) is an infectious disease in cattle caused by the Lumpy Skin Disease Virus by the Poxviridae family. Historically, LSD was first documented in Northern Rhodesia (now Zambia) in 1929 as a symptom of bug bite poisoning or hypersensitivity, described as pseudo-urticaria. This disease, which causes widespread malaise and persistent weakness, is a serious, economically devastating, and reportable condition that lowers cattle output. The illness starts as a biphasic fever. After fever, emaciation, ocular discharge, and agalactia, the clinical signs of a minor infection develop as one or two nodular lumps appear 2-3 days later. In particular, the skin of the muzzle, back, nostrils, legs, scrotum, eyelids, lower ears, nasal, perineum, oral mucosa, and tail display painful, hyperemic, nodular lesions. A number of diagnostic methods, such as virus isolation in cell culture, transmission electron microscopy, immunohistochemistry, direct and indirect fluorescent antibody testing, agar gel immunodiffusion, enzyme-linked immunosorbent assay, western blotting, and serum neutralization test (SNT), are used to confirm the clinical diagnosis. This disease is spread by arthropods such as flies, mosquitoes, and ticks. It is most common during the rainy season, when there is a high number of biting insects, and it declines during the dry season. LSD has direct and indirect economic impacts on livestock and the industry. Since there is no effective antiviral medication to treat LSD, the only viable method of disease containment is vaccination.

Deep learning in disease vector image identification

Vector-borne diseases (VBDs) represent a critical global public health concern, with approximately 80% of the world's population at risk of one or more VBD. Manual disease vector identification is time-consuming and expert-dependent, hindering disease control efforts. Deep learning (DL), widely used in image, text, and audio tasks, offers automation potential for disease vector identification. This paper explores the substantial potential of combining DL with disease vector identification. Our aim is to comprehensively summarize the current status of DL in disease vector identification, covering data collection, data preprocessing, model construction, evaluation methods, and applications in identification spanning from species classification to object detection and breeding site identification. We also discuss the challenges and possible prospects for DL in disease vector identification for further research. © 2024 Society of Chemical Industry.

A phytoplasma effector suppresses insect melanization immune response to promote pathogen persistent transmission

Insect melanization triggered by the conversion of prophenoloxidase to active phenoloxidase via serine proteases (SPs) is an important immediate immune response. However, how phytoplasmas evade this immune response to promote their propagation in insect vectors remains unknown. Here, we demonstrate that infection of leafhopper vectors with rice orange leaf phytoplasma (ROLP) activates the mild melanization response in hemolymph. ROLP-encoded effector protein SRP1 is highly expressed in leafhopper hemolymph, where it competitively binds to SP2, thereby inhibiting SP2-mediated cleavage of prophenoloxidase into active phenoloxidase. Consequently, microinjection of SRP1 effectively suppresses the melanization response and enhances ROLP propagation. The histidine residue at position 23 of SRP1 is essential for SRP1-SP2 interaction, and the mutation of this position abolishes its ability to inhibit such SP2-meidated cleavage, ultimately promoting melanization response and inhibiting ROLP propagation. Our findings provide insights into how phytoplasmas antagonize insect melanization response to facilitate their persistent transmission.

Identification of climate-sensitive disease incidences in vietnam: A longitudinal retrospective analysis of infectious disease rates between 2014 and 2022

Objective

There is a growing correlation between the rise in infectious diseases and climate change; however, little is known about the interactions and mixed effects of climate factors on infectious diseases.

Method

We conducted a retrospective longitudinal study spanning 108 consecutive months from 2014 to 2022 in Can Tho, Vietnam to identify common infectious diseases (excluding tuberculosis, HIV, and COVID-19) and their associations with climate change and determine which common diseases presented concurrently with the COVID-19 period using multivariate linear regression, receiver operating characteristic (ROC) curve analysis, Bayesian kernel machine regression (BKMR) and orthogonal partial least squares discriminant analysis.

Result

The five infectious diseases with the highest average incidence rates per 100,000 people were diarrhea; hand, foot, and mouth disease (HFMD); dengue fever; viral hepatitis; and influenza. Positive associations with humidity were observed for dengue fever and HFMD. Temperature was positively associated with malaria. Negative associations were found between humidity and both chickenpox and tetanus. Diarrhea (AUC = 0.79; 95 % CL = 0.70-0.87) and dengue fever (AUC = 0.74; 95 % CL = 0.62-0.83) emerged as the most influential diseases both before and during the COVID-19 period. In our BKMR analysis, we found a significant association between the combined influence of temperature and humidity and the occurrence of dengue fever and HFMD, especially when all climate factors were at or above their 60th percentile relative to their values at the 50th percentile. Temperature emerged as the primary driver associated with the occurrence of infectious diseases.

Conclusion

These findings underscore the importance of implementing robust surveillance, prevention, and control measures by public health authorities in Can Tho. Initiatives like vaccination campaigns, vector control programs, public education on hygiene practices, and strengthening healthcare infrastructure are crucial for mitigating the spread of infectious diseases and safeguarding public health in the region.

Zinc from an Essential Element to an Antiparasitic Therapeutic Agent

Tropical parasitic diseases affect millions of people around the world, particularly in poor countries. The human parasitic diseases that will be covered in this review are malaria and neglected diseases, such as leishmaniasis, Chagas disease, and African trypanosomiasis. The current treatments for these diseases present several problems, such as the development of drug resistance, very limited drugs available in the clinic, significant side effects of the drugs, and a long treatment period. For these reasons, there is an urgent need to develop new chemotherapeutics to eradicate or eliminate these diseases. Zinc-based drugs against parasitic diseases could be an alternative therapy to overcome the difficulties of the approved metallodrugs as antiparasitic agents. Zinc-based drugs are becoming an exciting field of research because zinc is an essential element that can lead to the development of multitarget antiparasitic agents, which are reviewed here.

Seroprevalence of dengue, Zika, and chikungunya in São Sebastião, Brazil (2020-2021): a population-based survey

BACKGROUND

Urban arboviruses pose a significant global burden, particularly in tropical regions like Brazil. São Sebastião, a lower-middle-class urban area just 26 km from the Brazilian capital, is an endemic area for dengue. However, asymptomatic cases may obscure the actual extent of the disease. In this study, we measured the seroprevalence of dengue, Zika virus, and chikungunya, and compared these findings with surveillance data.

METHODS

A cross-sectional study was conducted involving 1,535 households. ELISA serological tests were performed to detect IgM and IgG antibodies against dengue, Zika virus, and chikungunya. History of previous exposure to arboviruses, data on age, gender, and education level were collected through a questionnaire. Participants who tested positive for IgM and/or IgG were classified as soropositive. Statistical analyses included tests for normality, associations, mean comparisons, and correlations. Positive serological results were compared with cases captured by local epidemiological surveillance.

RESULTS

The study included 1,405 individuals, divided into two groups related to pre-pandemic and pandemic COVID-19 phases. Among participants, 0.7% to 28.8% self-reported history of dengue, Zika, or chikungunya. However, the estimated overall seroprevalence was 64.3% (95% CI: 61.8-66.7) for dengue virus, 51.4% (95% CI: 48.8-53.9) for Zika virus, and 5.4% (95% CI: 4.4-6.7) for chikungunya virus. Multiple arboviruses were noted at 4.0% (95% CI: 3.1-5.1). Advancing age and lower education were associated with higher exposure to arboviruses (p < 0.05). The estimated number of urban arboviral infections was 84 times higher than reported cases.

CONCLUSIONS

The large gap between seroprevalence estimates and cases captured by epidemiological surveillance suggests a silent circulation of arboviruses, highlighting the need for comprehensive serological surveys in endemic regions. Addressing these discrepancies is crucial for effective resource allocation and implementation of public health interventions.

A Comprehensive Review: Biology of Anopheles squamosus, an Understudied Malaria Vector in Africa

With ongoing global efforts to eliminate malaria, several countries have entered a pre-elimination stage, in which populations of the primary mosquito vector are reduced and the rates of malaria transmission are low. Efforts to eliminate malaria have changed the dynamics of disease transmission, causing a shift in anopheline community composition in some regions. One of the most abundant species of Anopheles found in pre-elimination areas, such as southern Africa, is Anopheles squamosus (Theobald, 1901; Diptera: Culicidae). Although An. squamosus has been documented across the African continent, limited information is available about its biology. Knowing what, when, and where the malaria vector bites humans can help develop effective malaria control strategies. The aim of this review is to compile the information available on An. squamosus's biology, ecology, distribution, behavior, and potential role in disease transmission. The review of current literature suggested that An. squamosus is abundant throughout the African continent. Studies indicate that this species occupies the same range and exhibits similar behaviors to primary malaria vectors in southern and eastern African countries, like Zambia. In conclusion, An. squamosus continues to be an understudied species that has circumvented disease control measures and further studies are needed to develop effective control strategies.

Transcriptome Analysis of Culex pipiens quinquefasciatus Larvae Exposed to a Semi-Lethal Dose of Vermistatin

Culex pipiens quinquefasciatus is a notorious vector transmitting severe diseases such as Zika virus and West Nile virus to humans worldwide. Vermistatin is a type of funicon-like compound and was first isolated from Penicillin vermiculatum in the 1970s. Vermistatin has shown promising activity against Cx. p. quinquefasciatus larvae in our previous research. Here, we conducted a transcriptomic analysis of Cx. p. quinquefasciatus larvae treated with a median lethal concentration of 28.13 mg/L vermistatin. Differential expression analysis identified 1055 vermistatin-responsive genes, with 477 downregulated and 578 upregulated. Gene Ontology annotation and enrichment analysis revealed the metabolic process to be the most significantly affected biological process, the membrane to be the most significantly affected cellular component, and catalytic activity to be the most significantly affected molecular function. Kyoto Encyclopedia of Genes and Genomes pathway analysis classified the differential expression genes into six major categories, with metabolism and organismal systems being the most enriched. Fifty-five pathways were significantly enriched, with the hematopoietic cell lineage, renin-angiotensin system, cholesterol metabolism, and peroxisome proliferator-activated receptor signaling pathways among the top altered pathways. Furthermore, 32 potential detoxification-related genes were differentially expressed, with 3 cytochrome P450s, 2 ABC transporters, and 1 UGT induced by vermistatin. This study provides insights into the molecular mechanisms of vermistatin's action against Cx. p. quinquefasciatus larvae, highlighting potential targets for novel mosquito control strategies.

Overexpression of multiple cytochrome P450 genes with and without knockdown resistance mutations confers high resistance to deltamethrin in Culex quinquefasciatus

BACKGROUND

The cytochrome P450s-mediated metabolic resistance and the target site insensitivity caused by the knockdown resistance (kdr) mutation in the voltage-gated sodium channel (vgsc) gene were the main mechanisms conferring resistance to deltamethrin in Culex quinquefasciatus from Thailand. This study aimed to investigate the expression levels of cytochrome P450 genes and detect mutations of the vgsc gene in deltamethrin-resistant Cx. quinquefasciatus populations in Thailand.

METHODS

Two field-collected strains of Cx. quinquefasciatus, Cq_SP and Cq_NiH, were selected with deltamethrin to generate the resistant strains Cq_SP-R and Cq_NiH-R, respectively. Bioassays were tested on larvae and adults of each strain according to WHO methods. Eight cytochrome P450 genes were analyzed for the expression level using quantitative real time-PCR. The cDNA of mosquitoes was amplified and sequenced for four fragments of vgsc gene. The kdr L1014F mutation and the haplotype of the CYP9M10 gene were detected in survivor and dead mosquitoes after exposure to the deltamethrin WHO test paper. Statistical analyses were performed using Fisher's exaction test.

RESULTS

Bioassay tests revealed a significantly higher resistance level in Cq_SP-R than in Cq_NiH-R strains in both larvae and adults. All eight cytochrome P450 genes were significantly overexpressed in larvae of Cq_NiH-R strain compared to the parent and susceptible Cq_Sus strains. The CYP6AA7 and CYP9J34 genes had the highest expression ratios, exceeding 24-fold in Cq_NiH-R larvae. In Cq_SP-R strain, the CYP4H34 and CYP9J34 genes were overexpressed in both stages. The kdr L1014F mutation was found in Cq_SP-R and its parent Cq_SP strains with a significantly higher mutant allele frequency in the survivor mosquitoes than in dead mosquitoes (P < 0.0001). The V240M and novel L925F mutations were found only in Cq_SP-R strain. Heterozygous genotype for the D-Cu( +)/Cu(-) of CYP9M10 gene was detected in Cq_NiH and Cq_NiH-R strains but other strains were mostly homozygous for the Cu(-)/Cu(-).

CONCLUSIONS

Overexpression of multiple cytochrome P450 genes alone has a relatively minor impact on resistance. The combined mechanisms of cytochrome P450- and kdr-mediated resistance result in significantly higher resistance to deltamethrin in Cx. quinquefasciatus. This study supports sustainable public health initiatives in Thailand to address the evolving challenges of insecticide resistance.

Repellency of Essential Oils and Plant-Derived Compounds Against Aedes aegypti Mosquitoes

Plant-based oils have a long history of use as insect repellents. In an earlier study, we showed that in a 10% concentration, geraniol, 2-phenylethl propionate, and the plant-based essential oils clove and cinnamon effectively protected from mosquito bites for over 60 min. To expand on this study, we reanalyzed our GC-MS data to identify the short organic constituents of these oils. We then used an arm-in-cage assay to test the repellency of different concentrations and combinations of these oils and pure compounds. We found a sigmoidal relationship between the complete protection time from mosquito bites and the concentration of these oils. The complete protection times we recorded for combinations of these oils suggest an absence of additive effects. The results of this study can inform the development of novel, effective, and plant-based insect repellents.

Repellency and toxicity of long-lasting insecticide-treated bed nets (LLINs) to bed bugs

Vector control is essential for eliminating malaria, a vector-borne parasitic disease responsible for over half a million deaths annually. Success of vector control programs hinges on community acceptance of products like long-lasting insecticide-treated nets (LLINs). Communities in malaria-endemic regions often link LLIN efficacy to their ability to control indoor pests such as bed bugs (Cimex lectularius L. and Cimex hemipterus (F.)) (Hemiptera: Cimicidae). Despite this, little is known about the potential repellent effects and toxicity of LLINs to bed bugs. Herein, we demonstrate for the first time that commonly deployed LLINs lack olfactory and contact-based repellency to host-seeking C. lectularius from both insecticide-susceptible and insecticide-resistant populations. One LLIN (PermaNet Dual) was significantly attractive to both populations when exposed olfactorily, but not in contact assays, highlighting the complexity of bed bug-LLIN interactions. The insecticide resistant bed bugs experienced low mortality in 4 d of continuous exposure to LLINs. These results suggest that LLINs would likely not repel or eliminate bed bug infestations in malaria-endemic communities, further selecting for insecticide resistance and potentially disrupting vector control programs.

A Y chromosome-linked genome editor for efficient population suppression in the malaria vector Anopheles gambiae

Genetic control - the deliberate introduction of genetic traits to control a pest or vector population - offers a powerful tool to augment conventional mosquito control tools that have been successful in reducing malaria burden but that are compromised by a range of operational challenges. Self-sustaining genetic control strategies have shown great potential in laboratory settings, but hesitancy due to their invasive and persistent nature may delay their implementation. Here, instead, we describe a self-limiting strategy, designed to have geographically and temporally restricted effect, based on a Y chromosome-linked genome editor (YLE). The YLE comprises a CRISPR-Cas9 construct that is always inherited by males yet generates an autosomal dominant mutation that is transmitted to over 90% of the offspring and results in female-specific sterility. To our knowledge, our system represents a pioneering approach in the engineering of the Y chromosome to generate a genetic control strain for mosquitoes. Mathematical modelling shows that this YLE technology is up to seven times more efficient for population suppression than optimal versions of other self-limiting strategies, such as the widely used Sterile Insect Technique or the Release of Insects carrying a Dominant Lethal gene.