bims-mosdis 2023-04-30 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2023‒04‒30
nineteen papers selected by
Richard Halfpenny, Staffordshire University

Behavior of Adult Aedes aegypti and Aedes albopictus in Kinshasa, DRC, and the Implications for Control.
The influence of weather on the population dynamics of common mosquito vector species in the Canadian Prairies.
Screening of natural Wolbachia infection in mosquitoes (Diptera: Culicidae) from the Cape Verde islands.
First evidence for development of Plasmodium relictum (Grassi and Feletti, 1891) sporozoites in the salivary glands of Culex modestus Ficalbi, 1889.
Where boundaries become bridges: Mosquito community composition, key vectors, and environmental associations at forest edges in the central Brazilian Amazon.
Current observations on shifts in malaria vector biting behavior and changing vulnerability to malaria transmission in contrasting ecosystems in Western Kenya.
Differences in Longevity and Temperature-Driven Extrinsic Incubation Period Correlate with Varying Dengue Risk in the Arizona-Sonora Desert Region.
A Multi-Species Simulation of Mosquito Disease Vector Development in Temperate Australian Tidal Wetlands Using Publicly Available Data.
Increased malaria incidence following irrigation practices in the Endorheic Rift Valley Basin of Sidama Region, Ethiopia.
Potential risk sites and their relationship with dengue cases, Campinas municipality, Southeast Brazil.
Fusing an agent-based model of mosquito population dynamics with a statistical reconstruction of spatio-temporal abundance patterns.
Northern and Central Chile still free of emerging flaviviruses in mosquitoes (Diptera: Culicidae).
Unprecedented Outbreak of West Nile Virus - Maricopa County, Arizona, 2021.
Vector Competence of Aedes albopictus for Yellow Fever Virus: Risk of Reemergence of Urban Yellow Fever in Brazil.
Report of natural Mayaro virus infection in Mansonia humeralis (Dyar & Knab, Diptera: Culicidae).
Vector Competence of Culex quinquefasciatus from Brazil for West Nile Virus.
First Isolation and Genome Sequence Analysis of West Nile Virus in Mosquitoes in Brazil.
Assessing the Influence of Climate on the Spatial Pattern of West Nile Virus Incidence in the United States.
Spatial Distribution and Long-Term Persistence of Wolbachia-Infected Aedes aegypti in the Mentari Court, Malaysia.

Trop Med Infect Dis. 2023 Mar 30. pii: 207. [Epub ahead of print]8(4):

Behavior of Adult Aedes aegypti and Aedes albopictus in Kinshasa, DRC, and the Implications for Control.

Emile Zola Manzambi, Guillaume Binene Mbuka, Gillon Ilombe, Richard Mundeke Takasongo, Francis Wat'senga Tezzo, Maria Del Carmen Marquetti, Emery Metelo, Veerle Vanlerberghe, Wim Van Bortel.

  Yellow fever and chikungunya outbreaks-and a few dengue cases-have been reported in the Democratic Republic of the Congo (DRC) in recent years. However, little is known about the ecology and behavior of the adult disease vector species, Aedes aegypti and Aedes albopictus, in DRC. Preliminary studies showed important differences in Aedes behavior in DRC and Latin-American sites. Therefore, this study aimed to assess the host-seeking and resting behaviors of female Ae. aegypti and Ae. albopictus, and their densities in four communes of Kinshasa (Kalamu, Lingwala, Mont Ngafula and Ndjili). Two cross-sectional surveys were carried out, one in the dry season (July 2019) and one in the rainy season (February 2020). We used three different adult vector collection methods: BG-Sentinel 2, BG-GAT, and prokopack. Both Aedes species were clearly exophagic, exophilic, and sought breeding sites outdoors. The adult house index for Ae. aegypti exceeded 55% in all communes except Lingwala, where it was only 27%. The Adult Breteau Index (ABI) for Ae. aegypti was 190.77 mosquitoes per 100 houses inspected in the rainy season and 6.03 in the dry season. For Ae. albopictus, the ABI was 11.79 and 3.52 in the rainy and dry seasons, respectively. Aedes aegypti showed unimodal host-seeking activity between 6 h and 21 h. The exophagic and exophilic behaviors of both species point to the need to target adult mosquitoes outdoors when implementing vector control.

Keywords:  Aedes; Democratic Republic of the Congo; Kinshasa; exophagic; vector control

DOI:  https://doi.org/10.3390/tropicalmed8040207
Parasit Vectors. 2023 Apr 28. 16(1): 153

The influence of weather on the population dynamics of common mosquito vector species in the Canadian Prairies.

Cole Baril, Ben G Pilling, Milah J Mikkelsen, Jessica M Sparrow, Carlyn A M Duncan, Cody W Koloski, Stefanie E LaZerte, Bryan J Cassone.

  BACKGROUND: Mosquito seasonal activity is largely driven by weather conditions, most notably temperature, precipitation, and relative humidity. The extent by which these weather variables influence activity is intertwined with the animal's biology and may differ by species. For mosquito vectors, changes in weather can also alter host-pathogen interactions thereby increasing or decreasing the burden of disease.METHODS: In this study, we performed weekly mosquito surveillance throughout the active season over a 2-year period in Manitoba, Canada. We then used Generalized Linear Mixed Models (GLMMs) to explore the relationships between weather variables over the preceding 2 weeks and mosquito trap counts for four of the most prevalent vector species in this region: Oc. dorsalis, Ae. vexans, Cx. tarsalis, and Cq. perturbans.
RESULTS: More than 265,000 mosquitoes were collected from 17 sampling sites throughout Manitoba in 2020 and 2021, with Ae. vexans the most commonly collected species followed by Cx. tarsalis. Aedes vexans favored high humidity, intermediate degree days, and low precipitation. Coquillettidia perturbans and Oc. dorsalis activity increased with high humidity and high rainfall, respectively. Culex tarsalis favored high degree days, with the relationship between number of mosquitoes captured and precipitation showing contrasting patterns between years. Minimum trapping temperature only impacted Ae. vexans and Cq. perturbans trap counts.
CONCLUSIONS: The activity of all four mosquito vectors was affected by weather conditions recorded in the 2 weeks prior to trapping, with each species favoring different conditions. Although some research has been done to explore the relationships between temperature/precipitation and Cx. tarsalis in the Canadian Prairies, to our knowledge this is the first study to investigate other commonly found vector species in this region. Overall, this study highlights how varying weather conditions can impact mosquito activity and in turn species-specific vector potential.

Keywords:  Aedes; Culex; GLMM; Humidity; Rainfall; Temperature

DOI:  https://doi.org/10.1186/s13071-023-05760-x
Parasit Vectors. 2023 Apr 25. 16(1): 142

Screening of natural Wolbachia infection in mosquitoes (Diptera: Culicidae) from the Cape Verde islands.

Aires Januário Fernandes da Moura, Vera Valadas, Silvania Da Veiga Leal, Eddyson Montalvo Sabino, Carla A Sousa, João Pinto.

  BACKGROUND: Wolbachia pipientis is an endosymbiont bacterium that induces cytoplasmic incompatibility and inhibits arboviral replication in mosquitoes. This study aimed to assess Wolbachia prevalence and genetic diversity in different mosquito species from Cape Verde.METHODS: Mosquitoes were collected on six islands of Cape Verde and identified to species using morphological keys and PCR-based assays. Wolbachia was detected by amplifying a fragment of the surface protein gene (wsp). Multilocus sequence typing (MLST) was performed with five housekeeping genes (coxA, gatB, ftsZ, hcpA, and fbpA) and the wsp hypervariable region (HVR) for strain identification. Identification of wPip groups (wPip-I to wPip-V) was performed using PCR-restriction fragment length polymorphism (RFLP) assay on the ankyrin domain gene pk1.
RESULTS: Nine mosquito species were collected, including the major vectors Aedes aegypti, Anopheles arabiensis, Culex pipiens sensu stricto, and Culex quinquefasciatus. Wolbachia was only detected in Cx. pipiens s.s. (100% prevalence), Cx. quinquefasciatus (98.3%), Cx. pipiens/quinquefasciatus hybrids (100%), and Culex tigripes (100%). Based on the results of MLST and wsp hypervariable region typing, Wolbachia from the Cx. pipiens complex was assigned to sequence type 9, wPip clade, and supergroup B. PCR/RFLP analysis revealed three wPip groups in Cape Verde, namely wPip-II, wPip-III, and wPip-IV. wPip-IV was the most prevalent, while wPip-II and wPip-III were found only on Maio and Fogo islands. Wolbachia detected in Cx. tigripes belongs to supergroup B, with no attributed MLST profile, indicating a new strain of Wolbachia in this mosquito species.
CONCLUSIONS: A high prevalence and diversity of Wolbachia was found in species from the Cx. pipiens complex. This diversity may be related to the mosquito's colonization history on the Cape Verde islands. To the best of our knowledge, this is the first study to detect Wolbachia in Cx. tigripes, which may provide an additional opportunity for biocontrol initiatives.

Keywords:  Cape Verde; Culex pipiens; Culex tigripes; Genotyping; Mosquitoes; Wolbachia

DOI:  https://doi.org/10.1186/s13071-023-05745-w
Parasitol Res. 2023 Apr 26.

First evidence for development of Plasmodium relictum (Grassi and Feletti, 1891) sporozoites in the salivary glands of Culex modestus Ficalbi, 1889.

Dimitar Dimitrov, Aneliya Bobeva, Martin P Marinov, Mihaela Ilieva, Pavel Zehtindjiev.

  The competence of insect vectors to transmit diseases plays a key role in host-parasite interactions and in the dynamics of avian malaria and other haemosporidian infections (Apicomplexa, Haemosporida). However, the presence of parasite DNA in the body of blood-sucking insects does not always constitute evidence for their competence as vectors. In this study, we investigate the susceptibility of wild-caught mosquitoes (Culex spp.) to complete sporogony of Plasmodium relictum (cyt b lineage SGS1) isolated from great tits (Parus major L., 1758). Adult female mosquitoes were collected with a CO2 bait trap overnight. A set of 50 mosquitoes was allowed to feed for 3 h at night on a single great tit infected with P. relictum. This trial was repeated on 6 different birds. The bloodfed mosquitoes that survived (n = 68) were dissected within 1-2 days (for ookinetes, n = 10) and 10-33 days post infection (for oocysts and sporozoites, n = 58) in order to confirm the respective parasite stages in their organs. The experiment confirmed the successful development of P. relictum (cyt b lineage SGS1) to the stage of sporozoites in Culex pipiens L., 1758 (n = 27) and in Culex modestus (n = 2). Our study provides the first evidence that C. modestus is a competent vector of P. relictum isolated from great tits, suggesting that this mosquito species could also play a role in the natural transmission of avian malaria.

Keywords:  Avian malaria; Blood parasites; Competent vector; Parus major; SGS1; Transmission

DOI:  https://doi.org/10.1007/s00436-023-07853-z
PLoS Negl Trop Dis. 2023 Apr 26. 17(4): e0011296

Where boundaries become bridges: Mosquito community composition, key vectors, and environmental associations at forest edges in the central Brazilian Amazon.

Adam Hendy, Eduardo Hernandez-Acosta, Danielle Valério, Nelson Ferreira Fé, Claudia Reis Mendonça, Edson Rodrigues Costa, Eloane Silva de Andrade, José Tenaçol Andes Júnior, Flamarion Prado Assunção, Vera Margarete Scarpassa, Marcus Vinícius Guimarães de Lacerda, Michaela Buenemann, Nikos Vasilakis, Kathryn A Hanley.

Risk of spillover and spillback of mosquito-borne viruses in the neotropics, including yellow fever, dengue, Zika (Flaviviridae: Flavivirus), chikungunya, and Mayaro (Togaviridae: Alphavirus) viruses, is highest at ecotones where humans, monkeys, and mosquitoes coexist. With a view to identifying potential bridge vectors, we investigated changes in mosquito community composition and environmental variables at ground level at distances of 0, 500, 1000, and 2000 m from the edge of a rainforest reserve bordering the city of Manaus in the central Brazilian Amazon. During two rainy seasons in 2019 and 2020, we sampled 9,467 mosquitoes at 244 unique sites using BG-Sentinel traps, hand-nets, and Prokopack aspirators. Species richness and diversity were generally higher at 0 m and 500 m than at 1000 m and 2000 m, while mosquito community composition changed considerably between the forest edge and 500 m before stabilizing by 1000 m. Shifts in environmental variables mainly occurred between the edge and 500 m, and the occurrence of key taxa (Aedes albopictus, Ae. scapularis, Limatus durhamii, Psorophora amazonica, Haemagogus, and Sabethes) was associated with one or more of these variables. Sites where Ae. aegypti and Ae. albopictus were detected had significantly higher surrounding mean NDBI (Normalized Difference Built-up Index) values than sites where they were not detected, while the opposite was true for Sabethes mosquitoes. Our findings suggest that major changes in mosquito communities and environmental variables occur within 500 m of the forest edge, where there is high risk for contact with both urban and sylvatic vectors. By 1000 m, conditions stabilize, species diversity decreases, and forest mosquitoes predominate. Environmental variables associated with the occurrence of key taxa may be leveraged to characterize suitable habitat and refine risk models for pathogen spillover and spillback.

DOI: https://doi.org/10.1371/journal.pntd.0011296
Res Sq. 2023 Apr 10. pii: rs.3.rs-2772202. [Epub ahead of print]

Current observations on shifts in malaria vector biting behavior and changing vulnerability to malaria transmission in contrasting ecosystems in Western Kenya.

Irene Nzioki, Maxwell G Machani, Shirley A Onyango, Kevin K Kabui, Andrew K Githeko, Eric Ochomo, Guiyun Yan, Yaw A Afrane.

Background: Designing, implementing, and upscaling effective malaria vector control strategies necessitates understanding of when and where transmission occurs. This study assessed the biting patterns of potentially infectious malaria vectors at various hours, locations, and human behavior in different ecological settings in western Kenya. Methods: Hourly indoor and outdoor catches of human-biting mosquitoes were sampled from 1900 to 0700 hours for four consecutive nights in four houses per village using human landing collection method. The nocturnal biting activities of each Anopheles species were expressed as the mean number of mosquitoes landing per person per hour. The human behavior study was conducted via observations and questionnaire surveys. Species within Anopheles gambiae and Anopheles funestus complexes were differentiated by polymerase chain reaction (PCR) and the presence of Plasmodium falciparum circumsporozoite proteins (CSP) determined by enzyme-linked immunosorbent assay (ELISA). Results: Altogether, a total of 2,037 adult female Anophelines were collected comprising of A n. funestus s.l. (76.7%), An.gambiae s.l. (22.8%) and Anopheles coustani (0.5%). Overall, Anopheles funestus was the predominant species collected in Ahero (96.7%) while An. gambiae s.l was dominant in Kisian (86.6%) and Kimaeti (100%) collections. PCR results revealed that An. arabiensis constituted 80.5% and 79% of the An.gambiae s.l samples analysed from Ahero and Kisian respectively. An. gambiae s.s (hereafter An.gambiae )(98.1%) was the dominant species collected in Kimaeti. All the An. funestus s.l samples analysed belonged to An. funestus s.s ( hereafter An. funestus ). Indoor biting densities of Anopheles gambiae and An. funestus exceeded the outdoor biting densities in all sites. The peak biting occurred early morning between 0430-0630 hours in the lowlands for An. funestus both indoors and outdoors. In the highlands (Kimaeti), the peak biting of An.gambiae occurred between 0100-0200 hours indoors. Over 50% of the study population stayed outdoors from 1800 to 2200 hours and woke up at 0500 hours coinciding with the times highest numbers of vectors were collected. The sporozoite rate was higher in vectors collected outdoors, with An. funestus being the main malaria vector in the lowlands and An. gambiae in the highland. Conclusion: The study shows heterogeneity of Anophelines distribution, high outdoor malaria transmission, and peak biting activity by An. funestus (early morning ) when humans are not protected by bed nets in the lowland sites. Additional vector control efforts targeting the behaviors of these vectors i.e using non-pyrethroids-based indoor residual spraying and spatial repellents outdoors are needed.

DOI: https://doi.org/10.21203/rs.3.rs-2772202/v1
Viruses. 2023 Mar 26. pii: 851. [Epub ahead of print]15(4):

Differences in Longevity and Temperature-Driven Extrinsic Incubation Period Correlate with Varying Dengue Risk in the Arizona-Sonora Desert Region.

Kacey C Ernst, Kathleen R Walker, A Lucia Castro-Luque, Chris Schmidt, Teresa K Joy, Maureen Brophy, Pablo Reyes-Castro, Rolando Enrique Díaz-Caravantes, Veronica Ortiz Encinas, Alfonso Aguilera, Mercedes Gameros, Rosa Elena Cuevas Ruiz, Mary H Hayden, Gerardo Alvarez, Andrew Monaghan, Daniel Williamson, Josh Arnbrister, Eileen Jeffrey Gutiérrez, Yves Carrière, Michael A Riehle.

  Dengue transmission is determined by a complex set of interactions between the environment, Aedes aegypti mosquitoes, dengue viruses, and humans. Emergence in new geographic areas can be unpredictable, with some regions having established mosquito populations for decades without locally acquired transmission. Key factors such as mosquito longevity, temperature-driven extrinsic incubation period (EIP), and vector-human contact can strongly influence the potential for disease transmission. To assess how these factors interact at the edge of the geographical range of dengue virus transmission, we conducted mosquito sampling in multiple urban areas located throughout the Arizona-Sonora desert region during the summer rainy seasons from 2013 to 2015. Mosquito population age structure, reflecting mosquito survivorship, was measured using a combination of parity analysis and relative gene expression of an age-related gene, SCP-1. Bloodmeal analysis was conducted on field collected blood-fed mosquitoes. Site-specific temperature was used to estimate the EIP, and this predicted EIP combined with mosquito age were combined to estimate the abundance of "potential" vectors (i.e., mosquitoes old enough to survive the EIP). Comparisons were made across cities by month and year. The dengue endemic cities Hermosillo and Ciudad Obregon, both in the state of Sonora, Mexico, had higher abundance of potential vectors than non-endemic Nogales, Sonora, Mexico. Interestingly, Tucson, Arizona consistently had a higher estimated abundance of potential vectors than dengue endemic regions of Sonora, Mexico. There were no observed city-level differences in species composition of blood meals. Combined, these data offer insights into the critical factors required for dengue transmission at the ecological edge of the mosquito's range. However, further research is needed to integrate an understanding of how social and additional environmental factors constrain and enhance dengue transmission in emerging regions.

Keywords:  Aedes aegypti; Mexico; age-grading; climate; dengue; extrinsic incubation period; longevity; mosquito; parity

DOI:  https://doi.org/10.3390/v15040851
Trop Med Infect Dis. 2023 Apr 03. pii: 215. [Epub ahead of print]8(4):

A Multi-Species Simulation of Mosquito Disease Vector Development in Temperate Australian Tidal Wetlands Using Publicly Available Data.

Kerry Staples, Steven Richardson, Peter J Neville, Jacques Oosthuizen.

  Worldwide, mosquito monitoring and control programs consume large amounts of resources in the effort to minimise mosquito-borne disease incidence. On-site larval monitoring is highly effective but time consuming. A number of mechanistic models of mosquito development have been developed to reduce the reliance on larval monitoring, but none for Ross River virus, the most commonly occurring mosquito-borne disease in Australia. This research modifies existing mechanistic models for malaria vectors and applies it to a wetland field site in Southwest, Western Australia. Environmental monitoring data were applied to an enzyme kinetic model of larval mosquito development to simulate timing of adult emergence and relative population abundance of three mosquito vectors of the Ross River virus for the period of 2018-2020. The model results were compared with field measured adult mosquitoes trapped using carbon dioxide light traps. The model showed different patterns of emergence for the three mosquito species, capturing inter-seasonal and inter-year variation, and correlated well with field adult trapping data. The model provides a useful tool to investigate the effects of different weather and environmental variables on larval and adult mosquito development and can be used to investigate the possible effects of changes to short-term and long-term sea level and climate changes.

Keywords:  Aedes camptorhynchus; Aedes vigilax; Culex annulirostris; larval mosquito development; mathematical modelling; temperature-dependent development; vector modelling

DOI:  https://doi.org/10.3390/tropicalmed8040215
PLoS One. 2023 ;18(4): e0284247

Increased malaria incidence following irrigation practices in the Endorheic Rift Valley Basin of Sidama Region, Ethiopia.

Dawit Hawaria, Solomon Kibret.

BACKGROUND: Water resource development practice such as irrigation is key to ensuring economic growth and food security in developing countries. However, unintended public health problems such as malaria linked to such development projects have been a concern. This study aimed to determine the impact of irrigation on malaria incidence and vector mosquito abundance in southern Ethiopia.METHODS: Eight years' malaria morbidity data were extracted from the medical registers of health facilities in both irrigated and non-irrigated settings. Additionally, adult and larval malaria vector surveys were carried out in both irrigated and non-irrigated villages. The trend of malaria incidence, case distribution across age and sex, seasonality, parasite species proportion, and mosquito density were analyzed and compared between irrigated and non-irrigated villages.
RESULTS: The result showed that annual mean malaria incidence was 6.3 higher in the irrigated (95% CI: 0.7-33.6) than in the non-irrigated villages (95% CI: 1.2-20.6). Although a remarkable declining trend in malaria incidence was observed for four successive years (2013-2017), a significant resurgence between 2018 and 2020 was noted following the introduction of irrigation schemes. The densities of adult Anopheles mosquitoes were 15-fold higher in the irrigated compared to non-irrigated villages. Of the total potential mosquito-breeding habitats surveyed, the majority (93%) were from irrigated villages.
CONCLUSION: Higher malaria incidence, adult Anopheles density, and mosquito-breeding habitat were recorded in the irrigated villages compared to non-irrigated villages. These observations have important implications for the effectiveness of existing malaria interventions. Environmental management could help reduce the breeding of malaria vector mosquitoes around irrigation schemes.

DOI: https://doi.org/10.1371/journal.pone.0284247
PLoS Negl Trop Dis. 2023 Apr 27. 17(4): e0011237

Potential risk sites and their relationship with dengue cases, Campinas municipality, Southeast Brazil.

Jessica Andretta Mendes, Sophie O Vanwambeke.

BACKGROUND: Among the main activities of dengue and vector control recommended by the Ministry of Health of Brazil is the inspection and monitoring of properties identified as Strategic Points (SPs) and Special Buildings (SBs). SPs are properties associated to hazard, where there is a concentration of suitable egg-laying containers for Aedes aegypti mosquitoes, while SBs have greater importance for human exposure to the dengue virus.OBJECTIVES: To investigate the effect of characteristics of the urban landscape on dengue incidence. Specifically, we tested if SPs and SBs affect dengue case distribution in Campinas, and if they do, if they affect the risk differently. We considered the period from 2013 to 2016.
METHODS: We tested whether dengue cases were more numerous than expected in the vicinity of SPs and SBs, putative sources of risk, using the Negative Binomial models. We also tested the existence of a gradient in incidence with increasing distance to SPs and SBs by using Stone's test.
RESULTS: The Rate Ratios (RR) values were always higher closer to the SPs and SBs, and these values tended to decrease as distance from these sources increased. In general, RR values greater than one, which indicates a higher risk, were associated to the closest buffers from the SPs/SBs properties, until nearly 550 meters for the SPs and 650 meters for the SBs. Stone's test results indicated that for all years considered, there was a correlation between the distance from the SPs/SBs and dengue cases occurrences, except for SBs from 2016. For SPs the relationship is stronger than for SBs.
DISCUSSION: Results are coherent with other studies which found that these properties contribute to an increased risk of dengue transmission. We emphasize the importance of public agents' survey work and the importance to keep and improve the inspections in SPs/SBs recorded in Campinas.

DOI: https://doi.org/10.1371/journal.pntd.0011237
PLoS Comput Biol. 2023 Apr 27. 19(4): e1010424

Fusing an agent-based model of mosquito population dynamics with a statistical reconstruction of spatio-temporal abundance patterns.

Sean M Cavany, Guido España, Alun L Lloyd, Gonzalo M Vazquez-Prokopec, Helvio Astete, Lance A Waller, Uriel Kitron, Thomas W Scott, Amy C Morrison, Robert C Reiner, T Alex Perkins.

The mosquito Aedes aegypti is the vector of a number of medically-important viruses, including dengue virus, yellow fever virus, chikungunya virus, and Zika virus, and as such vector control is a key approach to managing the diseases they cause. Understanding the impact of vector control on these diseases is aided by first understanding its impact on Ae. aegypti population dynamics. A number of detail-rich models have been developed to couple the dynamics of the immature and adult stages of Ae. aegypti. The numerous assumptions of these models enable them to realistically characterize impacts of mosquito control, but they also constrain the ability of such models to reproduce empirical patterns that do not conform to the models' behavior. In contrast, statistical models afford sufficient flexibility to extract nuanced signals from noisy data, yet they have limited ability to make predictions about impacts of mosquito control on disease caused by pathogens that the mosquitoes transmit without extensive data on mosquitoes and disease. Here, we demonstrate how the differing strengths of mechanistic realism and statistical flexibility can be fused into a single model. Our analysis utilizes data from 176,352 household-level Ae. aegypti aspirator collections conducted during 1999-2011 in Iquitos, Peru. The key step in our approach is to calibrate a single parameter of the model to spatio-temporal abundance patterns predicted by a generalized additive model (GAM). In effect, this calibrated parameter absorbs residual variation in the abundance time-series not captured by other features of the mechanistic model. We then used this calibrated parameter and the literature-derived parameters in the agent-based model to explore Ae. aegypti population dynamics and the impact of insecticide spraying to kill adult mosquitoes. The baseline abundance predicted by the agent-based model closely matched that predicted by the GAM. Following spraying, the agent-based model predicted that mosquito abundance rebounds within about two months, commensurate with recent experimental data from Iquitos. Our approach was able to accurately reproduce abundance patterns in Iquitos and produce a realistic response to adulticide spraying, while retaining sufficient flexibility to be applied across a range of settings.

DOI: https://doi.org/10.1371/journal.pcbi.1010424
Acta Trop. 2023 Apr 20. pii: S0001-706X(23)00116-X. [Epub ahead of print] 106929

Northern and Central Chile still free of emerging flaviviruses in mosquitoes (Diptera: Culicidae).

Beatriz Cancino-Faure, Christian R González, Alejandro Piñeiro González, Marcela Salazar-Viedma, Luis Pastenes, Elizabeth Valdés, Camila Bustos, Rafael Lozada-Yavina, Mauricio Canals.

  Geographic isolation and strict control limits in border areas have kept Chile free from various pathogens, including Flavivirus. However, the scenario is changing mainly due to climate change, the reintroduction of more aggressive mosquitoes, and the great wave of migration of people from endemic countries in recent years. Hence, it is necessary to surveillance mosquitoes to anticipate a possible outbreak in the population and take action to control it. This study aimed to investigate the presence of Flavivirus RNA by molecular tools with consensus primers in mosquitoes collected in the extreme north and central Chile. From 2019 to 2021, a prospective study was carried out in localities of Northern and part of Central Chile. Larvae, pupae, and adults of mosquitoes were collected in rural and urban sites in each locality. The collected samples were pooled by species and geographical location and tested using RT-PCR and RT-qPCR to determine presence of Flavivirus. 3085 specimens were collected, the most abundant specie Culex quinquefasciatus in the North and Aedes (Ochlerotatus) albifasciatus in the Center of Chile. Both genera are associated with Flavivirus transmission. However, PCR and RT-PCR did not detect Flavivirus RNA in the mosquitoes studied. These negative results indicate we are still a free Flavivirus country, which is reaffirmed by the non-existence of endemic human cases. Despite this, routine surveillance of mosquitoes and the pathogens they carry is highly recommended to evaluate each area-specific risk of vector-borne transmission.

Keywords:  Climate change; Flaviviridae; RT-qPCR; arbovirus; mosquito-borne disease

DOI:  https://doi.org/10.1016/j.actatropica.2023.106929
MMWR Morb Mortal Wkly Rep. 2023 Apr 28. 72(17): 452-457

Unprecedented Outbreak of West Nile Virus - Maricopa County, Arizona, 2021.

Melissa Kretschmer, Irene Ruberto, John Townsend, Karen Zabel, James Will, Keila Maldonado, Nicole Busser, Dan Damian, Ariella P Dale.

West Nile virus (WNV) is a mosquitoborne disease primarily transmitted through bites of infected Culex species mosquitos (1). In the United States, WNV is the leading domestically acquired arboviral disease; it can cause severe illness affecting the brain and spinal cord with an associated case fatality rate of 10% (2,3). On September 2, 2021, Maricopa County Environmental Services Department, Vector Control Division (MCESD-VCD) notified the Maricopa County Department of Public Health (MCDPH) and the Arizona Department of Health Services (ADHS) that the WNV vector index (VI), a measure of infected Culex mosquitoes, was substantially elevated. By that date, at least 100 WNV cases had already been reported among Maricopa County residents to MCDPH by health care providers and laboratories. Within 2 weeks, the VI reached its highest ever recorded level (53.61), with an associated tenfold increase in the number of human disease cases. During 2021, a total of 1,487 human WNV cases were identified; 956 (64.3%) patients had neuroinvasive disease, and 101 (6.8%) died. MCESD-VCD conducted daily remediation efforts to mitigate elevated VI and address mosquito-related complaints from residents (i.e., large numbers of outdoor mosquitoes from an unknown source and unmaintained swimming pools potentially breeding mosquitoes). MCDPH increased outreach to the community and providers through messaging, education events, and media. This was the largest documented focal WNV outbreak in a single county in the United States (4). Despite outreach efforts to communities and health care partners, clinicians and patients reported a lack of awareness of the WNV outbreak, highlighting the need for public health agencies to increase prevention messaging to broaden public awareness and to ensure that health care providers are aware of recommended testing methods for clinically compatible illnesses.

DOI: https://doi.org/10.15585/mmwr.mm7217a1
Viruses. 2023 Apr 21. pii: 1019. [Epub ahead of print]15(4):

Vector Competence of Aedes albopictus for Yellow Fever Virus: Risk of Reemergence of Urban Yellow Fever in Brazil.

Rossela Damasceno-Caldeira, Joaquim Pinto Nunes-Neto, Carine Fortes Aragão, Maria Nazaré Oliveira Freitas, Milene Silveira Ferreira, Paulo Henrique Gomes de Castro, Daniel Damous Dias, Pedro Arthur da Silva Araújo, Roberto Carlos Feitosa Brandão, Bruno Tardelli Diniz Nunes, Eliana Vieira Pinto da Silva, Lívia Carício Martins, Pedro Fernando da Costa Vasconcelos, Ana Cecília Ribeiro Cruz.

  The risk of the emergence and reemergence of zoonoses is high in regions that are under the strong influence of anthropogenic actions, as they contribute to the risk of vector disease transmission. Yellow fever (YF) is among the main pathogenic arboviral diseases in the world, and the Culicidae Aedes albopictus has been proposed as having the potential to transmit the yellow fever virus (YFV). This mosquito inhabits both urban and wild environments, and under experimental conditions, it has been shown to be susceptible to infection by YFV. In this study, the vector competence of the mosquito Ae. albopictus for the YFV was investigated. Female Ae. albopictus were exposed to non-human primates (NHP) of the genus Callithrix infected with YFV via a needle inoculation. Subsequently, on the 14th and 21st days post-infection, the legs, heads, thorax/abdomen and saliva of the arthropods were collected and analyzed by viral isolation and molecular analysis techniques to verify the infection, dissemination and transmission. The presence of YFV was detected in the saliva samples through viral isolation and in the head, thorax/abdomen and legs both by viral isolation and by molecular detection. The susceptibility of Ae. albopictus to YFV confers a potential risk of reemergence of urban YF in Brazil.

Keywords:  Aedes albopictus; RT–qPCR; experimental infection; reemergence; viral isolation; yellow fever

DOI:  https://doi.org/10.3390/v15041019
Parasit Vectors. 2023 Apr 24. 16(1): 140

Report of natural Mayaro virus infection in Mansonia humeralis (Dyar & Knab, Diptera: Culicidae).

Flávia Barreto De Sousa, Juliana Santana de Curcio, Lívia do Carmo Silva, Diego Michel Fernandes da Silva, Silvia Maria Salem-Izacc, Carlos Eduardo Anunciação, Bergmann Morais Ribeiro, Marco Tulio A Garcia-Zapata, Elisângela de Paula Silveira-Lacerda.

  BACKGROUND: Arboviruses are a group of viruses transmitted to vertebrate hosts by certain blood-feeding arthropods. Among urban vectors of arboviruses, mosquitoes of the genus Aedes are the most common. However, other mosquitoes may be susceptible to infection and involved in the transmission, such as Mansonia spp. Therefore, this study aimed to investigate whether Mansonia humeralis can be infected with the Mayaro virus (MAYV).METHODS: These insects were collected from 2018 to 2020 in chicken coops of rural communities in Jaci Paraná in Porto Velho, Rondônia, Brazil, while performing blood-feeding on roosters. The mosquitoes were randomly grouped in pools from which the head and thorax were macerated and checked for the presence of MAYV by quantitative reverse transcription polymerase chain reaction (RT-qPCR). The positive pools were used to infect the C6/36 cell line, and on different days post-infection, the supernatant of the infected cells was subjected to viral detection by RT-qPCR.
RESULTS: A total of 183 pools of female mosquitoes were tested, of which 18% were positive for MAYV; some samples from insect pools inoculated into C6/36 cells showed in vitro multiplication capacity between 3 and 7 days post-infection.
CONCLUSIONS: This is the first report of Ma. humeralis mosquitoes that are naturally infected by MAYV, indicating that these vectors may be potential transmitting agents of this arbovirus.

Keywords:  Arboviruses; Mansonia humeralis; Mayaro fever; Viral isolation

DOI:  https://doi.org/10.1186/s13071-023-05707-2
Trop Med Infect Dis. 2023 Apr 06. pii: 217. [Epub ahead of print]8(4):

Vector Competence of Culex quinquefasciatus from Brazil for West Nile Virus.

Lúcia Aline Moura Reis, Eliana Vieira Pinto da Silva, Daniel Damous Dias, Maria Nazaré Oliveira Freitas, Rossela Damasceno Caldeira, Pedro Arthur da Silva Araújo, Fábio Silva da Silva, José Wilson Rosa Junior, Roberto Carlos Feitosa Brandão, Bruna Laís Sena do Nascimento, Lívia Caricio Martins, Joaquim Pinto Nunes Neto.

  West Nile virus is characterized as a neurotropic pathogen, which can cause West Nile fever and is transmitted by mosquitoes of the genus Culex. In 2018, the Instituto Evandro Chagas performed the first isolation of a WNV strain in Brazil from a horse brain sample. The present study aimed to evaluate the susceptibility of orally infected Cx. quinquefasciatus from the Amazon region of Brazil to become infected and transmit the WNV strain isolated in 2018. Oral infection was performed with blood meal artificially infected with WNV, followed by analysis of infection, dissemination, and transmission rates, as well as viral titers of body, head, and saliva samples. At the 21st dpi, the infection rate was 100%, the dissemination rate was 80%, and the transmission rate was 77%. These results indicate that Cx. quinquefasciatus is susceptible to oral infection by the Brazilian strain of WNV and may act as a possible vector of the virus since it was detected in saliva from the 21st dpi.

Keywords:  Culex quinquefasciatus; West Nile virus; arbovirus infections; flavivirus

DOI:  https://doi.org/10.3390/tropicalmed8040217
Trop Med Infect Dis. 2023 Apr 20. pii: 237. [Epub ahead of print]8(4):

First Isolation and Genome Sequence Analysis of West Nile Virus in Mosquitoes in Brazil.

Joaquim Pinto Nunes Neto, Lúcia Aline Moura Reis, Maria Nazaré Oliveira Freitas, Bruna Laís Sena do Nascimento, Liliane Leal das Chagas, Hernan Hermes Monteiro da Costa, Jéssica Cecília Pinheiro Rodrigues, Camila Margalho Braga, Eliana Vieira Pinto da Silva, Sandro Patroca Silva, Lívia Caricio Martins.

  West Nile virus is a flavivirus transmitted by mosquitoes, mainly of the genus Culex. In Brazil, serological studies have already indicated the circulation of the virus since 2003, with the first human case detected in 2014. The objective of the present paper is to report the first isolation of WNV in a Culex (Melanoconion) mosquito. Arthropods were collected by protected human attraction and CDC light bait, and taxonomically identified and analyzed by viral isolation, complement fixation and genomic sequencing tests. WNV was isolated from samples of Culex (Melanoconion) mosquitoes, and the sequencing analysis demonstrated that the isolated strain belonged to lineage 1a. The finding of the present study presents the first evidence of the isolation and genome sequencing of WNV in arthropods in Brazil.

Keywords:  Culex; Culicidae; West Nile virus infection; disease vectors

DOI:  https://doi.org/10.3390/tropicalmed8040237
Environ Health Perspect. 2023 Apr;131(4): 47016

Assessing the Influence of Climate on the Spatial Pattern of West Nile Virus Incidence in the United States.

Morgan E Gorris, James T Randerson, Shane R Coffield, Kathleen K Treseder, Charles S Zender, Chonggang Xu, Carrie A Manore.

BACKGROUND: West Nile virus (WNV) is the leading cause of mosquito-borne disease in humans in the United States. Since the introduction of the disease in 1999, incidence levels have stabilized in many regions, allowing for analysis of climate conditions that shape the spatial structure of disease incidence.OBJECTIVES: Our goal was to identify the seasonal climate variables that influence the spatial extent and magnitude of WNV incidence in humans.
METHODS: We developed a predictive model of contemporary mean annual WNV incidence using U.S. county-level case reports from 2005 to 2019 and seasonally averaged climate variables. We used a random forest model that had an out-of-sample model performance of R2=0.61.
RESULTS: Our model accurately captured the V-shaped area of higher WNV incidence that extends from states on the Canadian border south through the middle of the Great Plains. It also captured a region of moderate WNV incidence in the southern Mississippi Valley. The highest levels of WNV incidence were in regions with dry and cold winters and wet and mild summers. The random forest model classified counties with average winter precipitation levels <23.3mm/month as having incidence levels over 11 times greater than those of counties that are wetter. Among the climate predictors, winter precipitation, fall precipitation, and winter temperature were the three most important predictive variables.
DISCUSSION: We consider which aspects of the WNV transmission cycle climate conditions may benefit the most and argued that dry and cold winters are climate conditions optimal for the mosquito species key to amplifying WNV transmission. Our statistical model may be useful in projecting shifts in WNV risk in response to climate change. https://doi.org/10.1289/EHP10986.

DOI: https://doi.org/10.1289/EHP10986
Insects. 2023 Apr 11. pii: 373. [Epub ahead of print]14(4):

Spatial Distribution and Long-Term Persistence of Wolbachia-Infected Aedes aegypti in the Mentari Court, Malaysia.

Yoon Ling Cheong, Wasi A Nazni, Han Lim Lee, Ahmad NoorAfizah, Ibrahim C MohdKhairuddin, Ghazali M R Kamarul, Nasir M N Nizam, Mohd A K Arif, Zabari M NurZatilAqmar, Saidin M Irwan, Khairuddin Khadijah, Yusof M Paid, Omar Topek, Asim H Hasnor, Rahman AbuBakar, Balvinder Singh Gill, Kamaludin Fadzilah, Aris Tahir, Steven P Sinkins, Ary A Hoffmann.

  Dengue is endemic in Malaysia, and vector control strategies are vital to reduce dengue transmission. The Wolbachia strain wAlbB carried by both sexes of Ae. aegypti was released in Mentari Court, a high-rise residential site, in October 2017 and stopped after 20 weeks. Wolbachia frequencies are still being monitored at multiple traps across this site, providing an opportunity to examine the spatiotemporal distribution of Wolbachia and mosquito density with respect to year, residential block, and floor, using spatial interpolation in ArcGIS, GLMs, and contingency analyses. In just 12 weeks, Wolbachia-infected mosquitoes were established right across the Mentari Court site with an overall infection frequency of >90%. To date, the Wolbachia frequency of Ae. aegypti has remained high in all areas across the site despite releases finishing four years ago. Nevertheless, the Wolbachia invaded more rapidly in some residential blocks than others, and also showed a relatively higher frequency on the eighth floor. The Ae. aegypti index tended to differ somewhat between residential blocks, whilst the Ae. albopictus index was relatively higher at the top and bottom floors of buildings. In Mentari Court, only a short release period was required to infiltrate Wolbachia completely and stably into the natural population. The results inform future releases in comparable sites in a dengue control programme.

Keywords:  Ae. aegypti; Wolbachia; invasion; ovitrap index; spatial interpolation

DOI:  https://doi.org/10.3390/insects14040373