bims-mosdis 2022-04-10 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2022‒04‒10
twenty papers selected by
Richard Halfpenny
Staffordshire University

Extensive public health initiatives drive the elimination of Aedes aegypti (Diptera, Culicidae) from a town in regional Queensland: A case study from Gin Gin, Australia.
Co-distribution of dengue and Chikungunya viruses in Aedes mosquitoes of Delhi, India.
Prevalence and transmission potential of Wolbachia in Aedes albopictus population circulating in endemic coastal districts of Odisha, India.
Risk assessment of urban yellow fever virus transmission in Kenya: is Aedes aegypti an efficient vector?
Current status of malaria elimination in Koraput district of Odisha, India.
Insecticide susceptibility status of malaria vectors, Anopheles culicifacies, Anopheles fluviatilis and Anopheles minimus in the tribal districts of Jharkhand state of India.
First evidence of pyrethroid resistance in Italian populations of West Nile virus vector Culex pipiens.
Evaluation of the protective efficacy of a spatial repellent to reduce malaria incidence in children in Mali compared to placebo: study protocol for a cluster-randomized double-blinded control trial (the AEGIS program).
Myzorhynchus series of Anopheles mosquitoes as potential vectors of Plasmodium bubalis in Thailand.
Evaluation of the protective efficacy of a spatial repellent to reduce malaria incidence in children in western Kenya compared to placebo: study protocol for a cluster-randomized double-blinded control trial (the AEGIS program).
Coupled small molecules target RNA interference and JAK/STAT signaling to reduce Zika virus infection in Aedes aegypti.
Rediscovering the mosquito fauna (Diptera: Culicidae) of Estonia: an annotated checklist with distribution maps and DNA evidence.
Fitness Cost of Sequential Selection with Deltamethrin in Aedes aegypti (Diptera: Culicidae).
First Detection of the Invasive Mosquito Vector Aedes albopictus (Diptera: Culicidae) in Benin, West Africa, 2021.
Five-Year Trend Analysis of Malaria Cases in East Shawa Zone, Ethiopia.
Dengue and Dengue Virus in Guangdong, China, 1978-2017: Epidemiology, Seroprevalence, Evolution, and Policies.
West Nile and Usutu virus seroprevalence in Hungary: A nationwide serosurvey among blood donors in 2019.
Reaching the malaria elimination goal in Brazil: a spatial analysis and time-series study.
Malaria at international borders: challenges for elimination on the remote Brazil-Peru border.
Prevalence and Associated Factors of Malaria Infection among Outpatients Visiting Shewa Robit Health Center, Northcentral Ethiopia.

PLoS Negl Trop Dis. 2022 Apr 08. 16(4): e0010243

Extensive public health initiatives drive the elimination of Aedes aegypti (Diptera, Culicidae) from a town in regional Queensland: A case study from Gin Gin, Australia.

Brendan J Trewin, Brian L Montgomery, Tim P Hurst, Jason S Gilmore, Nancy M Endersby-Harshman, Greg J Crisp.

Aedes aegypti is the primary vector of exotic arboviruses (dengue, chikungunya and Zika) in Australia. Once established across much of Australia, this mosquito species remains prevalent in central and northern Queensland. In 2011, Ae. aegypti was re-discovered in the town of Gin Gin, Queensland, by health authorities during routine larval surveillance. This town is situated on a major highway that provides a distribution pathway into the highly vulnerable and populous region of the state where the species was once common. Following the detection, larval habitat and adult control activities were conducted as a public health intervention to eliminate the Ae. aegypti population and reduce the risk of exotic disease transmission. Importantly, genetic analysis revealed a homogenous cluster and small effective population vulnerable to an elimination strategy. By 2015, adult surveillance revealed the population had expanded throughout the centre of the town. In response, a collaboration between research agencies and local stakeholders activated a second control program in 2016 that included extensive community engagement, enhanced entomologic surveillance and vector control activities including the targeting of key containers, such as unsealed rainwater tanks. Here we describe a model of the public health intervention which successfully reduced the Ae. aegypti population below detection thresholds, using source reduction, insecticides and novel, intensive genetic surveillance methods. This outcome has important implications for future elimination work in small towns in regions sub-optimal for Ae. aegypti presence and reinforces the longstanding benefits of a partnership model for public health-based interventions for invasive urban mosquito species.

DOI: https://doi.org/10.1371/journal.pntd.0010243
J Vector Borne Dis. 2021 Oct-Dec;58(4):58(4): 386-390

Co-distribution of dengue and Chikungunya viruses in Aedes mosquitoes of Delhi, India.

Kumar Vikram, B N Nagpal, Sanjeev Kumar Gupta, N R Tuli, Himmat Singh, Aruna Srivastava, Rekha Saxena.

  BACKGROUND & OBJECTIVES: In India, vector-borne diseases, dengue and chikungunya are major public health concerns. In recent decades, dengue outbreaks have been reported in almost every part of India. In 2016, India recorded 101388 dengue cases and 210 deaths, including 4337 cases and six deaths in Delhi, whereas Chikungunya outbreaks were reported from several states in 2006, with 1.3 million cases. The Dengue virus (DENV) and Chikungunya virus (CHIKV) are both transmitted by the same Aedes mosquito species. DENV and CHIKV co-infections have been reported in 13 of 98 countries, with both viruses being transmitted locally. The reasons for the sudden upsurge in cases of these diseases are undetermined.METHODS: From March to December 2016, a study was carried out in 66 localities of Delhi in collaboration with the Municipal Corporation of Delhi. Localities were selected on the basis of confirmed dengue cases reported during the last five years and the study area was visited once a month. A door-to-door entomological survey was conducted to identify Aedes breeding in all water-filled containers in and around houses. Both immature and mature stages of Aedes mosquitoes were collected. Mosquitoes were pooled (n≤10 each for male and female) breeding site-wise and stored in Trizol at -80°C. The Chikungunya and dengue viruses were detected using a multiplex RT-PCR.
RESULTS: A total of 981 Aedes mosquitos were distributed among 146 Pools, and DENV and CHIKV were detected using Multiplex Reverse Transcriptase-PCR. Chikungunya virus was identified in 19 pools of females captured adults, whereas dengue virus was found in 8 pools of females captured adults. There was no evidence of coinfection in any of the pools.
INTERPRETATION & CONCLUSION: In endemic areas, continuous surveillance for both dengue and Chikungunya viruses is required to identify and characterize these viral pathogens. This information will also help implement effective strategies to combat outbreaks produced by these emerging viral pathogens.

Keywords:  Chikungunya virus; Co-distribution; Coinfection; Dengue virus

DOI:  https://doi.org/10.4103/0972-9062.325638
J Vector Borne Dis. 2021 Oct-Dec;58(4):58(4): 297-305

Prevalence and transmission potential of Wolbachia in Aedes albopictus population circulating in endemic coastal districts of Odisha, India.

Ipsita Mohanty, Animesha Rath, Nitika Pradhan, Barsa Baisalini Panda, Pradyumna Kishore Mohapatra, Rupenangshu Kumar Hazra.

  Wolbachia, known for its reproductive manipulation capabilities in insects, are being implemented to control dengue and chikungunya. To understand Wolbachia biology and its utility as a bio-control for vector mosquito's populations, we investigated its dissemination pattern in field in collected Ae. albopictus along with its maternal transmission efficacy over generations in regions of endemic dengue (DENV) transmission. Field collected Ae. albopictus were subjected to PCR for Wolbachia screening. Overall mean Wolbachia infection frequency in Ae. albopictus was found out to be 87.3% wherein a trend was observed in the pattern of maternal transmission across generations. χ2 for trend revealed a significant variation between Wolbachia infections and non-infections in Ae. albopictus generations. Linear regression analysis revealed the involvement of a strong negative correlation, implying that overall Wolbachia infection tends to decrease in places with high dengue cases.The reduction in Wolbachia infection frequency may be attributed to several environmental factors with the probability of being the cause for endemicity of dengue in the studied areas.This study reports on the transmission efficacy of naturally occurring Wolbachia in successive generations of Ae. albopictus and its correlation with dengue cases in clusters of Odisha, India. Studying the transmission trend of Wolbachia along with transovarial transmission of DENV might be indicative towards the interplay of Wolbachia infection in presence/absence of DENV.

Keywords:  Wolbachia; bio-control; endemic; mono-infection; superinfection; transfection

DOI:  https://doi.org/10.4103/0972-9062.313967
Emerg Microbes Infect. 2022 Apr 07. 1-26

Risk assessment of urban yellow fever virus transmission in Kenya: is Aedes aegypti an efficient vector?

Sheila B Agha, David P Tchouassi, Michael J Turell, Armanda D S Bastos, Rosemary Sang.

  The absence of urban yellow fever epidemics in East Africa remains a mystery amidst the proliferation of Aedes aegypti in this region. To understand the transmission dynamics of the disease, we tested urban (Mombasa, Kisumu, and Nairobi) Aedes mosquito populations in Kenya for their susceptibility to an East African yellow fever virus (YFV) genotype. Overall, 22% (n = 805) of the Ae. aegypti that were orally challenged with an infectious dose of YFV had a midgut infection, with comparable rates for Mombasa and Kisumu (χ2 = 0.35, df = 1, P = 0.55), but significantly lower rates for Nairobi (χ2 > 11.08, df = 1, P < 0.0009). Variations in YFV susceptibility (midgut infection) among Ae. aegypti subspecies were not associated with discernable cytochrome c oxidase subunit 1 gene haplotypes. Remarkably, no YFV dissemination or transmission was observed among the orally challenged Ae. aegypti populations. Moreover, Ae. aegypti mosquitoes that were intrathoracically inoculated with YFV failed to transmit the virus via capillary feeding. In contrast, dissemination (oral exposure) and transmission (intrathoracic inoculation) of YFV was observed among a few peri-domestic Ae. bromeliae mosquitoes (n = 129) that were assessed from these urban areas. Our study highlights an inefficient urban Ae. aegypti population, and the potential for Ae. bromeliae in sustaining an urban YFV transmission in Kenya. An assessment of urban Ae. aegypti susceptibility to other YFV genotypes, and vector potential of urban Ae. bromeliae populations in Kenya is recommended to guide cost-effective vaccination.

Keywords:  Aedes aegypti; Aedes bromeliae; East Africa; transmission barrier; urbanization; vector competence; yellow fever virus

DOI:  https://doi.org/10.1080/22221751.2022.2063762
J Vector Borne Dis. 2021 Oct-Dec;58(4):58(4): 317-322

Current status of malaria elimination in Koraput district of Odisha, India.

Sudhansu Sekhar Sahu, Sonia Thankachy, Smrutidhara Dash, Dilip Kumar Panigrahi, Ashwani Kumar, Kabir Kumar Swain.

  BACKGROUND & OBJECTIVES: After launching of NFME and NSP with wide scale implementation of effective intervention tools during 2017, Odisha State of India observed a drastic reduction of malaria cases (81%) in 2018 and 88.6% in 2019, compared to 2017. The current study analysed the different factors causative for malaria reduction in Koraput district of Odisha State, India.METHODS: The vector density and malaria incidences were assessed from January 2016 to December 2019 and human blood index, bio-efficacy and use rate of LLINs were assessed after distribution of long-lasting insecticidal nets.
RESULTS: The use rate of LLINs by the villagers ranged from 93.8% to 100% throughout the year. The mortality of Anopheles jeyporiensis remained 100.0% in both DuraNet and PermaNet LNs. The density of An. fluviatilis after distribution of LLINs reduced from 4.7 to 0.0 whereas, the density of An. culicifacies reduced from 12.2 to 9.3. The HBI of An. fluviatilis and An. culicifacies was 0.006 and 0.005, respectively after distribution of LLINs. The malaria incidences also drop from 14.2 to zero after distribution.
INTERPRETATION & CONCLUSION: A significant reduction in malaria incidences was validated and the possible reasons for the reduction are discussed.

Keywords:  Annual parasite incidence; DAMaN; Koraput; Malaria elimination

DOI:  https://doi.org/10.4103/0972-9062.325644
J Vector Borne Dis. 2021 Oct-Dec;58(4):58(4): 374-382

Insecticide susceptibility status of malaria vectors, Anopheles culicifacies, Anopheles fluviatilis and Anopheles minimus in the tribal districts of Jharkhand state of India.

M K Das, Manju Rahi, R C Dhiman, K Raghavendra.

  BACKGROUND AND OBJECTIVES: Insecticide resistance in malaria vectors has been a major challenge to vector control programs and updated information to the commonly used insecticides is essential for planning appropriate vector control measures. Anopheles culicifacies and An. fluviatilis are the two main vectors prevalent in Jharkhand state of India and role of An. minimus is contemplated in the transmission of malaria in this state. All the districts in the state are predominantly inhabited by the tribal population and are endemic for malaria. A study was undertaken in 12 districts of Jharkhand state to determine the insecticide susceptibility status of the 3 prevalent primary vector species, An. culicifacies, An. fluviatilis, and An. minimus.METHODS: Wild-caught adult female An. culicifacies, An. fluviatilis, and An. minimus, mosquitoes were collected from stratified ecotypes from different localities of 12 tribal districts of Jharkhand state during 2018 and 2019. Susceptibility tube tests were conducted following the WHO method using test kits. Mosquitoes were exposed to WHO impregnated papers with the prescribed discriminatory dosages of DDT - 4%, malathion - 5%, deltamethrin - 0.05%, permethrin - 0.75%, cyfluthrin - 0.15% and lambda cyhalothrin - 0.05%.
RESULTS: Results indicated that An. culicifacies has developed multiple insecticide resistance in all the 12 districts of Jharkhand state. An. fluviatilis was reported resistant for the first time to DDT in all the districts but was susceptible to malathion, deltamethrin, and permethrin whereas in one district it showed possible resistance to malathion. An. minimus was studied in Noamundi CHC of West Singhbhum district, showed possible resistance against DDT but was susceptible to malathion, deltamethrin, and permethrin.
INTERPRETATION & CONCLUSION: The development of multiple insecticide resistance in An. culicifacies including to pyrethroids, has been a concern for malaria control programmes for effective vector management but a report of resistance to DDT for the first time in An. fluviatlis in all the districts in the state is alarming, An. minimus was found in possible resistance category to DDT in one district and both the species were reported susceptible to malathion, deltamethrin, and permethrin. The result of the present study indicates a need for regular monitoring to assess the insecticide susceptibility to formulate effective vector control measures and resistance management.

Keywords:  ; An. culicifacies; An. fluviatilis; An. minimus; insecticide resistance; vector control

DOI:  https://doi.org/10.4103/0972-9062.325641
Med Vet Entomol. 2022 Apr 09.

First evidence of pyrethroid resistance in Italian populations of West Nile virus vector Culex pipiens.

Verena Pichler, Carola Giammarioli, Romeo Bellini, Rodolfo Veronesi, Daniele Arnoldi, Annapaola Rizzoli, Riccardo Paolo Lia, Domenico Otranto, Marco Ballardini, Pietro Cobre, Paola Serini, Alessandra Della Torre, Beniamino Caputo.

  Culex pipiens (Linnaeus), one of the most abundant mosquito species in Europe, plays a crucial role in the endemic transmission of West Nile virus and caused the large outbreak with >1600 human cases in 2018. Although evidence of resistance to pyrethroids has been reported for Cx. pipiens populations from Spain and Greece, resistance monitoring has been largely neglected in Italy. Herein, we investigate susceptibility of Italian Cx. pipiens populations to the pyrethroids permethrin and deltamethrin. Results from WHO-tube-bioassays revealed mortalities ranging from 14-54%, indicating high levels of resistance, in four out of 10 populations exposed to permethrin (0.75%) and of 63% in one of three populations exposed to deltamethrin (0.05%). Reduced susceptibility (mortality<98%) was detected in almost all other populations. A clear association is shown between the resistant phenotype and the presence of kdr-alleles in position 1014 of the VSSC, strongly suggesting its role in reducing susceptibility. The study provides the first evidence of pyrethroid-resistance in Italian Cx. pipiens populations and reports levels of resistance paralleled in the European region only in Turkey. This highlights the urgent need to implement insecticide-resistance management plans to restore the efficacy of the nowadays only chemical weapon available to control arbovirus transmission in Europe.

Keywords:  Culex pipiens; Europe; insecticide resistance; pest management; vector control

DOI:  https://doi.org/10.1111/mve.12573
Trials. 2022 Apr 05. 23(1): 259

Evaluation of the protective efficacy of a spatial repellent to reduce malaria incidence in children in Mali compared to placebo: study protocol for a cluster-randomized double-blinded control trial (the AEGIS program).

Suzanne Van Hulle, Issaka Sagara, Momar Mbodji, Ghislain Ismael Nana, Mamadou Coulibaly, Alassane Dicko, Mamady Kone, Ismaila Thera, Daman Sylla, Mamadou Diango Traore, Fang Liu, John P Grieco, Nicole L Achee.

  BACKGROUND: Spatial repellents have been widely used for the prevention of mosquito bites but their efficacy in reducing mosquito-borne diseases has never been evaluated in Africa. Additionally, spatial repellents have the potential of being critical tools in the prevention of mosquito-borne diseases in contexts where typical vectors control efforts such as insecticide-treated nets (ITNs) and indoor residual spray (IRS) are inaccessible or underutilized such as among displaced populations or in emergency relief settings. To address this knowledge gap, Kolondieba District, Sikasso Region, Mali was selected as a site to estimate the impact of the Mosquito Shield™, a spatial repellent that incorporates transfluthrin on a plastic sheet, on malaria-related outcomes. Over the past decade, the Region of Sikasso, Health districts of Kadiolo, Yorosso, and Kolondieba have remained among the most afflicted, characterized by an annual parasite incidence of more than 116 cases per 1000 population [1] and a Plasmodium falciparum prevalence rate of 29.7% [2].METHODS: Cluster-randomized, placebo-controlled, double-blinded clinical trial, whereby children ≥ 6 months to < 10 years old will be enrolled and followed to determine the time to malaria infection with monthly blood samples for microscopic diagnosis. A total of 1920 subjects (HHs) will be enrolled in 60 clusters (30 spatial repellent, 30 placebo). Malaria incidence will be estimated and compared to demonstrate and quantify the protective efficacy (PE) of a spatial repellent, in reducing malaria infection. Monthly mosquito collections using CDC light traps will be conducted to determine if there are entomological correlates of spatial repellent efficacy that may be useful for the evaluation of new spatial repellents. Quarterly human landing catches (HLC) will assess the behavioral effects of the intervention.
DISCUSSION: Findings will serve as an efficacy trial of spatial repellent products for sub-Saharan Africa. Findings will be submitted to the World Health Organization Vector Control Advisory Group (WHO VCAG) for assessment of whether spatial repellents have "public health value." Entomological outcomes will also be measured as proxies of malaria transmission to help develop guidelines for the evaluation of future spatial repellent products.
TRIAL REGISTRATION: ClinicalTrials.gov NCT04795648 . Registered on March 12, 2021.

Keywords:  Cluster randomized controlled trial; Malaria; Mali; Spatial repellent; Transfluthrin

DOI:  https://doi.org/10.1186/s13063-022-06197-w
Sci Rep. 2022 Apr 06. 12(1): 5747

Myzorhynchus series of Anopheles mosquitoes as potential vectors of Plasmodium bubalis in Thailand.

Yudhi Ratna Nugraheni, Apinya Arnuphapprasert, Trang Thuy Nguyen, Duriyang Narapakdeesakul, Hoang Lan Anh Nguyen, Juthathip Poofery, Osamu Kaneko, Masahito Asada, Morakot Kaewthamasorn.

Ungulate malaria parasites and their vectors are among the least studied when compared to other medically important species. As a result, a thorough understanding of ungulate malaria parasites, hosts, and mosquito vectors has been lacking, necessitating additional research efforts. This study aimed to identify the vector(s) of Plasmodium bubalis. A total of 187 female mosquitoes (133 Anopheles spp., 24 Culex spp., 24 Aedes spp., and 6 Mansonia spp. collected from a buffalo farm in Thailand where concurrently collected water buffalo samples were examined and we found only Anopheles spp. samples were P. bubalis positive. Molecular identification of anopheline mosquito species was conducted by sequencing of the PCR products targeting cytochrome c oxidase subunit 1 (cox1), cytochrome c oxidase subunit 2 (cox2), and internal transcribed spacer 2 (ITS2) markers. We observed 5 distinct groups of anopheline mosquitoes: Barbirostris, Hyrcanus, Ludlowae, Funestus, and Jamesii groups. The Barbirostris group (Anopheles wejchoochotei or Anopheles campestris) and the Hyrcanus group (Anopheles peditaeniatus) were positive for P. bubalis. Thus, for the first time, our study implicated these anopheline mosquito species as probable vectors of P. bubalis in Thailand.

DOI: https://doi.org/10.1038/s41598-022-09686-9
Trials. 2022 Apr 05. 23(1): 260

Evaluation of the protective efficacy of a spatial repellent to reduce malaria incidence in children in western Kenya compared to placebo: study protocol for a cluster-randomized double-blinded control trial (the AEGIS program).

Eric O Ochomo, John E Gimnig, Achuyt Bhattarai, Aaron M Samuels, Simon Kariuki, George Okello, Bernard Abong'o, Eunice A Ouma, Jackline Kosgei, Stephen Munga, Kiambo Njagi, Wycliffe Odongo, Fang Liu, John P Grieco, Nicole L Achee.

  BACKGROUND: Spatial repellents are widely used for prevention of mosquito bites and evidence is building on their public health value, but their efficacy against malaria incidence has never been evaluated in Africa. To address this knowledge gap, a trial to evaluate the efficacy of Mosquito Shield™, a spatial repellent incorporating transfluthrin, was developed for implementation in Busia County, western Kenya where long-lasting insecticidal net coverage is high and baseline malaria transmission is moderate to high year-round.METHODS: This trial is designed as a cluster-randomized, placebo-controlled, double-blinded clinical trial. Sixty clusters will be randomly assigned in a 1:1 ratio to receive spatial repellent or placebo. A total of 6120 children aged ≥6 months to 10 years of age will be randomly selected from the study clusters, enrolled into an active cohort (baseline, cohort 1, and cohort 2), and sampled monthly to determine time to first infection by smear microscopy. Each cohort following the implementation of the intervention will be split into two groups, one to estimate direct effect of the spatial repellent and the other to estimate degree of diversion of mosquitoes and malaria transmission to unprotected persons. Malaria incidence in each cohort will be estimated and compared (primary indicator) to determine benefit of using a spatial repellent in a high, year-round malaria transmission setting. Mosquitoes will be collected monthly using CDC light traps to determine if there are entomological correlates of spatial repellent efficacy that may be useful for the evaluation of new spatial repellents. Quarterly human landing catches will assess behavioral effects of the intervention.
DISCUSSION: Findings will serve as the first cluster-randomized controlled trial powered to detect spatial repellent efficacy to reduce malaria in sub-Saharan Africa where transmission rates are high, insecticide-treated nets are widely deployed, and mosquitoes are resistant to insecticides. Results will be submitted to the World Health Organization Vector Control Advisory Group for assessment of public health value towards an endorsement to recommend inclusion of spatial repellents in malaria control programs.
TRIAL REGISTRATION: ClinicalTrials.gov NCT04766879 . Registered February 23, 2021.

Keywords:  Clinical trial; Kenya; Malaria; Spatial repellent; Transfluthrin

DOI:  https://doi.org/10.1186/s13063-022-06196-x
PLoS Pathog. 2022 Apr 04. 18(4): e1010411

Coupled small molecules target RNA interference and JAK/STAT signaling to reduce Zika virus infection in Aedes aegypti.

Chasity E Trammell, Gabriela Ramirez, Irma Sanchez-Vargas, Laura A St Clair, Oshani C Ratnayake, Shirley Luckhart, Rushika Perera, Alan G Goodman.

The recent global Zika epidemics have revealed the significant threat that mosquito-borne viruses pose. There are currently no effective vaccines or prophylactics to prevent Zika virus (ZIKV) infection. Limiting exposure to infected mosquitoes is the best way to reduce disease incidence. Recent studies have focused on targeting mosquito reproduction and immune responses to reduce transmission. Previous work has evaluated the effect of insulin signaling on antiviral JAK/STAT and RNAi in vector mosquitoes. Specifically, insulin-fed mosquitoes resulted in reduced virus replication in an RNAi-independent, ERK-mediated JAK/STAT-dependent mechanism. In this work, we demonstrate that targeting insulin signaling through the repurposing of small molecule drugs results in the activation of both RNAi and JAK/STAT antiviral pathways. ZIKV-infected Aedes aegypti were fed blood containing demethylasterriquinone B1 (DMAQ-B1), a potent insulin mimetic, in combination with AKT inhibitor VIII. Activation of this coordinated response additively reduced ZIKV levels in Aedes aegypti. This effect included a quantitatively greater reduction in salivary gland ZIKV levels up to 11 d post-bloodmeal ingestion, relative to single pathway activation. Together, our study indicates the potential for field delivery of these small molecules to substantially reduce virus transmission from mosquito to human. As infections like Zika virus are becoming more burdensome and prevalent, understanding how to control this family of viruses in the insect vector is an important issue in public health.

DOI: https://doi.org/10.1371/journal.ppat.1010411
Zootaxa. 2022 Feb 03. 5094(2): 261-287

Rediscovering the mosquito fauna (Diptera: Culicidae) of Estonia: an annotated checklist with distribution maps and DNA evidence.

Heli Kirik, Lea Tummeleht, Olavi Kurina.

Female mosquitoes (Diptera: Culicidae) affect their hosts in numerous negative ways and are crucial to the spread of vector-borne pathogens. It is, therefore, important to have a detailed overview of regional mosquitoes, to be able to detect changes in species diversity and identify possible health threats. The aim of this study was to update the checklist of the mosquito fauna of Estonia for the first time since 1957. For this purpose, 24,344 adult mosquitoes (94% females) were collected in Estonia from 2008 to 2020 using various trapping methods. Specimens were primarily identified by morphological characteristics, but DNA barcoding based on the partial cytochrome c oxidase subunit 1 gene (COI) was also used. Species were included in the checklist based on historical records as well as new collections, while also considering reports from neighboring countries. Species records are supplemented with voucher specimens, distribution maps and DNA evidence. The updated checklist includes 34 species, 27 of which were confirmed with recently collected material. All in all, Aedes communis (de Geer, 1776) proved to be the most common mosquito in Estonia, accounting for 30.1% of the specimens collected. This is noteworthy, as this species has been implicated in the transmission of multiple disease agents present in the area. New evidence revealed the presence of Ae. hexodontus Dyar, 1916, Ae. sticticus (Meigen, 1838), Anopheles messeae Falleroni, 1926 and Culiseta bergrothi (Edwards, 1921) in Estonia.

DOI: https://doi.org/10.11646/zootaxa.5094.2.3
J Med Entomol. 2022 Apr 07. pii: tjac032. [Epub ahead of print]

Fitness Cost of Sequential Selection with Deltamethrin in Aedes aegypti (Diptera: Culicidae).

Francisco J Gonzalez-Santillan, Yamili Contreras-Perera, Jesus A Davila-Barboza, Alan E Juache-Villagrana, Selene M Gutierrez-Rodriguez, Gustavo Ponce-Garcia, Beatriz Lopez-Monroy, Iram P Rodriguez-Sanchez, Audrey E Lenhart, Lucy Mackenzie-Impoinvil, Adriana E Flores.

  In Mexico, Aedes aegypti (L.) is the primary dengue vector, chikungunya, and Zika viruses. The continued use of synthetic pyrethroids has led to the development of resistance in target populations, which has diminished the effectiveness of vector control programs. Resistance has been associated with disadvantages that affect the biological parameters of resistant mosquitoes compared to susceptible ones. In the present study, the disadvantages were evaluated by parameters related to survival and reproduction ('fitness cost') after selection with deltamethrin for five generations. The parameters analyzed were the length of the development cycle, sex ratio, survival, longevity, fecundity, egg viability, preoviposition, oviposition and postoviposition periods, and growth parameters. In the deltamethrin-selected strain, there was a decrease in the development cycle duration, the percentage of pupae, the oviposition period, and eggs viability. Although mean daily fecundity was not affected after the selection process, this, together with the decrease in the survival and fecundity levels by specific age, significantly affected the gross reproductive rate (GRR), net reproductive rate (Ro), and intrinsic growth rate (rm) of the group selected for five generations with deltamethrin compared to the group without selection. Identifying the 'cost' of resistance in biological fitness represents an advantage if it is desired to limit the spread of resistant populations since the fitness cost is the less likely that resistant individuals will spread in the population. This represents an important factor to consider in designing integrated vector management programs.

Keywords:  deltamethrin; fitness cost; sequential selection

DOI:  https://doi.org/10.1093/jme/tjac032
J Med Entomol. 2022 Apr 07. pii: tjac039. [Epub ahead of print]

First Detection of the Invasive Mosquito Vector Aedes albopictus (Diptera: Culicidae) in Benin, West Africa, 2021.

Anges Yadouleton, Gildas Hounkanrin, Carine Tchibozo, Alexandra Bialonski, Jonas Schmidt-Chanasit, Hanna Jöst.

  Aedes albopictus (Skuse) is native to Southeast Asia and has colonized tropical and temperate regions worldwide in the last three to four decades. In Africa, data on its distribution is incomplete. Most studies having focused on the abundance, competition to other species, and phylogenetics of this vector are from the central African region. Here, we report the first detection of Ae. albopictus in Benin, West Africa. A total of 13 specimens were collected during the study period in 2021. The phylogenetic analysis of a cytochrome oxidase c subunit I gene fragment revealed a close relationship to populations from tropical India. Because of its close geographical proximity to areas where it has been found, it is assumed that the species was introduced several years before and is currently widely distributed in Benin. Additional studies are needed to explore its distribution, expansion range, and competitive effects on native species.

Keywords:   Aedes albopictus ; Africa; Benin

DOI:  https://doi.org/10.1093/jme/tjac039
Ethiop J Health Sci. 2021 Nov;31(6): 1215-1222

Five-Year Trend Analysis of Malaria Cases in East Shawa Zone, Ethiopia.

Temesgen File, Bayissa Chala.

  Background: Malaria is an infectious disease caused by Plasmodium parasites. Of the five human malaria parasites Plasmodium falciparum and Plasmodium vivax are the two co-endemic predominant and widely distributed species in Ethiopia, with major public health importance. Even though enormous effort has been made countrywide to reduce the disease burden little was reported about trends of malaria transmission in the several localities of malarious areas like East Shawa Zone, Ethiopia. Thus, the present study was aimed at assessing fiveyear (2016-2020) trends of malaria transmission at Adama, Boset and Lume districts of East Shawa Zone of Oromia Regional State, Ethiopia.Methods: Retrospective data was extracted from the central surveillance database of East Shawa Zone Health Office. The data collected was analyzed from September 2020 to December 2020 to examine trends of malaria epidemiology in three malarious districts in the Zone.
Results: The results of the present study showed a remarkable decrease in slide positivity rate (SPR) from 16.3 to 1.4% from 2016 to 2018 in the areas. However, a recent slight increase of malaria SPR was observed. On the other hand, as age increases more male individuals were infected with malaria compared to female of similar age groups. Falciparum, vivax and mixed malaria infection accounted for 53%, 41% and 6% respectively.
Conclusions: Even though, an overall reduction of malaria incidence was revealed in the study areas, an increase in malaria SPR was observed in 2019 and 2020. Such inconsistency in reduction of malaria cases in the study area demands due attention of health planners.

Keywords:  Malaria; Plasmodium falciparum; Plasmodium vivax; prevalence; slide positivity rate

DOI:  https://doi.org/10.4314/ejhs.v31i6.17
Front Med (Lausanne). 2022 ;9 797674

Dengue and Dengue Virus in Guangdong, China, 1978-2017: Epidemiology, Seroprevalence, Evolution, and Policies.

Fengfu Cui, Feiwu He, Xiaorong Huang, Lina Tian, Saiqiang Li, Chumin Liang, Lilian Zeng, Huifang Lin, Juan Su, Liping Liu, Wei Zhao, Limei Sun, Lifeng Lin, Jiufeng Sun.

  Background: Guangdong is a hyperepidemic area of dengue, which has over 0.72 million cumulative cases within the last four decades, accounting for more than 90% of cases in China. The local epidemic of dengue in Guangdong is suspected to be triggered by imported cases and results in consequent seasonal transmission. However, the comprehensive epidemiological characteristics of dengue in Guangdong are still unclear.Methods: The epidemiology, seroprevalence, molecular evolution of dengue virus, and the development of policies and strategies on the prevention and control of dengue were analyzed in Guangdong, China from 1978 to 2017.
Findings: Seasonal transmission of dengue virus in Guangdong, China was mainly sustained from July to October of each year. August to September was the highest risk period of local dengue outbreaks. Most of the dengue cases in Guangdong were young and middle-aged adults. Five hundred and three fatal cases were recorded, which declined within the last two decades (n = 10). The serological test of healthy donors' serum samples showed a positive rate of 5.77%. Dengue virus 1-4 (DENV 1-4) was detected in Guangdong from 1978 to 2017. DENV 1 was the dominant serotype of dengue outbreaks from 1978 to 2017, with an increasing tendency of DENV 2 since 2010. Local outbreaks of DENV 3 were rare. DENV 4 was only encountered in imported cases in Guangdong, China. The imported cases were the main source of outbreaks of DENV 1-2. Early detection, management of dengue cases, and precise vector control were the key strategies for local dengue prevention and control in Guangdong, China.
Interpretation: Dengue has not become an endemic arboviral disease in Guangdong, China. Early detection, case management, and implementation of precise control strategies are key findings for preventing local dengue transmission, which may serve for countries still struggling to combat imported dengue in the west pacific areas.

Keywords:  dengue; dengue virus; molecular epidemiology; policies; seroprevalence

DOI:  https://doi.org/10.3389/fmed.2022.797674
PLoS One. 2022 ;17(4): e0266840

West Nile and Usutu virus seroprevalence in Hungary: A nationwide serosurvey among blood donors in 2019.

Anna Nagy, Nikolett Csonka, Mária Takács, Eszter Mezei, Éva Barabás.

In Hungary, West Nile virus (WNV) has been responsible for 459 laboratory confirmed human cases between 2004 and 2019, while the first human Usutu virus (USUV) infection was confirmed only in 2018. A comprehensive serosurvey was conducted among blood donors to assess the WNV and USUV seroprevalence in 2019, one year after the largest European WNV epidemic. Altogether, 3005 plasma samples were collected and screened for WNV and USUV specific Immunoglobulin G (IgG) antibodies by Enzyme-Linked Immunosorbent Assay (ELISA). All reactive samples were further tested for tick-borne encephalitis virus IgG antibodies by ELISA. Indirect immunofluorescence test and microneutralization assay were used as confirmatory methods. Overall, the WNV seroprevalence was 4.32%, and in five blood donors USUV seropositivity was confirmed. The highest seroprevalence was measured in Central, Eastern and Southern Hungary, while the Western part of the country proved to be less affected. There was a statistically strong association between the WNV seroprevalence of 2019 and the cumulative incidence in the period of 2004 and 2019 calculated for every NUTS 3 region. The last WNV serological screening was performed in 2016 and the prevalence of anti-WNV IgG proved to be 2.19%. One year after the 2018 WNV outbreak, a significant increase in seroprevalence was observed in the Hungarian population and evidence for USUV seropositivity was also obtained. The spatial pattern of seroprevalence can support the identification of high-risk areas raising awareness of the need for increased surveillance, such as screening vector, equine, and avian populations. The communication with general practitioners and other professionals in primary health care services can support the early identification of acute human cases. Education and awareness-raising on the importance of protection against mosquito vectors amongst residents are also important parts of preventive measures.

DOI: https://doi.org/10.1371/journal.pone.0266840
Infect Dis Poverty. 2022 Apr 05. 11(1): 39

Reaching the malaria elimination goal in Brazil: a spatial analysis and time-series study.

Gabriel Zorello Laporta, Maria Eugenia Grillet, Sheila Rodrigues Rodovalho, Eduardo Massad, Maria Anice Mureb Sallum.

  BACKGROUND: Since 2015, the Global Technical Strategy (GTS) for Malaria 2016-2030 has been adopted by the World Health Organization (WHO) as a comprehensive framework to accelerate progress for malaria elimination in endemic countries. This strategy sets the target of reducing global malaria incidence and mortality rates by 90% in 2030. Here it is sought to evaluate Brazil's achievements towards reaching the WHO GTS milestone in 2030. Considering the total number of new malaria cases in 2015, the main research question is: will Brazil reach the malaria elimination goal in 2030?METHODS: Analytical strategies were undertaken using the SIVEP-malaria official databases of the Brazilian Malaria Control Programme for the Brazilian Amazon region from 2009 to 2020. Spatial and time-series analyses were applied for identifying municipalities that support the highest numbers of malaria cases over the years. Forecast analysis was used for predicting the estimated number of new cases in Brazil in 2025-2050.
RESULTS: Brazil has significantly reduced the number of new malaria cases in 2020 in comparison with 2015 in the states of Acre (- 56%), Amapá (- 75%), and Amazonas (- 21%); however, they increased in the states of Pará (156%), Rondônia (74%), and Roraima (362%). Forecast of the predicted number of new malaria cases in 2030 is 74,764 (95% CI: 41,116-141,160) in the Brazilian Amazon.
CONCLUSIONS: It is likely that Brazil will reduce the number of new malaria cases in the Brazilian Amazon in 2030 in relation to that in 2015. Herein forecast shows a reduction by 46% (74,754 in 2030 forecast/137,982 in 2015), but this reduction is yet far from the proposed reduction under the WHO GTS 2030 milestone (90%). Stable and unbeatable transmission in the Juruá River Valley, Manaus, and Lábrea still support endemic malaria in the Brazilian Amazon. Today's cross-border malaria is impacting the state of Roraima unprecedently. If this situation is maintained, the malaria elimination goal (zero cases) may not be reached before 2050. An enhanced political commitment is vital to ensure optimal public health intervention designs in the post-2030 milestones for malaria elimination.

Keywords:  Antimalarials therapeutic use; Brazil; Eradication; Malaria; Policy; Prevention and control

DOI:  https://doi.org/10.1186/s40249-022-00945-5
Rev Inst Med Trop Sao Paulo. 2022 ;pii: S0036-46652022000100214. [Epub ahead of print]64 e29

Malaria at international borders: challenges for elimination on the remote Brazil-Peru border.

Monica Palma-Cuero, Myrna Barata Machado, Jucelia Taiz Bruno Graça, Ney Batista Dos Anjos, Rafael Santos Pereira, Martha Cecilia Suárez-Mutis.

Understanding local epidemiology is essential to reduce the burden of malaria in complex contexts, such as Brazilian municipalities that share borders with endemic countries. A descriptive study of malaria in the period 2003 to 2020 was conducted using data from the Malaria Epidemiological Surveillance Information System related to a remote municipality with an extensive border with Peru to understand the disease transmission, focusing on the obstacles to its elimination. The transmission increases at the end of the rainy season. During the period of 18 years, 53,575 malaria cases were reported (Mean of API 224.7 cases/1,000), of which 11% were imported from Peru. Thirteen outbreaks of malaria were observed during the studied period, the last one in 2018. The highest burden of cases was caused by P. vivax (73.2%), but P. falciparum was also prevalent at the beginning of the study period (50% in 2006). Several changes in the epidemiological risk were observed: (1) the proportion of international imported cases of malaria changed from 30.7% in 2003 to 3.5% in 2020 (p<0.05); (2) indigenous people affected increased from 24.3% in 2003 to 89.5% in 2020 (p<0.0001); (3) infected children and adolescents < 15 years old increased from 50.2% in 2003 to 67.4% in 2020 (p<0.01); (4) the proportion of men decreased from 56.7% in 2003 to 50.4% in 2020 (p<0.01); (5) the likelihood of P. falciparum malaria has significantly declined (p<0.01). The number of cases and the incidence of malaria in 2019 and 2020 were the lowest in the period of 18 years. The burden of malaria in indigenous areas and its determinants, seasonality, geographical access and the long international border are obstacles for the elimination of malaria that must be overcome.

DOI: https://doi.org/10.1590/S1678-9946202264029
J Trop Med. 2022 ;2022 1784012

Prevalence and Associated Factors of Malaria Infection among Outpatients Visiting Shewa Robit Health Center, Northcentral Ethiopia.

Azene Tesfaye, Tadegew Teshome.

Introduction: Malaria infection is a serious health problem killing millions in tropical developing countries including Ethiopia. The present study focused on assessing malaria prevalence and identification of determinants in Shewa Robit, northcentral Ethiopia.Methods: A cross-sectional study was conducted among 422 participants who visited Shewa Robit Health Center between 01/10/2017 and 30/04/2018, using a simple random sampling. Sociodemographic characteristics were recorded using a pre-tested semi-structured questionnaire and infection was confirmed by microscopic examination. Data were analyzed using the Statistical Program for Social Sciences (SPSS) version 20 and p < 0.05 was used to indicate the level of significance.
Results: Eighty-one (19.0%) microscopically confirmed malaria cases were recorded, P.vivax was the most frequently detected species (n = 58; 71.6%). Interestingly, 73.2% (n = 309) of the participant did not utilize LLINs due to the fear of toxicity (37.4%, n = 158), misconception (21.6%, n = 91), and shortage (14.2%, n = 60). The data showed age, gender, marital status, family size, usage of LLINs and application of IRS, proximity to mosquito breeding sites and less robust and porous walls were the determinants of the infection in the study area.
Conclusion: The prevalence of malaria in the study population was high and P. vivax being the most common causative agent. Environmental and behavioral factors related to LLIN are the potential determinants of malaria. Continued public health interventions, targeting proper utilization of bed nets, drainage of stagnant water, and improved public awareness about reducing the risk of insect bites have the potential to minimize the infection.

DOI: https://doi.org/10.1155/2022/1784012