bims-mosdis 2022-02-27 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2022–02–27
29 papers selected by
Richard Halfpenny, Staffordshire University

Dataset for aedes aegypti (diptera: Culicidae) and culex quinquefasciatus (diptera: Culicidae) collections from key West, Florida, USA, 2010-2020.
Spatiotemporal distribution and insecticide resistance status of Aedes aegypti in Ghana.
Large-scale (Phase III) evaluation of broflanilide 50WP (VECTRON™ T500) for indoor residual spraying for malaria vector control in Northeast Tanzania: study protocol for a two-arm, non-inferiority, cluster-randomised community trial.
Imported Dengue Case Numbers and Local Climatic Patterns Are Associated with Dengue Virus Transmission in Florida, USA.
Reduced dengue incidence during the COVID-19 movement restrictions in Sri Lanka from March 2020 to April 2021.
Introgression of the Aedes aegypti Red-Eye Genetic Sexing Strains Into Different Genomic Backgrounds for Sterile Insect Technique Applications.
Patterns of Kdr-L995F Allele Emergence Alongside Detoxifying Enzymes Associated with Deltamethrin Resistance in Anopheles gambiae s.l. from North Cameroon.
A decade of stability for wMel Wolbachia in natural Aedes aegypti populations.
Wolbachia in Aedes koreicus: Rare Detections and Possible Implications.
Increased biting rate and decreased Wolbachia density in irradiated Aedes mosquitoes.
Detection of Rift Valley Fever Virus in Aedes (Aedimorphus) durbanensis, South Africa.
Temporal Evaluation of Insecticide Resistance in Populations of the Major Arboviral Vector Aedes Aegypti from Northern Nigeria.
Recombinant Mosquito Densovirus with Bti Toxins Significantly Improves Pathogenicity against Aedes albopictus.
Could Sterile Aedes albopictus Male Releases Interfere with Aedes aegypti Population in Reunion Island?
Regulation of genetically engineered (GE) mosquitoes as a public health tool: a public health ethics analysis.
Adaptive Evolution as a Driving Force of the Emergence and Re-Emergence of Mosquito-Borne Viral Diseases.
Multiplex PCR Assay for the Identification of Four Species of the Anopheles Leucosphyrus Sub-Group in Malaysia.
Uncovering the Burden of Dengue in Africa: Considerations on Magnitude, Misdiagnosis, and Ancestry.
Seasonality and Biting Behavior of Mansonia (Diptera, Culicidae) in Rural Settlements Near Porto Velho, State of Rondônia, Brazil.
Joint spatiotemporal modelling reveals seasonally dynamic patterns of Japanese encephalitis vector abundance across India.
Permethrin-treated baby wraps for the prevention of malaria: results of a randomized controlled pilot study in rural Uganda.
Plasmodium falciparum parasite prevalence in East Africa: Updating data for malaria stratification.
Hyperendemic Dengue and Possible Zika Circulation in the Westernmost Region of the Indonesian Archipelago.
Spatial distribution of malaria and primary healthcare in Cametá and Tucuruí, Pará state, Brazil.
Spread of a Novel Indian Ocean Lineage Carrying E1-K211E/E2-V264A of Chikungunya Virus East/Central/South African Genotype across the Indian Subcontinent, Southeast Asia, and Eastern Africa.
Identification of a biological form in the Anopheles stephensi laboratory colony using the odorant-binding protein 1 intron I sequence.
Trends in malaria epidemiological factors following the implementation of current control strategies in Dangassa, Mali.
West Nile and Usutu Virus Introduction via Migratory Birds: A Retrospective Analysis in Italy.
Fine-scale heterogeneity in population density predicts wave dynamics in dengue epidemics.

Data Brief. 2022 Apr;41 107907

Dataset for aedes aegypti (diptera: Culicidae) and culex quinquefasciatus (diptera: Culicidae) collections from key West, Florida, USA, 2010-2020.

Catherine A Pruszynski.

  The Florida Keys Mosquito Control District began deploying Biogents® BG Sentinel traps to monitor Aedes aegypti (Diptera: Culicidae) populations in Key West during a small autochthonous dengue outbreak that began in November 2009. This paper provides weekly data for twelve collection points from January 2010 through December 2020. BG Sentinel traps were baited with dry ice and proprietary BG Lure and were set in the afternoon and retrieved the following morning totalling 19 collection hours. Trap collections also included Culex quinquefasciatus and thus data for that species is also included. The collection data could provide insight into dengue transmission in a small sub-tropical US city.

Keywords:  Dengue; Mosquito; Surveillance; Trapping; Vector

DOI:  https://doi.org/10.1016/j.dib.2022.107907
Parasit Vectors. 2022 Feb 19. 15(1): 61

Spatiotemporal distribution and insecticide resistance status of Aedes aegypti in Ghana.

Christopher M Owusu-Asenso, Julius A A Mingle, David Weetman, Yaw A Afrane.

   BACKGROUND: Vector control is the main intervention used to control arboviral diseases transmitted by Aedes mosquitoes because there are no effective vaccines or treatments for most of them. Control of Aedes mosquitoes relies heavily on the use of insecticides, the effectiveness of which may be impacted by resistance. In addition, rational insecticide application requires detailed knowledge of vector distribution, dynamics, resting, and feeding behaviours, which are poorly understood for Aedes mosquitoes in Africa. This study investigated the spatiotemporal distribution and insecticide resistance status of Aedes aegypti across ecological extremes of Ghana.
METHODS: Immature mosquitoes were sampled from containers in and around human dwellings at seven study sites in urban, suburban, and rural areas of Ghana. Adult Aedes mosquitoes were sampled indoors and outdoors using Biogents BG-Sentinel 2 mosquito traps, human landing catches, and Prokopack aspiration. Distributions of immature and adult Aedes mosquitoes were determined indoors and outdoors during dry and rainy seasons at all sites. The phenotypic resistance status of Aedes mosquitoes to insecticides was determined using World Health Organization susceptibility bioassays. The host blood meal source was determined by polymerase chain reaction.
RESULTS: A total of 16,711 immature Aedes were sampled, with over 70% found in car tyres. Significantly more breeding containers had Aedes immatures during the rainy season (11,856; 70.95%) compared to the dry season (4855; 29.05%). A total of 1895 adult Aedes mosquitos were collected, including Aedes aegypti (97.8%), Aedes africanus (2.1%) and Aedes luteocephalus (0.1%). Indoor sampling of adult Aedes yielded a total of 381 (20.1%) and outdoor sampling a total of 1514 (79.9%) mosquitoes (z = - 5.427, P = 0.0000) over the entire sampling period. Aedes aegypti populations were resistant to dichlorodiphenyltrichloroethane at all study sites. Vectors showed suspected resistance to bendiocarb (96-97%), permethrin (90-96%) and deltamethrin (91-96%), and were susceptible to the organophosphate for all study sites. Blood meal analysis showed that the Aedes mosquitoes were mostly anthropophilic, with a human blood index of 0.9 (i.e. humans, 90%; human and dog, 5%; dog and cow, 5%).
CONCLUSIONS: Aedes mosquitoes were found at high densities in all ecological zones of Ghana. Resistance of Aedes spp. to pyrethroids and carbamates may limit the efficacy of vector control programmes and thus requires careful monitoring.

Keywords:  Aedes aegypti; Ghana; Human blood index; Insecticide resistance; Seasons

DOI:  https://doi.org/10.1186/s13071-022-05179-w
BMC Infect Dis. 2022 Feb 21. 22(1): 171

Large-scale (Phase III) evaluation of broflanilide 50WP (VECTRON™ T500) for indoor residual spraying for malaria vector control in Northeast Tanzania: study protocol for a two-arm, non-inferiority, cluster-randomised community trial.

Patrick K Tungu, Mark W Rowland, Louisa A Messenger, Graham J Small, John Bradley, Janneke Snetselaar, Matthew J Kirby, Njelembo J Mbewe.

   BACKGROUND: Indoor residual spraying (IRS) is a major method of malaria vector control across sub-Saharan Africa. Effective control is being undermined by the rapid spread of insecticide resistance. There is major investment in development of new insecticides for IRS that possess novel modes of action, long residual activity, low mammalian toxicity and minimal cross-resistance. VECTRON™ T500, a new IRS product containing the active ingredient broflanilide as a 50% wettable powder (WP), has been shown to be efficacious against pyrethroid susceptible and resistant vector species on mud and concrete substrates in experimental hut (Phase II) trials.
METHODS: A two-arm non-inferiority cluster randomized controlled trial (Phase III) will be undertaken in Muheza District, Tanga Region, Tanzania. VECTRON™ T500 will be compared to the IRS product Fludora® Fusion (clothianidin 50% WP + deltamethrin 6.25% WP). The predominant malaria vectors in the study area are pyrethroid-resistant Anopheles gambiae s.s., An. arabiensis and An. funestus s.s. Sixteen village clusters will be pair-matched on baseline vector densities and allocated to reference and intervention arms. Consenting households in the intervention arm will be sprayed with VECTRON™ T500 and those in the reference arm will be sprayed with Fludora® Fusion. Each month, CDC light traps will collect mosquitoes to estimate changes in vector density, indoor biting, sporozoite and entomological inoculation rates (EIR). Susceptibility to IRS active ingredients will be assessed using World Health Organisation (WHO) bottle bioassays. Target site and metabolic resistance mechanisms will be characterised among Anopheles field populations from both trial arms. Residual efficacy of both IRS products will be monitored for 12 months post intervention. Questionnaire and focus group discussions will explore factors that influence adherence, adverse effects and benefits of IRS.
DISCUSSION: This protocol describes a large-scale non-inferiority evaluation of a novel IRS product to reduce the density and EIR of pyrethroid-resistant Anopheles vectors. If VECTRON™ T500 proves non-inferior to Fludora® Fusion, it will be considered as an additional vector control product for malaria prevention and insecticide resistance management.
TRIAL REGISTRATION: ClinicalTrials.gov, NCT05150808, registered on 26 November 2021. Retrospectively registered.

Keywords:  Broflanilide; Clothianidin; Entomological inoculation rate; Indoor residual spraying; Insecticide resistance; Vector density

DOI:  https://doi.org/10.1186/s12879-022-07138-3
Insects. 2022 Feb 03. pii: 163. [Epub ahead of print]13(2):

Imported Dengue Case Numbers and Local Climatic Patterns Are Associated with Dengue Virus Transmission in Florida, USA.

Caroline Stephenson, Eric Coker, Samantha Wisely, Song Liang, Rhoel R Dinglasan, John A Lednicky.

  Aedes aegypti mosquitoes are the main vector of dengue viruses globally and are present throughout much of the state of Florida (FL) in the United States of America. However, local transmission of dengue viruses in FL has mainly occurred in the southernmost counties; specifically Monroe and Miami-Dade counties. To get a better understanding of the ecologic risk factors for dengue fever incidence throughout FL, we collected and analyzed numerous environmental factors that have previously been connected to local dengue cases in disease-endemic regions. We analyzed these factors for each county-year in FL, between 2009-2019, using negative binomial regression. Monthly minimum temperature of 17.5-20.8 °C, an average temperature of 26.1-26.7 °C, a maximum temperature of 33.6-34.7 °C, rainfall between 11.4-12.7 cm, and increasing numbers of imported dengue cases were associated with the highest risk of dengue incidence per county-year. To our knowledge, we have developed the first predictive model for dengue fever incidence in FL counties and our findings provide critical information about weather conditions that could increase the risk for dengue outbreaks as well as the important contribution of imported dengue cases to local establishment of the virus in Ae. aegypti populations.

Keywords:  Aedes aegypti; dengue virus; imported; risk; transmission; weather

DOI:  https://doi.org/10.3390/insects13020163
BMC Public Health. 2022 Feb 24. 22(1): 388

Reduced dengue incidence during the COVID-19 movement restrictions in Sri Lanka from March 2020 to April 2021.

S N Surendran, R Nagulan, K Sivabalakrishnan, S Arthiyan, A Tharsan, T T P Jayadas, S Raveendran, T Kumanan, R Ramasamy.

   BACKGROUND: Dengue is the major mosquito-borne disease in Sri Lanka. After its first detection in January 2020, COVID-19 has become the major health issue in Sri Lanka. The impact of public health measures, notably restrictions on movement of people to curb COVID-19 transmission, on the incidence of dengue during the period March 2020 to April 2021 was investigated.
METHODS: The incidence of dengue and COVID-19, rainfall and the public movement restrictions implemented to contain COVID-19 transmission were obtained from Sri Lanka government sources. A Seasonal Autoregressive Integrated Moving Average (SARIMA) model was used to predict the monthly dengue incidence from March 2020 to April 2021 for each of the country's 25 districts based on five years of pre-pandemic data, and compared with the actual recorded incidence of dengue during this period. Ovitrap collections of Aedes larvae were performed in Jaffna city in the Jaffna district from August 2020 to April 2021 and the findings compared with similar collections made in the pre-pandemic period from March 2019 to December 2019.
RESULTS: The recorded numbers of dengue cases for every month from March 2020 to April 2021 in the whole country and for all 25 districts over the same period were lower than the numbers of dengue cases predicted from data for the five years (2015-2019) immediately preceding the COVID-19 pandemic. The number of dengue cases recorded nationwide represented a 74% reduction from the predicted number of dengue cases for the March 2020 to April 2021 period. The numbers of Aedes larvae collected from ovitraps per month were reduced by 88.6% with a lower proportion of Ae. aegypti than Ae. albopictus in Jaffna city from August 2020 until April 2021 compared with March 2019 to December 2019.
CONCLUSION: Public health measures that restricted movement of people, closed schools, universities and offices to contain COVID-19 transmission unexpectedly led to a significant reduction in the reported numbers of dengue cases in Sri Lanka. This contrasts with findings reported from Singapore. The differences between the two tropical islands have significant implications for the epidemiology of dengue. Reduced access to blood meals and lower vector densities, particularly of Ae. aegypti, resulting from the restrictions on movement of people, are suggested to have contributed to the lower dengue incidence in Sri Lanka.

Keywords:  Aedes aegypti; Aedes albopictus; COVID-19 containment measures and dengue incidence; Dengue transmission; Dengue vectors; Jaffna district; Sri Lanka

DOI:  https://doi.org/10.1186/s12889-022-12726-8
Front Bioeng Biotechnol. 2022 ;10 821428

Introgression of the Aedes aegypti Red-Eye Genetic Sexing Strains Into Different Genomic Backgrounds for Sterile Insect Technique Applications.

Antonios A Augustinos, Katerina Nikolouli, Lucia Duran de la Fuente, Muhammad Misbah-Ul-Haq, Danilo O Carvalho, Kostas Bourtzis.

  Aedes aegypti is an invasive mosquito species and major vector of human arboviruses. A wide variety of control methods have been employed to combat mosquito populations. One of them is the sterile insect technique (SIT) that has recently attracted considerable research efforts due to its proven record of success and the absence of harmful environmental footprints. The efficiency and cost-effectiveness of SIT is significantly enhanced by male-only releases. For mosquito SIT, male-only releases are ideally needed since females bite, blood-feed and transmit the pathogens. Ae. aegypti genetic sexing strains (GSS) have recently become available and are based on eye colour mutations that were chosen as selectable markers. These genetic sexing strains were developed through classical genetics and it was shown to be subjected to genetic recombination, a phenomenon that is not suppressed in males as is the case in many Diptera. The genetic stability of these GSS was strengthened by the induction and isolation of radiation-induced inversions. In this study, we used the red eye mutation and the inversion Inv35 line of the Ae. aegypti red-eye GSS s and introgressed them in six different genomic backgrounds to develop GSS with the respective local genomic backgrounds. Our goal was to assess whether the recombination frequencies in the strains with and without the inversion are affected by the different genomic backgrounds. In all cases the recombination events were suppressed in all Inv35 GSS strains, thus indicating that the genomic background does not negatively affect the inversion result. Absence of any effect that could be ascribed to genetic differences, enables the introgression of the key elements of the GSS into the local genomic background prior to release to the target areas. Maintaining the local background increases the chances for successful matings between released males and wild females and addresses potential regulatory concerns regarding biosafety and biosecurity.

Keywords:  area wide integrated pest management; insect pest control; mosquitoes; vector control; yellow fever mosquito

DOI:  https://doi.org/10.3389/fbioe.2022.821428
Pathogens. 2022 Feb 15. pii: 253. [Epub ahead of print]11(2):

Patterns of Kdr-L995F Allele Emergence Alongside Detoxifying Enzymes Associated with Deltamethrin Resistance in Anopheles gambiae s.l. from North Cameroon.

Josiane Etang, Stanislas Elysée Mandeng, Philippe Nwane, Herman Parfait Awono-Ambene, Jude D Bigoga, Wolfgang Eyisap Ekoko, Achille Jerome Binyang, Michael Piameu, Lili Ranaise Mbakop, Narcisse Mvondo, Raymond Tabue, Rémy Mimpfoundi, Jean Claude Toto, Immo Kleinschmidt, Tessa Bellamy Knox, Abraham Peter Mnzava, Martin James Donnelly, Etienne Fondjo.

  Understanding how multiple insecticide resistance mechanisms occur in malaria vectors is essential for efficient vector control. This study aimed at assessing the evolution of metabolic mechanisms and Kdr L995F/S resistance alleles in Anopheles gambiae s.l. from North Cameroon, following long-lasting insecticidal nets (LLINs) distribution in 2011. Female An. gambiae s.l. emerging from larvae collected in Ouro-Housso/Kanadi, Be-Centre, and Bala in 2011 and 2015, were tested for susceptibility to deltamethrin + piperonyl butoxide (PBO) or SSS-tributyl-phosphoro-thrithioate (DEF) synergists, using the World Health Organization's standard protocol. The Kdr L995F/S alleles were genotyped using Hot Ligation Oligonucleotide Assay. Tested mosquitoes identified using PCR-RFLP were composed of An. arabiensis (68.5%), An. coluzzii (25.5%) and An. gambiae (6%) species. From 2011 to 2015, metabolic resistance increased in Ouro-Housso/Kanadi (up to 89.5% mortality to deltametnrin+synergists in 2015 versus <65% in 2011; p < 0.02), while it decreased in Be-Centre and Bala (>95% mortality in 2011 versus 42-94% in 2015; p < 0.001). Conversely, the Kdr L995F allelic frequencies slightly decreased in Ouro-Housso/Kanadi (from 50% to 46%, p > 0.9), while significantly increasing in Be-Centre and Bala (from 0-13% to 18-36%, p < 0.02). These data revealed two evolutionary trends of deltamethrin resistance mechanisms; non-pyrethroid vector control tools should supplement LLINs in North Cameroon.

Keywords:  Anopheles gambiae s.l.; Kdr 995F/S alleles; deltamethrin; insecticide resistance; malaria vector control; northern Cameroon; resistance management; synergists

DOI:  https://doi.org/10.3390/pathogens11020253
PLoS Pathog. 2022 Feb 23. 18(2): e1010256

A decade of stability for wMel Wolbachia in natural Aedes aegypti populations.

Perran A Ross, Katie L Robinson, Qiong Yang, Ashley G Callahan, Thomas L Schmidt, Jason K Axford, Marianne P Coquilleau, Kyran M Staunton, Michael Townsend, Scott A Ritchie, Meng-Jia Lau, Xinyue Gu, Ary A Hoffmann.

Mosquitoes carrying Wolbachia endosymbionts are being released in many countries for arbovirus control. The wMel strain of Wolbachia blocks Aedes-borne virus transmission and can spread throughout mosquito populations by inducing cytoplasmic incompatibility. Aedes aegypti mosquitoes carrying wMel were first released into the field in Cairns, Australia, over a decade ago, and with wider releases have resulted in the near elimination of local dengue transmission. The long-term stability of Wolbachia effects is critical for ongoing disease suppression, requiring tracking of phenotypic and genomic changes in Wolbachia infections following releases. We used a combination of field surveys, phenotypic assessments, and Wolbachia genome sequencing to show that wMel has remained stable in its effects for up to a decade in Australian Ae. aegypti populations. Phenotypic comparisons of wMel-infected and uninfected mosquitoes from near-field and long-term laboratory populations suggest limited changes in the effects of wMel on mosquito fitness. Treating mosquitoes with antibiotics used to cure the wMel infection had limited effects on fitness in the next generation, supporting the use of tetracycline for generating uninfected mosquitoes without off-target effects. wMel has a temporally stable within-host density and continues to induce complete cytoplasmic incompatibility. A comparison of wMel genomes from pre-release (2010) and nine years post-release (2020) populations show few genomic differences and little divergence between release locations, consistent with the lack of phenotypic changes. These results indicate that releases of Wolbachia-infected mosquitoes for population replacement are likely to be effective for many years, but ongoing monitoring remains important to track potential evolutionary changes.

DOI: https://doi.org/10.1371/journal.ppat.1010256
Insects. 2022 Feb 21. pii: 216. [Epub ahead of print]13(2):

Wolbachia in Aedes koreicus: Rare Detections and Possible Implications.

Claudia Damiani, Alessia Cappelli, Francesco Comandatore, Fabrizio Montarsi, Aurelio Serrao, Alice Michelutti, Michela Bertola, Maria Vittoria Mancini, Irene Ricci, Claudio Bandi, Guido Favia.

  The emerging distribution of new alien mosquito species was recently described in Europe. In addition to the invasion of Aedes albopictus, several studies have focused on monitoring and controlling other invasive Aedes species, as Aedes koreicus and Aedes japonicus. Considering the increasing development of insecticide resistance in Aedes mosquitoes, new control strategies, including the use of bacterial host symbionts, are proposed. However, little is known about the bacterial communities associated with these species, thus the identification of possible candidates for Symbiotic Control is currently limited. The characterization of the natural microbiota of field-collected Ae. koreicus mosquitoes from North-East Italy through PCR screening, identified native infections of Wolbachia in this species that is also largely colonized by Asaia bacteria. Since Asaia and Wolbachia are proposed as novel tools for Symbiotic Control, our study supports their use for innovative control strategies against new invasive species. Although the presence of Asaia was previously characterized in Ae. koreicus, our study characterized this Wolbachia strain, also inferring its phylogenetic position. The co-presence of Wolbachia and Asaia may provide additional information about microbial competition in mosquito, and to select suitable phenotypes for the suppression of pathogen transmission and for the manipulation of host reproduction in Ae. koreicus.

Keywords:  Aedes koreicus; Asaia; Wolbachia; microbiota

DOI:  https://doi.org/10.3390/insects13020216
Parasit Vectors. 2022 Feb 24. 15(1): 67

Increased biting rate and decreased Wolbachia density in irradiated Aedes mosquitoes.

Riccardo Moretti, Elena Lampazzi, Claudia Damiani, Giulia Fabbri, Giulia Lombardi, Claudio Pioli, Angiola Desiderio, Aurelio Serrao, Maurizio Calvitti.

   BACKGROUND: Releasing considerable numbers of radiation-sterilized males is a promising strategy to suppress mosquito vectors. However, releases may also include small percentages of biting females, which translate to non-negligible numbers when releases are large. Currently, the effects of irradiation on host-seeking and host-biting behaviors have not been exhaustively investigated. Information is also lacking regarding the effects of sterilizing treatment on the endosymbiotic bacterium Wolbachia, which is known to affect the vector competence of infected mosquitos.
METHODS: To ascertain the effects of irradiation on females, the pupae of two Aedes albopictus strains, differing in their natural or artificial Wolbachia infection type, and Aedes aegypti-which is not infected by Wolbachia-were treated with various doses of X-rays and monitored for key fitness parameters and biting behavior over a period of 2 weeks. The effect of radiation on Wolbachia was investigated by quantitative polymerase chain reaction (qPCR) and fluorescence in situ hybridization (FISH) analysis.
RESULTS: Partial Aedes albopictus female sterility was achieved at 28 Gy, but the number of weekly bites more than doubled compared to that of the controls. Radiation doses of 35 and 45 Gy completely inhibited progeny production but did not significantly affect the survival or flight ability of Ae. albopictus females and caused a tripling of the number of bites per female per week (compared to untreated controls). These results were also confirmed in Ae. aegypti after treatment at 50 Gy. Wolbachia density decreased significantly in 45-Gy-irradiated females, with the greatest decreases in the early irradiation group (26 ± 2-h-old pupae). Wolbachia density also decreased as adults aged. This trend was confirmed in ovaries but not in extra-ovarian tissues. FISH analysis showed a strongly reduced Wolbachia-specific fluorescence in the ovaries of 13 ± 1-day-old females.
CONCLUSIONS: These results suggest that, under sterile insect technique (SIT) programs, the vector capacity of a target population could increase with the frequency of the irradiated females co-released with the sterile males due to an increased biting rate. In the context of successful suppression, the related safety issues are expected to be generally negligible, but they should be conservatively evaluated when large-scale programs relying on imperfect sexing and high overflooding release ratios are run for long periods in areas endemic for arboviral diseases. Also, the effects of irradiation on the vector competence deserve further investigation.

Keywords:  Aedes aegypti; Aedes albopictus; Biting rate; Blood-feeding; FISH analysis; Host-seeking; Radiation biology; SIT; Vectorial capacity; Wolbachia; Wolbachia density; X-ray irradiation; qPCR

DOI:  https://doi.org/10.1186/s13071-022-05188-9
Pathogens. 2022 Jan 21. pii: 125. [Epub ahead of print]11(2):

Detection of Rift Valley Fever Virus in Aedes (Aedimorphus) durbanensis, South Africa.

Carien van den Bergh, Peter N Thompson, Robert Swanepoel, Antonio P G Almeida, Janusz T Paweska, Petrus Jansen van Vuren, William C Wilson, Alan Kemp, Estelle H Venter.

  Rift Valley fever virus (RVFV) is a mosquito-borne, zoonotic phlebovirus-causing disease in domestic ruminants and humans in Africa, the Arabian Peninsula and some Indian Ocean islands. Outbreaks, characterized by abortion storms and a high morbidity rate in newborn animals, occur after heavy and prolonged rainfalls favouring the breeding of mosquitoes. However, the identity of the important mosquito vectors of RVFV is poorly known in most areas. Mosquitoes collected in the Ndumo area of tropical north-eastern KwaZulu-Natal (KZN), South Africa, were tested for RVFV nucleic acid using RT-PCR. The virus was detected in a single pool of unfed Aedes (Aedimorphus) durbanensis, indicating that this seasonally abundant mosquito species could serve as a vector in this area of endemic RVFV circulation. Phylogenetic analysis indicated the identified virus is closely related to two isolates from the earliest outbreaks, which occurred in central South Africa more than 60 years ago, indicating long-term endemicity in the region. Further research is required to understand the eco-epidemiology of RVFV and the vectors responsible for its circulation in the eastern tropical coastal region of southern Africa.

Keywords:  Aedes (Aedimorphus) durbanensis; Rift Valley fever virus; mosquito vector; transmission

DOI:  https://doi.org/10.3390/pathogens11020125
Insects. 2022 Feb 10. pii: 187. [Epub ahead of print]13(2):

Temporal Evaluation of Insecticide Resistance in Populations of the Major Arboviral Vector Aedes Aegypti from Northern Nigeria.

Muhammad M Mukhtar, Sulaiman S Ibrahim.

  To support evidence-based control measures, two Nigerian Aedes populations (BUK and Pantami) were characterised. Larval bioassay using temephos and deltamethrin revealed a significant increase in deltamethrin resistance, with LC50 of 0.018mg/L (resistance ratio compared to New Orleans, RR = 2.250) in 2018 increasing ~6-fold, by 2019 (LC50 = 0.100mg/L, RR = 12.5), and ~11-fold in 2020 (LC50 = 0.198mg/L, RR = 24.750). For the median deltamethrin concentration (0.05mg/L), a gradual decrease in mortality was observed, from 50.6% in 2018, to 44.9% in 2019, and 34.2% in 2020. Extremely high DDT resistance was observed, with <3% mortalities and LT50s of 352.87 min, 369.19 min and 406.94 min in 2018, 2019 and 2020, respectively. Significant temporal increase in resistance was observed towards ƛ-cyhalothrin (a type II pyrethroid) over three years. Synergist bioassays with diethylmaleate and piperonylbutoxide significantly recovered DDT and ƛ-cyhalothrin susceptibility respectively, implicating glutathione S-transferases and CYP450s. Cone bioassays revealed increased resistance to the PermaNet® 3.0, side panels (mortalities of 94% in 2018, 66.4% in 2019, and 73.6% in 2020), while full susceptibility was obtained with the roof of PermaNet® 3.0. The F1534C kdr mutation occurred in low frequency, with significant correlation between heterozygote genotypes and DDT resistance. This temporal increase in resistance is a major challenge for control of this vector of public health importance.

Keywords:  Aedes aegypti; Nigeria; enzymes; increase; insecticides; kdr; metabolic; resistance; temporal

DOI:  https://doi.org/10.3390/insects13020187
Toxins (Basel). 2022 Feb 17. pii: 147. [Epub ahead of print]14(2):

Recombinant Mosquito Densovirus with Bti Toxins Significantly Improves Pathogenicity against Aedes albopictus.

Khadija Batool, Intikhab Alam, Peiwen Liu, Zeng Shu, Siyu Zhao, Wenqiang Yang, Xiao Jie, Jinbao Gu, Xiao-Guang Chen.

  Mosquito densoviruses (MDVs) are mosquito-specific viruses that are recommended as mosquito bio-control agents. The MDV Aedes aegypti densovirus (AeDNV) is a good candidate for controlling mosquitoes. However, the slow activity restricts their widespread use for vector control. In this study, we introduced the Bacillus thuringiensis (Bti) toxin Cry11Aa domain II loop α8 and Cyt1Aa loop β6-αE peptides into the AeDNV genome to improve its mosquitocidal efficiency; protein expression was confirmed using nanoscale liquid chromatography coupled to tandem mass spectrometry (nano LC-MS/MS). Recombinant plasmids were transfected into mosquito C6/36 cell lines, and the expression of specific peptides was detected through RT-PCR. A toxicity bioassay against the first instar Aedes albopictus larvae revealed that the pathogenic activity of recombinant AeDNV was significantly higher and faster than the wild-type (wt) viruses, and mortality increased in a dose-dependent manner. The recombinant viruses were genetically stable and displayed growth phenotype and virus proliferation ability, similar to wild-type AeDNV. Our novel results offer further insights by combining two mosquitocidal pathogens to improve viral toxicity for mosquito control.

Keywords:  Ae. albopictus; Aedes aegypti densovirus; Bacillus thuringiensis; toxicity

DOI:  https://doi.org/10.3390/toxins14020147
Insects. 2022 Jan 29. pii: 146. [Epub ahead of print]13(2):

Could Sterile Aedes albopictus Male Releases Interfere with Aedes aegypti Population in Reunion Island?

Harilanto Felana Andrianjakarivony, David Damiens, Lucie Marquereau, Benjamin Gaudillat, Nausicaa Habchi-Hanriot, Louis-Clément Gouagna.

  In Reunion Island, the feasibility of an Aedes albopictus control program using the Sterile Insect Technique (SIT) is studied. Because, in some regions, Ae. albopictus is living in sympatry with Aedes aegypti, the impact of releasing millions of sterile male Ae. albopictus on female Ae. aegypti reproduction needs to be assessed. Thus, to study the potential heterospecific matings, a marking technique using rhodamine B has been used. Rhodamine is given in solution to male mosquitoes to be incorporated into the male body and seminal fluid and transferred during mating into the bursa inseminalis and spermathecae of females. The presence of rhodamine in females occurred in 15% of cases when Ae. aegypti females were offered non-irradiated Ae. albopictus males, 5% when offered irradiated Ae. albopictus males and 18% of cases in the inverse heterospecific matings. Moreover, our results also showed that these matings gave few eggs but were not viable. Finally, the results showed that whatever the type of mating crosses, females in cages previously crossed with males of another species can re-mate with males of their species and produce an equivalent amount of egg compared to females only mated with conspecific males. Despite the promiscuity of the males and females in small cages for three days, heterospecific mating between sterile male Ae. albopictus and female Ae aegypti, 95% of the females have not been inseminated suggesting that in the field the frequency satyrization would be very low.

Keywords:  heterospecific mating; rhodamine; sterile insect technique

DOI:  https://doi.org/10.3390/insects13020146
Global Health. 2022 Feb 21. 18(1): 21

Regulation of genetically engineered (GE) mosquitoes as a public health tool: a public health ethics analysis.

Zahra Meghani.

   BACKGROUND: In recent years, genetically engineered (GE) mosquitoes have been proposed as a public health measure against the high incidence of mosquito-borne diseases among the poor in regions of the global South. While uncertainties as well as risks for humans and ecosystems are entailed by the open-release of GE mosquitoes, a powerful global health governance non-state organization is funding the development of and advocating the use of those bio-technologies as public health tools. In August 2016, the US Food and Drug Agency (FDA) approved the uncaged field trial of a GE Aedes aegypti mosquito in Key Haven, Florida. The FDA's decision was based on its assessment of the risks of the proposed experimental public health research project. The FDA is considered a global regulatory standard setter. So, its approval of the uncaged field trial could be used by proponents of GE mosquitoes to urge countries in the global South to permit the use of those bio-technologies.
METHOD: From a public health ethics perspective, this paper evaluates the FDA's 2016 risk assessment of the proposed uncaged field trial of the GE mosquito to determine whether it qualified as a realistic risk evaluation.
RESULTS: The FDA's risk assessment of the proposed uncaged field trial did not proximate the conditions under which the GE mosquitoes would be used in regions of the global South where there is a high prevalence of mosquito-borne diseases.
CONCLUSION: Given that health and disease have political-economic determinants, whether a risk assessment of a product is realistic or not particularly matters with respect to interventions meant for public health problems that disproportionately impact socio-economically marginalized populations. If ineffective public health interventions are adopted based on risk evaluations that do not closely mirror the conditions under which those products would actually be used, there could be public health and ethical costs for those populations.

Keywords:  Bill and Melinda Gates Foundation; Genetically engineered mosquitoes; Global Health Investment Fund; Global health governance; Mosquito-borne diseases; Neoliberal philanthropy; Regulatory agencies; Risk assessments; Social determinants of mosquito-borne diseases

DOI:  https://doi.org/10.1186/s12992-021-00760-x
Viruses. 2022 Feb 21. pii: 435. [Epub ahead of print]14(2):

Adaptive Evolution as a Driving Force of the Emergence and Re-Emergence of Mosquito-Borne Viral Diseases.

Xi Yu, Gong Cheng.

  Emerging and re-emerging mosquito-borne viral diseases impose a significant burden on global public health. The most common mosquito-borne viruses causing recent epidemics include flaviviruses in the family Flaviviridae, including Dengue virus (DENV), Zika virus (ZIKV), Japanese encephalitis virus (JEV) and West Nile virus (WNV) and Togaviridae viruses, such as chikungunya virus (CHIKV). Several factors may have contributed to the recent re-emergence and spread of mosquito-borne viral diseases. Among these important causes are the evolution of mosquito-borne viruses and the genetic mutations that make them more adaptive and virulent, leading to widespread epidemics. RNA viruses tend to acquire genetic diversity due to error-prone RNA-dependent RNA polymerases, thus promoting high mutation rates that support adaptation to environmental changes or host immunity. In this review, we discuss recent findings on the adaptive evolution of mosquito-borne viruses and their impact on viral infectivity, pathogenicity, vector fitness, transmissibility, epidemic potential and disease emergence.

Keywords:  adaptive evolution; mosquito-borne viral disease; mosquito-borne virus

DOI:  https://doi.org/10.3390/v14020435
Insects. 2022 Feb 13. pii: 195. [Epub ahead of print]13(2):

Multiplex PCR Assay for the Identification of Four Species of the Anopheles Leucosphyrus Sub-Group in Malaysia.

Sandthya Pramasivan, Jonathan Wee Kent Liew, Nantha Kumar Jeyaprakasam, Van Lun Low, Romano Ngui, Indra Vythilingam.

  The Leucosphyrus Group of mosquitoes are the major simian malaria vectors in Malaysia. Accurate species identification is required to help in curbing the spread of simian malaria. The aim of the study is to provide an accurate molecular method for identifying the four important Anopheles vector species found in Malaysia. Mosquito specimens were collected from various localities in Malaysia, where simian malaria cases were reported. DNA from 122 mosquito specimens was tested to develop a multiplex polymerase chain reaction (PCR) assay. The specificity of this assay was tested against other mosquito species. Molecular identification of the species was further confirmed by analysing the internal transcribed spacer 2 (ITS2) DNA region of the specimens. Anopheles balabacensis and An. latens showed two distinct clades in the phylogenetic tree. The multiplex PCR assay was developed based on the ITS2 region for the identification of Anopheles introlatus (298-299 bp), Anopheles latens (197-198 bp), Anopheles cracens (421-426 bp), and Anopheles balabacensis (224-228 bp). This method will be useful to accurately identify the major Anopheles Leucosphyrus Group species in Malaysia, which are difficult to identify morphologically, to determine the correct vector as well as its geographical distribution.

Keywords:  Anopheles; ITS2; Malaysia; multiplex PCR assay; simian malaria; species identification

DOI:  https://doi.org/10.3390/insects13020195
Viruses. 2022 Jan 25. pii: 233. [Epub ahead of print]14(2):

Uncovering the Burden of Dengue in Africa: Considerations on Magnitude, Misdiagnosis, and Ancestry.

Emily Mary Gainor, Eva Harris, A Desiree LaBeaud.

  Dengue is a re-emerging neglected disease of major public health importance. This review highlights important considerations for dengue disease in Africa, including epidemiology and underestimation of disease burden in African countries, issues with malaria misdiagnosis and co-infections, and potential evidence of genetic protection from severe dengue disease in populations of African descent. The findings indicate that dengue virus prevalence in African countries and populations may be more widespread than reported data suggests, and that the Aedes mosquito vectors appear to be increasing in dissemination and number. Changes in climate, population, and plastic pollution are expected to worsen the dengue situation in Africa. Dengue misdiagnosis is also a problem in Africa, especially due to the typical non-specific clinical presentation of dengue leading to misdiagnosis as malaria. Finally, research suggests that a protective genetic component against severe dengue exists in African descent populations, but further studies should be conducted to strengthen this association in various populations, taking into consideration socioeconomic factors that may contribute to these findings. The main takeaway is that Africa should not be overlooked when it comes to dengue, and more attention and resources should be devoted to this disease in Africa.

Keywords:  Aedes; Africa; ancestry; climate change; coinfection; dengue; epidemiology; misdiagnosis; mosquitoes; outbreaks

DOI:  https://doi.org/10.3390/v14020233
J Med Entomol. 2022 Feb 21. pii: tjac016. [Epub ahead of print]

Seasonality and Biting Behavior of Mansonia (Diptera, Culicidae) in Rural Settlements Near Porto Velho, State of Rondônia, Brazil.

Allan Kardec R Galardo, Andréa V Hijjar, Liliane Leite O Falcão, Dario P Carvalho, Kaio Augusto N Ribeiro, Guilherme A Silveira, Noel Fernandes S Neto, José F Saraiva.

  Mansonia (Diptera: Culicidae) are known to cause discomfort to the local populations of Amazon. Considering the fact that the effective control of these mosquitoes can only be obtained by understanding their ecology and behavior, entomological monitoring becomes essential. In view of this, mosquitoes of the genus Mansonia were collected by human landing catches (HLC) from 2015 to 2019, in four locations of Porto Velho, Rondônia, Brazil. The collections were performed inside and outside the homes, once in every four months, uninterrupted for 24 hr. Human bite indices/hour was used to analyze the hourly activity of the species for different seasons and environment (indoor and outdoor). Moreover, nonparametric Mann-Whitney tests were conducted to indicate if there were differences between exophagic and endophagic behavior. The seasonality of Mansonia species was also analyzed. Overall, 96,766 specimens were collected over five years of sampling. Mansonia titillans (Walker) was found to be the most abundant species (76.9%). The highest percentage of mosquitoes was collected in February (48.4%), followed by October (39.6%) and June (12.0%). The biting activity of the two most abundant species showed peak host seeking activity/behavior during twilight and night, more perceptible in the outdoor environment (peridomiciliary). In general, seasonality showed a tendency towards a reduction in the abundance of Mansonia in the years after 2015. Our results will be essential in the formulation of effective control methodology for Mansonia in the studied area.

Keywords:  exophilic; mosquitoes; visiting behavior

DOI:  https://doi.org/10.1093/jme/tjac016
PLoS Negl Trop Dis. 2022 Feb 22. 16(2): e0010218

Joint spatiotemporal modelling reveals seasonally dynamic patterns of Japanese encephalitis vector abundance across India.

Lydia H V Franklinos, David W Redding, Tim C D Lucas, Rory Gibb, Ibrahim Abubakar, Kate E Jones.

Predicting vector abundance and seasonality, key components of mosquito-borne disease (MBD) hazard, is essential to determine hotspots of MBD risk and target interventions effectively. Japanese encephalitis (JE), an important MBD, is a leading cause of viral encephalopathy in Asia with 100,000 cases estimated annually, but data on the principal vector Culex tritaeniorhynchus is lacking. We developed a Bayesian joint-likelihood model that combined information from available vector occurrence and abundance data to predict seasonal vector abundance for C. tritaeniorhynchus (a constituent of JE hazard) across India, as well as examining the environmental drivers of these patterns. Using data collated from 57 locations from 24 studies, we find distinct seasonal and spatial patterns of JE vector abundance influenced by climatic and land use factors. Lagged precipitation, temperature and land use intensity metrics for rice crop cultivation were the main drivers of vector abundance, independent of seasonal, or spatial variation. The inclusion of environmental factors and a seasonal term improved model prediction accuracy (mean absolute error [MAE] for random cross validation = 0.42) compared to a baseline model representative of static hazard predictions (MAE = 0.51), signalling the importance of seasonal environmental conditions in predicting JE vector abundance. Vector abundance varied widely across India with high abundance predicted in northern, north-eastern, eastern, and southern regions, although this ranged from seasonal (e.g., Uttar Pradesh, West Bengal) to perennial (e.g., Assam, Tamil Nadu). One-month lagged predicted vector abundance was a significant predictor of JE outbreaks (odds ratio 2.45, 95% confidence interval: 1.52-4.08), highlighting the possible development of vector abundance as a proxy for JE hazard. We demonstrate a novel approach that leverages information from sparse vector surveillance data to predict seasonal vector abundance-a key component of JE hazard-over large spatial scales, providing decision-makers with better guidance for targeting vector surveillance and control efforts.

DOI: https://doi.org/10.1371/journal.pntd.0010218
Malar J. 2022 Feb 23. 21(1): 63

Permethrin-treated baby wraps for the prevention of malaria: results of a randomized controlled pilot study in rural Uganda.

Ross M Boyce, Enid Muhindo, Emmanuel Baguma, Rabbison Muhindo, Bwambale Shem, Ruthly François, Sam Hawke, Bonnie E Shook-Sa, Moses Ntaro, Aisha Nalusaji, Dan Nyehangane, Raquel Reyes, Jonathan J Juliano, Mark J Siedner, Sarah G Staedke, Edgar M Mulogo.

   BACKGROUND: Progress against malaria has stalled and may even be slipping backwards in high-burden countries. This is due to a range of factors including insecticide resistance and mosquito feeding behaviours that limit contact with widely-employed interventions including long-lasting insecticidal nets and indoor-residual spraying. Thus, further innovations in malaria control are urgently needed.
METHODS: The pilot was a randomized, placebo-controlled pilot study of permethrin-treated baby wraps-known locally as lesus-in children 6-18 months of age at a single site in rural western Uganda. Fifty mother-infant pairs were assigned to permethrin-treated or untreated lesus in a 1:1 allocation. Participants and clinical staff were blinded to group assignments through use of sham treatment and re-treatment of lesus. Participants attended scheduled clinic visits every 2 weeks for a total 12 weeks. The primary outcome of interest was the safety of the intervention, assessed as changes in the frequency of use, rates of discontinuation, and incidence of adverse events, such as skin rash. Secondary outcomes included acceptability and feasibility of the intervention as measured through participant satisfaction and completion of study activities, respectively.
RESULTS: Overall, rates of retention and participation were relatively high with 86.0% (43 of 50) of participants completing all scheduled visits, including 18 (75.0%) and 25 (96.2%) in the intervention and control arms respectively. By the conclusion of the 12-week follow-up period, one adverse event (0.35 events per 100 person-weeks, one-sided 95% CI 0.0-1.65) was reported. Satisfaction with the lesu was high in both groups. In each study arm, there were five incident RDT positive results, but the only PCR-positive results were observed in the control group (n = 2).
CONCLUSIONS: Permethrin-treated baby wraps were well-tolerated and broadly acceptable. Adverse events were infrequent and mild. These findings support future trials seeking to determine the efficacy of treated wraps to prevent P. falciparum malaria infection in young children as a complementary tool to existing household-based interventions.
TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04102592, Registered 25 September 2019. Available at: https://clinicaltrials.gov/ct2/show/NCT04102592.

Keywords:  Insecticide-treated clothing; Malaria; Permethrin; Plasmodium; Prevention

DOI:  https://doi.org/10.1186/s12936-022-04086-w
PLOS Glob Public Health. 2021 Dec 07. 1(12): e0000014

Plasmodium falciparum parasite prevalence in East Africa: Updating data for malaria stratification.

Victor A Alegana, Peter M Macharia, Samuel Muchiri, Eda Mumo, Elvis Oyugi, Alice Kamau, Frank Chacky, Sumaiyya Thawer, Fabrizio Molteni, Damian Rutazanna, Catherine Maiteki-Sebuguzi, Samuel Gonahasa, Abdisalan M Noor, Robert W Snow.

The High Burden High Impact (HBHI) strategy for malaria encourages countries to use multiple sources of available data to define the sub-national vulnerabilities to malaria risk, including parasite prevalence. Here, a modelled estimate of Plasmodium falciparum from an updated assembly of community parasite survey data in Kenya, mainland Tanzania, and Uganda is presented and used to provide a more contemporary understanding of the sub-national malaria prevalence stratification across the sub-region for 2019. Malaria prevalence data from surveys undertaken between January 2010 and June 2020 were assembled form each of the three countries. Bayesian spatiotemporal model-based approaches were used to interpolate space-time data at fine spatial resolution adjusting for population, environmental and ecological covariates across the three countries. A total of 18,940 time-space age-standardised and microscopy-converted surveys were assembled of which 14,170 (74.8%) were identified after 2017. The estimated national population-adjusted posterior mean parasite prevalence was 4.7% (95% Bayesian Credible Interval 2.6-36.9) in Kenya, 10.6% (3.4-39.2) in mainland Tanzania, and 9.5% (4.0-48.3) in Uganda. In 2019, more than 12.7 million people resided in communities where parasite prevalence was predicted ≥ 30%, including 6.4%, 12.1% and 6.3% of Kenya, mainland Tanzania and Uganda populations, respectively. Conversely, areas that supported very low parasite prevalence (<1%) were inhabited by approximately 46.2 million people across the sub-region, or 52.2%, 26.7% and 10.4% of Kenya, mainland Tanzania and Uganda populations, respectively. In conclusion, parasite prevalence represents one of several data metrics for disease stratification at national and sub-national levels. To increase the use of this metric for decision making, there is a need to integrate other data layers on mortality related to malaria, malaria vector composition, insecticide resistance and bionomic, malaria care-seeking behaviour and current levels of unmet need of malaria interventions.

DOI: https://doi.org/10.1371/journal.pgph.0000014
Viruses. 2022 Jan 24. pii: 219. [Epub ahead of print]14(2):

Hyperendemic Dengue and Possible Zika Circulation in the Westernmost Region of the Indonesian Archipelago.

Harapan Harapan, Kritu Panta, Alice Michie, Timo Ernst, Suzi McCarthy, Muhsin Muhsin, Safarianti Safarianti, Tjut Mariam Zanaria, Mudatsir Mudatsir, R Tedjo Sasmono, Allison Imrie.

  The transmission of dengue and other medically important mosquito-borne viruses in the westernmost region of Indonesia is not well described. We assessed dengue and Zika virus seroprevalence in Aceh province, the westernmost area of the Indonesian archipelago. Serum samples collected from 199 randomly sampled healthy residents of Aceh Jaya in 2017 were analyzed for neutralizing antibodies by plaque reduction neutralization test (PRNT). Almost all study participants (198/199; 99.5%) presented with multitypic profiles of neutralizing antibodies to two or more DENV serotypes, indicating transmission of multiple DENV in the region prior to 2017. All residents were exposed to one or more DENV serotypes by the age of 30 years. The highest geometric mean titers were measured for DENV-4, followed by DENV-1, DENV-2 and DENV-3. Among a subset of 116 sera, 27 neutralized ZIKV with a high stringency (20 with PRNT90 > 10 and 7 with PRNT90 > 40). This study showed that DENV is hyperendemic in the westernmost region of the Indonesian archipelago and suggested that ZIKV may have circulated prior to 2017.

Keywords:  Aceh; Indonesia; PRNT; Zika; dengue; seroprevalence

DOI:  https://doi.org/10.3390/v14020219
J Infect Dev Ctries. 2022 Jan 31. 16(1): 206-212

Spatial distribution of malaria and primary healthcare in Cametá and Tucuruí, Pará state, Brazil.

Maira Cibelle da Silva Peixoto, Claudia do Socorro Carvalho Miranda, Pedro Silvestre da Silva Campos, Alba Lucia Ribeiro Raithy Pereira, Marília de Souza Araújo, Emerson Cordeiro Morais, Roberto Carlos Figueiredo, Adriana Veiga da Conceição Silva, João Sérgio de Sousa Oliveira, Nelson Veiga Gonçalves.

   INTRODUCTION: Malaria cases in Brazil are concentrated in the Amazon region. In the state of Pará, malaria is considered an endemic disease, and the population has different levels of exposure, which contributes to different types of occurrence in the municipalities.
METHODOLOGY: A descriptive, cross-sectional, and ecological study was conducted using data from the Malaria Epidemiological Surveillance System of the municipalities of Cametá and Tucuruí, PA, Brazil, from 2014 to 2018; the Brazilian Institute of Geography and Statistics; and the National Registry of Health Institutions of the Ministry of Health. Statistical and spatial analyses of epidemiological, laboratory and public health service coverage variables were performed using the Bioestat 5.0 and ArcGis 10.5 software.
RESULTS: 11,381 Malaria cases were reported in the two municipalities. The highest percentage of case notifications was reported in brown-skinned men aged from 19 and 59 years, and who had primary education levels. The predominant occupations were farming and livestock in Cametá and domestic activity in Tucuruí. The most common diagnostic examination used was a thick blood smear, and Plasmodium vivax was the species most often encountered. The percentage of primary care coverage increased during the study period. The spatial distribution of the disease was not homogeneous, and there were clusters of cases with different densities in Cametá and Tucuruí.
CONCLUSIONS: Malaria is a public health problem in the municipalities of Cametá and Tucuruí, because of its transmission dynamics and variable spatial distribution as well as the coexistence of factors that favor the exposure of resident populations to epidemiological situations, thus reflecting health inequities.

Keywords:  epidemiology; malaria; primary healthcare; public health; spatial analysis

DOI:  https://doi.org/10.3855/jidc.15260
Microorganisms. 2022 Feb 03. pii: 354. [Epub ahead of print]10(2):

Spread of a Novel Indian Ocean Lineage Carrying E1-K211E/E2-V264A of Chikungunya Virus East/Central/South African Genotype across the Indian Subcontinent, Southeast Asia, and Eastern Africa.

Juthamas Phadungsombat, Hisham A Imad, Emi E Nakayama, Pornsawan Leaungwutiwong, Pongrama Ramasoota, Wang Nguitragool, Wasin Matsee, Watcharapong Piyaphanee, Tatsuo Shioda.

  The Indian Ocean Lineage (IOL) of the chikungunya virus (CHIKV) East/Central/South African (ECSA) genotype, which originated in Kenya, spread to the Indian ocean and the Indian subcontinent, and then expanded through Southeast Asia in the previous decade. It carried an adaptive mutation E1-A226V, which enhances CHIKV replication in Aedes albopictus. However, the IOL CHIKV of the most recent outbreaks during 2016-2020 in India, Pakistan, Bangladesh, the Maldives, Myanmar, Thailand, and Kenya lacked E1-A226V but carried E1-K211E and E2-V264A. Recent CHIKV genome sequences of the Maldives and Thailand were determined, and their phylogenetic relationships were further investigated together with IOL sequences reported in 2004-2020 in the database. The results showed that the ancestral IOLs diverged to a sub-lineage E1-K211E/E2-V264A, probably in India around 2008, and caused sporadic outbreaks in India during 2010-2015 and in Kenya in 2016. The massive expansion of this new sub-lineage occurred after the acquisition of E1-I317V in other neighboring and remote regions in 2014-2020. Additionally, the phylogenetic tree indicated that independent clades formed according to the geographical regions and introduction timing. The present results using all available partial or full sequences of the recent CHIKVs emphasized the dynamics of the IOL sub-lineages in the Indian subcontinent, Southeast Asia, and Eastern Africa.

Keywords:  East/Central/South African (ECSA) genotype; Indian Ocean Lineage; chikungunya virus; molecular clock analysis; mosquito; mutation; outbreak

DOI:  https://doi.org/10.3390/microorganisms10020354
PLoS One. 2022 ;17(2): e0263836

Identification of a biological form in the Anopheles stephensi laboratory colony using the odorant-binding protein 1 intron I sequence.

Jehangir Khan, Saber Gholizadeh, Dongjing Zhang, Gang Wang, Yan Guo, Xiaoying Zheng, Zhongdao Wu, Yu Wu.

BACKGROUND: Anopheles stephensi Listen (1901) is a major vector of malaria in Asia and has recently been found in some regions of Africa. The An. stepehnsi species complex is suspected to have three sibling species: type, intermediate, and mysorensis, each with its own vector competence to the malaria parasite and ecology. To identify the members of the species complex in our An. stephensi insectary colony, we used the morphological features of eggs and genetic markers such as AnsteObp1 (Anopheles stephensi odorant binding protein 1), mitochondrial oxidases subunit 1 and 2 (COI and COII), and nuclear internal transcribed spacer 2 locus (ITS2).
METHODS: Eggs were collected from individual mosquitoes (n = 50) and counted for the number of ridges under stereomicroscope. Genomic DNA was extracted from female mosquitoes. After the amplification of partial fragments of AnsteObp1, COI, COII and ITS2 genes, the PCR products were purified and sequenced. Phylogenetic analysis was performed after aligning query sequences against the submitted sequences in GenBank using MEGA 7.
RESULTS: The range of ridges number on each egg float was 12-13 that corresponds to the mysorensis form of An. stephensi. The generated COI, COII and ITS2 sequences showed 100%, 99.46% and 99.29% similarity with the sequences deposited for Chinese, Indian and Iranian strains of An. stephensi, respectively. All the generated AnsteObp1 intron I region sequences matched 100% with the sequences deposited for An. stephensi sibling species C (mysorensis form) from Iran and Afghanistan.
CONCLUSIONS: This manuscript precisely describes the morphological and molecular details of the 'var mysorensis' form of An. stephensi that could be exploited in elucidating its classification as well as in differentiation from other biotypes of the same or other anopheline species. Based on our findings, we recommend AnsteObp1 as a robust genetic marker for rapid and accurate discrimination (taxonomic identification) of the An. stephensi species complex, rather than the COI, COII, and ITS2 marker, which could only be utilized for interspecies (Anopheles) differentiation.

DOI: https://doi.org/10.1371/journal.pone.0263836
Malar J. 2022 Feb 23. 21(1): 65

Trends in malaria epidemiological factors following the implementation of current control strategies in Dangassa, Mali.

Mahamoudou Touré, Moussa Keita, Fousseyni Kané, Daouda Sanogo, Salim Kanté, Drissa Konaté, Ayouba Diarra, Nafomon Sogoba, Mamadou B Coulibaly, Sekou F Traoré, Michael Alifrangis, Mahamadou Diakité, Jeffrey G Shaffer, Donald J Krogstad, Seydou Doumbia.

   BACKGROUND: Over the past decade, three strategies have reduced severe malaria cases and deaths in endemic regions of Africa, Asia and the Americas, specifically: (1) artemisinin-based combination therapy (ACT); (2) insecticide-treated bed nets (ITNs); and, (3) intermittent preventive treatment with sulfadoxine-pyrimethamine in pregnancy (IPTp). The rationale for this study was to examine communities in Dangassa, Mali where, in 2015, two additional control strategies were implemented: ITN universal coverage and seasonal malaria chemoprevention (SMC) among children under 5 years old.
METHODS: This was a prospective study based on a rolling longitudinal cohort of 1401 subjects participating in bi-annual smear surveys for the prevalence of asymptomatic Plasmodium falciparum infection and continuous surveillance for the incidence of human disease (uncomplicated malaria), performed in the years from 2012 to 2020. Entomological collections were performed to examine the intensity of transmission based on pyrethroid spray catches, human landing catches and enzyme-linked immunosorbent assay (ELISA) testing for circumsporozoite antigen.
RESULTS: A total of 1401 participants of all ages were enrolled in the study in 2012 after random sampling of households from the community census list. Prevalence of infection was extremely high in Dangassa, varying from 9.5 to 62.8% at the start of the rainy season and from 15.1 to 66.7% at the end of the rainy season. Likewise, the number of vectors per house, biting rates, sporozoites rates, and entomological inoculation rates (EIRs) were substantially greater in Dangassa.
DISCUSSION: The findings for this study are consistent with the progressive implementation of effective malaria control strategies in Dangassa. At baseline (2012-2014), prevalence of P. falciparum was above 60% followed by a significant year-to-year decease starting in 2015. Incidence of uncomplicated infection was greater among children < 5 years old, while asymptomatic infection was more frequent among the 5-14 years old. A significant decrease in EIR was also observed from 2015 to 2020. Likewise, vector density, sporozoite rates, and EIRs decreased substantially during the study period.
CONCLUSION: Efficient implementation of two main malaria prevention strategies in Dangassa substantially contribute to a reduction of both asymptomatic and symptomatic malaria from 2015 to 2020.

Keywords:  Control strategies; Dangassa; Failure; Malaria; Mali; Plasmodium falciparum

DOI:  https://doi.org/10.1186/s12936-022-04058-0
Viruses. 2022 Feb 17. pii: 416. [Epub ahead of print]14(2):

West Nile and Usutu Virus Introduction via Migratory Birds: A Retrospective Analysis in Italy.

Elisa Mancuso, Jacopo Giuseppe Cecere, Federica Iapaolo, Annapia Di Gennaro, Massimo Sacchi, Giovanni Savini, Fernando Spina, Federica Monaco.

  The actual contribution of migratory birds in spreading West Nile (WNV) and Usutu virus (USUV) across Europe and from Africa to old countries is still controversial. In this study, we reported the results of molecular and serological surveys on migrating birds sampled during peaks of spring and autumn migration at 11 Italian sites located along important flyways, from 2012 to 2014. A total of 1335 specimens made of individual or pooled sera, and organs from 275 dead birds were tested for WNV and USUV RNA by real time PCR (RT-PCR). Furthermore, sera were tested by serum neutralization assay for detecting WNV and USUV neutralizing antibodies. Molecular tests detected WNV lineage 2 RNA in a pool made of three Song Thrush (Turdus philomelos) sera sampled in autumn, and lineage 1 in kidneys of six trans-Saharan birds sampled in spring. Neutralizing antibodies against WNV and USUV were found in 5.80% (n = 72; 17 bird species) and 0.32% (n = 4; 4 bird species) of the tested sera, respectively. Our results do not exclude the role of migratory birds as potential spreaders of WNV and USUV from Africa and Central Europe to Mediterranean areas and highlight the importance of a more extensive active surveillance of zoonotic viruses.

Keywords:  Italy; Usutu virus; West Nile virus; flavivirus; migratory birds; zoonoses

DOI:  https://doi.org/10.3390/v14020416
Nat Commun. 2022 Feb 22. 13(1): 996

Fine-scale heterogeneity in population density predicts wave dynamics in dengue epidemics.

Victoria Romeo-Aznar, Laís Picinini Freitas, Oswaldo Gonçalves Cruz, Aaron A King, Mercedes Pascual.

The spread of dengue and other arboviruses constitutes an expanding global health threat. The extensive heterogeneity in population distribution and potential complexity of movement in megacities of low and middle-income countries challenges predictive modeling, even as its importance to disease spread is clearer than ever. Using surveillance data at fine resolution from Rio de Janeiro, we document a scale-invariant pattern in the size of successive epidemics following DENV4 emergence. Using surveillance data at fine resolution following the emergence of the DENV4 dengue serotype in Rio de Janeiro, we document a pattern in the size of successive epidemics that is invariant to the scale of spatial aggregation. This pattern emerges from the combined effect of herd immunity and seasonal transmission, and is strongly driven by variation in population density at sub-kilometer scales. It is apparent only when the landscape is stratified by population density and not by spatial proximity as has been common practice. Models that exploit this emergent simplicity should afford improved predictions of the local size of successive epidemic waves.

DOI: https://doi.org/10.1038/s41467-022-28231-w