bims-mosdis 2022-12-04 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2022–12–04
nine papers selected by
Richard Halfpenny, Staffordshire University

Genome-wide SNPs reveal novel patterns of spatial genetic structure in Aedes albopictus (Diptera Culicidae) population in China.
Spatial association of Aedes aegypti with dengue fever hotspots in an endemic region.
Semi-field and surveillance data define the natural diapause timeline for Culex pipiens across the United States.
Multiple invasions, Wolbachia and human-aided transport drive the genetic variability of Aedes albopictus in the Iberian Peninsula.
Population genomics reveal distinct and diverging populations of An. minimus in Cambodia.
WHO reacts to the spread of Anopheles stephensi.
Aedes Aegypti-Insights on the Impact of Water Services.
Factors influencing consistent use of bed nets for the control of malaria among children under 5 years in Soroti District, North Eastern Uganda.
Prevention of Malaria in Pregnancy: What Do the Pregnant Women of Nigeria Know and Do about It?

Front Public Health. 2022 ;10 1028026

Genome-wide SNPs reveal novel patterns of spatial genetic structure in Aedes albopictus (Diptera Culicidae) population in China.

Yong Wei, Song He, Jiatian Wang, Peiyang Fan, Yulan He, Ke Hu, Yulan Chen, Guofa Zhou, Daibin Zhong, Xueli Zheng.

   Introduction: Since the second half of the 20th century, Aedes albopictus, a vector for more than 20 arboviruses, has spread worldwide. Aedes albopictus is the main vector of infectious diseases transmitted by Aedes mosquitoes in China, and it has caused concerns regarding public health. A comprehensive understanding of the spatial genetic structure of this vector species at a genomic level is essential for effective vector control and the prevention of vector-borne diseases.
Methods: During 2016-2018, adult female Ae. albopictus mosquitoes were collected from eight different geographical locations across China. Restriction site-associated DNA sequencing (RAD-seq) was used for high-throughput identification of single nucleotide polymorphisms (SNPs) and genotyping of the Ae. albopictus population. The spatial genetic structure was analyzed and compared to those exhibited by mitochondrial cytochrome c oxidase subunit 1 (cox1) and microsatellites in the Ae. albopictus population.
Results: A total of 9,103 genome-wide SNP loci in 101 specimens and 32 haplotypes of cox1 in 231 specimens were identified in the samples from eight locations in China. Principal component analysis revealed that samples from Lingshui and Zhanjiang were more genetically different than those from the other locations. The SNPs provided a better resolution and stronger signals for novel spatial population genetic structures than those from the cox1 data and a set of previously genotyped microsatellites. The fixation indexes from the SNP dataset showed shallow but significant genetic differentiation in the population. The Mantel test indicated a positive correlation between genetic distance and geographical distance. However, the asymmetric gene flow was detected among the populations, and it was higher from south to north and west to east than in the opposite directions.
Conclusions: The genome-wide SNPs revealed seven gene pools and fine spatial genetic structure of the Ae. albopictus population in China. The RAD-seq approach has great potential to increase our understanding of the spatial dynamics of population spread and establishment, which will help us to design new strategies for controlling vectors and mosquito-borne diseases.

Keywords:  gene pool; genetic diversity; invasive species; isolation by distance; restriction site-associated DNA sequencing (RAD-Seq)

DOI:  https://doi.org/10.3389/fpubh.2022.1028026
Heliyon. 2022 Nov;8(11): e11640

Spatial association of Aedes aegypti with dengue fever hotspots in an endemic region.

Mohiuddin Sharif, Md Abdullah Saeed Khan, Mohammad Jahid Hasan, Tanzin Naher, Sujan Rudra, Jannatul Fardous, David Gozal, Md Khalilur Rahman, Mohammad Robed Amin.

   Background and objective: Dengue is a vector-borne viral disease usually transmitted by Aedes mosquitoes. Around the world, the relationship between local vector density and frequency of dengue cases is being explored and needs further evidence. This study aimed to analyze the potential spatial relationships between the dengue vector (Aedes aegypti) and dengue cases in the megacity of Bangladesh during the 2019 dengue outbreak.
Methods: Vector density measures were used to estimate spatial associations with dengue case distribution. Location was determined for 364 dengue cases who were admitted to Dhaka Medical College Hospital over a period of 4 months. Data were collected using a semi-structured questionnaire, and prior consent was ensured before participation. The Moran global index, Getis-Ord Gi∗, ordinary least squares regression, geographically weighted regression and count data regression methods were used for spatial analysis.
Results: We found that dengue case distribution was not associated with immature Aedes aegypti mosquito (larvae) density across the city. The relationship between larval density measured by the Breteau Index (BI) and House Index (HI) with dengue cases was nonstationary and not statistically significant.
Conclusion: The location of dengue cases appears to be unrelated to vector distribution and vector density. These findings should prompt the search for other transmission risk factors.

Keywords:  Dengue; Dhaka; Hotspot; Megacity; Outbreak; Spatial analysis; Tropical disease

DOI:  https://doi.org/10.1016/j.heliyon.2022.e11640
Commun Biol. 2022 Nov 27. 5(1): 1300

Semi-field and surveillance data define the natural diapause timeline for Culex pipiens across the United States.

Eleanor N Field, John J Shepard, Mark E Clifton, Keith J Price, Bryn J Witmier, Kirk Johnson, Broox Boze, Charles Abadam, Gregory D Ebel, Philip M Armstrong, Christopher M Barker, Ryan C Smith.

Reproductive diapause serves as biological mechanism for many insects, including the mosquito Culex pipiens, to overwinter in temperate climates. While Cx. pipiens diapause has been well-studied in the laboratory, the timing and environmental signals that promote diapause under natural conditions are less understood. In this study, we examine laboratory, semi-field, and mosquito surveillance data to define the approximate timeline and seasonal conditions that contribute to Cx. pipiens diapause across the United States. While confirming integral roles of temperature and photoperiod in diapause induction, we also demonstrate the influence of latitude, elevation, and mosquito population genetics in shaping Cx. pipiens diapause incidence across the country. Coinciding with the cessation of WNV activity, these data can have important implications for mosquito control, where targeted efforts prior to diapause induction can decrease mosquito populations and WNV overwintering to reduce mosquito-borne disease incidence the following season.

DOI: https://doi.org/10.1038/s42003-022-04276-x
Sci Rep. 2022 Nov 30. 12(1): 20682

Multiple invasions, Wolbachia and human-aided transport drive the genetic variability of Aedes albopictus in the Iberian Peninsula.

Federica Lucati, Sarah Delacour, John R B Palmer, Jenny Caner, Aitana Oltra, Claudia Paredes-Esquivel, Simone Mariani, Santi Escartin, David Roiz, Francisco Collantes, Mikel Bengoa, Tomàs Montalvo, Juan Antonio Delgado, Roger Eritja, Javier Lucientes, Andreu Albó Timor, Frederic Bartumeus, Marc Ventura.

The Asian tiger mosquito, Aedes albopictus, is one of the most invasive species in the world. Native to the tropical forests of Southeast Asia, over the past 30 years it has rapidly spread throughout tropical and temperate regions of the world. Its dramatic expansion has resulted in public health concerns as a consequence of its vector competence for at least 16 viruses. Previous studies showed that Ae. albopictus spread has been facilitated by human-mediated transportation, but much remains unknown about how this has affected its genetic attributes. Here we examined the factors that contributed to shaping the current genetic constitution of Ae. albopictus in the Iberian Peninsula, where the species was first found in 2004, by combining population genetics and Bayesian modelling. We found that both mitochondrial and nuclear DNA markers showed a lack of genetic structure and the presence of worldwide dominant haplotypes, suggesting regular introductions from abroad. Mitochondrial DNA showed little genetic diversity compared to nuclear DNA, likely explained by infection with maternally transmitted bacteria of the genus Wolbachia. Multilevel models revealed that greater mosquito fluxes (estimated from commuting patterns and tiger mosquito population distribution) and spatial proximity between sampling sites were associated with lower nuclear genetic distance, suggesting that rapid short- and medium-distance dispersal is facilitated by humans through vehicular traffic. This study highlights the significant role of human transportation in shaping the genetic attributes of Ae. albopictus and promoting regional gene flow, and underscores the need for a territorially integrated surveillance across scales of this disease-carrying mosquito.

DOI: https://doi.org/10.1038/s41598-022-24963-3
Commun Biol. 2022 Nov 28. 5(1): 1308

Population genomics reveal distinct and diverging populations of An. minimus in Cambodia.

Brandyce St Laurent, Nick Harding, Nick Deason, Kolthida Oy, Chea Sok Loeun, Men Sary, Rous Sunly, Sen Nhep, Eleanor Drury, Kirk Rockett, Siv Sovannaroth, Sonia Goncalves, Dominic Kwiatkowski, Alistair Miles.

Anopheles minimus is an important malaria vector throughout its wide geographic range across Southeast Asia. Genome sequencing could provide important insights into the unique malaria transmission dynamics in this region, where many vector species feed and rest outdoors. We describe results from a study using Illumina deep whole-genome sequencing of 302 wild-caught An. minimus collected from three Cambodian provinces over several years (2010, 2014, 2016) and seasons to examine the level of population structure and genetic diversity within this species. These specimens cluster into four distinct populations of An. minimus s.s., with two populations overlapping geographically. We describe the underlying genetic diversity and divergence of these populations and investigated the genetic variation in genes known to be involved in insecticide resistance. We found strong signals of selection within these An. minimus populations, most of which were present in the two Northeastern Cambodian populations and differ from those previously described in African malaria vectors. Cambodia is the focus of the emergence and spread of drug-resistant malaria parasites, so understanding the underlying genetic diversity and resilience of the vectors of these parasites is key to implementing effective malaria control and elimination strategies. These data are publicly available as part of the MalariaGEN Vector Observatory, an open access resource of genome sequence data.

DOI: https://doi.org/10.1038/s42003-022-04259-y
Lancet Infect Dis. 2022 Dec;pii: S1473-3099(22)00750-2. [Epub ahead of print]22(12): 1672

WHO reacts to the spread of Anopheles stephensi.

Sanjeet Bagcchi.

DOI: https://doi.org/10.1016/S1473-3099(22)00750-2
Geohealth. 2022 Nov;6(11): e2022GH000653

Aedes Aegypti-Insights on the Impact of Water Services.

Carlos Novaes, Francisco Silva Pinto, Rui Cunha Marques.

  Epidemics in general and dengue in particular surcharge the health services and the economy. However, the fighting actions are circumscribed to the health sector despite the known positive economic impacts that the investments in water supply and sanitation services (WSS) may cause on society and public health. Besides the fact that urban WSS infrastructure is closely linked to disease prevention, in Brazil, the user's perception and demand are very few and many institutional aspects, like the integration between local WSS, health, environment, and development of city councils, need to be improved and better aligned. In this way, disease control and vector density reduction remain challenges to be overcome. This article addresses the need for greater institutionalization of urban WSS relating them to health aspects from official data. It concludes that the negative impacts of lacking universal access to WSS on dengue and other mosquito diseases are dispersed in all cities, regions, and populations regardless of their degree of development. Furthermore, contrary to what is normally emphasized, the analysis carried out shows that the lack of urban stormwater management systems may be an important component of WSS in preventing the proliferation of dengue disease.

Keywords:  dengue fever; epidemic; public health; urban drainage; water services

DOI:  https://doi.org/10.1029/2022GH000653
Malar J. 2022 Dec 02. 21(1): 363

Factors influencing consistent use of bed nets for the control of malaria among children under 5 years in Soroti District, North Eastern Uganda.

Anne Ruth Akello, John Paul Byagamy, Samuel Etajak, Charles Stephen Okadhi, Adoke Yeka.

   BACKGROUND: The use of insecticide-treated bed nets has been proven to be effective in reducing malaria transmission in highly endemic areas. Use of long-lasting insecticidal nets (LLINs) has been embraced by many malaria endemic countries. LLINs are up to 95% effective in inhibiting blood feeding, when used consistently even after 7 years. The challenge, however, is enhancing their consistent use, especially by the most vulnerable groups (children under 5 years and pregnant women). The study established factors associated with consistent use of bed nets for malaria control among children under 5 years in Soroti district.
METHODS: The study employed a cross-sectional design, with multi-stage sampling of households. A total of 400 households (HH) were sampled and the HH head in each household interviewed. Key informant interviews (KIIs) were conducted with 7 key informants who were knowledgeable on the subject matter. Data analysis was done using SPSS 17.0 at Univariate, Bivariate and Multivariable levels; after entry and cleaning. Key informants' data were summarized manually; verbatim quotes and text used to reinforce quantitative data in line with objectives.
RESULTS: Only 56.8% of the 690 children under 5 years used bed nets consistently. The factors affecting consistent bed net use were age of the child, their use of bed nets the previous night, occupation of caretaker, respondents' perceived susceptibility, perceived risk of getting malaria, size and shape of the bed nets. Rectangular nets were difficult to hang daily in huts according to most key informants.
CONCLUSION: Consistent bed net use among under fives is still below the RBM target of 85% by 2015 and can be enhanced by providing conical bed nets and setting aside a health education programme to emphasize the effectiveness of even one mosquito in spreading malaria at night to the entire household and ability of bed nets to stop transmission better than other methods.

Keywords:  Children under 5 years; Consistent use of bed nets; Eastern Uganda; Malaria control; Soroti district

DOI:  https://doi.org/10.1186/s12936-022-04396-z
Infect Dis Obstet Gynecol. 2022 ;2022 7061548

Prevention of Malaria in Pregnancy: What Do the Pregnant Women of Nigeria Know and Do about It?

Stephen Kalu, Laurent Cleenewerck, Kabiru AbuBakar Gulma, Devender Bhalla.

Objective: We assessed knowledge, attitude, and practice regarding two malaria prevention measures (long-lasting impregnated mosquito nets, LLINs, and intermittent preventative therapy with sulphadoxine-pyrimethamine (IPTp-SP)) among pregnant women in Nigeria.
Methods: Pregnant women selected from among the four communities of Nnewi were interviewed by using a semistructured, interviewer-administered questionnaire on the respondents' demography, knowledge of the cause, consequences, and malaria prevention methods. Also, a total of 48 focused group discussions, 24 key informant interviews, and 24 in-depth interviews were held among women leaders, village heads, pregnant women, community health workers, husbands of pregnant wives, and drug and insecticide-treated net sellers.
Results: A total of 384 women (88.0% third trimester, 90.0% literate, and 41.1% primigravidae) participated. About 80.0% suffered from malaria during their current pregnancy. The majority was aware of the cause of malaria, local name of malaria, mode of transmission, risk of malaria among pregnant women, etc. However, their knowledge and attitude were inadequate regarding the symptomatology and complications of malaria in pregnancy, benefits of sleeping under the net or taking chemoprophylactic doses, or the concurrent use of both. About 80.0% had LLINs, yet only 41.5% slept under it the previous night. Only 31.0% had IPTp-SP doses under direct observation. Only 35.9% had a good understanding of IPTp-SP during pregnancy.
Conclusion: Our work presents important practice gaps associated with the prevention of malaria during pregnancy. The pregnant women seemed to be aware of the basic concepts related to malaria but that does not translate into adequate attitude and practice necessary for malaria reduction.

DOI: https://doi.org/10.1155/2022/7061548