bims-mosdis Biomed News
on Mosquito distribution and disease
Issue of 2021‒07‒25
twenty-one papers selected by
Richard Halfpenny
Staffordshire University

  1. J Vector Borne Dis. 2020 Apr-Jun;57(2):57(2): 176-181
      BACKGROUND & OBJECTIVES: The state of Punjab, India is highly endemic for dengue fever as high number of confirmed dengue cases have been reported since 2013. A better understanding of vectors distribution and their seasonal variation is necessary to control the disease. Therefore, the present study was conducted in both rural and urban areas of 11 out of 22 districts of Punjab to highlight seasonal prevalence of Aedes vector mosquitoes.METHODS: Entomological surveys were carried out in different seasons and all kinds of indoor and outdoor breeding habitats were examined and Aedes immatures were collected. The Stegomyia indices were calculated and compared from urban and rural areas in different seasons.
    RESULTS: Both vectors of dengue, i.e. Aedes aegypti and Ae. albopictus were recorded to be prevalent. Ae. aegypti mosquitoes were observed in all districts surveyed while Ae. albopictus were found only in seven districts of Punjab. The Stegomyia indices were significantly high during monsoon as compared to pre- and post- monsoon periods. Occurrence of dengue cases were found to be correlated with the Stegomyia indices.
    INTERPRETATION & CONCLUSION: This is the first detailed study of prevalence of dengue mosquito vectors in Punjab showing the presence of Ae. aegypti and Ae. albopictus in both urban and rural areas of the state, thereby demonstrating wide distribution of this vector. Different breeding habitats identified in the study should be subjected to targeted intervention such as source reduction in order to achieve effective control of dengue cases.
    Keywords:  Aedes aegypti; Aedes albopictus; India; Punjab; Stegomyia indices; breeding habitats; dengue cases
  2. Acta Trop. 2021 Jul 14. pii: S0001-706X(21)00230-8. [Epub ahead of print] 106051
      Duck Tembusu virus (DTMUV) is an emerging flavivirus that causes severe disease in avian hosts, while also affecting mammalian hosts; however, information on viral interaction with mosquito vectors for mammalian hosts is limited. Vector competence of Aedes (Ae.) aegypti and Aedes albopictus mosquitoes for DTMUV were investigated. Both Aedes mosquito species were orally infected with DK/TH/CU-1 strain of Thai DTMUV and isolated DTMUV from BALB/c mouse. Genomes of the viruses isolated from hosts and vectors were analyzed and compared with the positive virus. Findings showed that both Aedes mosquito species could serve as vectors for DTMUV with minimum viral titer in blood meal of 106 TCID50/mL. After taking blood meal with viral titer at 107 TCID50/mL, vector competence of the mosquitoes was significantly different from the lower titer in both species. Both Aedes species did not support development of the isolated viruses from mouse. A point mutation of nucleotide and amino acid was found in all isolated DTMUV from Ae. aegypti saliva, while other viruses were similar to the positive virus. Our findings demonstrated that both Ae. aegypti and Ae. albopictus had potential to transmit the virus and play important roles in the viral transmission cycle in mammalian hosts, while viral mutation occurred in Ae. aegypti mosquitoes.
    Keywords:  Aedes aegypti; Aedes albopictus; Disseminated rate; Duck Tembusu virus; Infected rate; Infective rate; Vector competence; Virus mutation
  3. Acta Trop. 2021 Jul 15. pii: S0001-706X(21)00224-2. [Epub ahead of print]222 106045
      Mosquitoes carrying endosymbiotic bacteria called Wolbachia are being released in mosquito and arbovirus control programs around the world through two main approaches: population suppression and population replacement. Open field releases of Wolbachia-infected male mosquitoes have achieved over 95% population suppression by reducing the fertility of wild mosquito populations. The replacement of populations with Wolbachia-infected females is self-sustaining and can greatly reduce local dengue transmission by reducing the vector competence of mosquito populations. Despite many successful interventions, significant questions and challenges lie ahead. Wolbachia, viruses and their mosquito hosts can evolve, leading to uncertainty around the long-term effectiveness of a given Wolbachia strain, while few ecological impacts of Wolbachia releases have been explored. Wolbachia strains are diverse and the choice of strain to release should be made carefully, taking environmental conditions and the release objective into account. Mosquito quality control, thoughtful community awareness programs and long-term monitoring of populations are essential for all types of Wolbachia intervention. Releases of Wolbachia-infected mosquitoes show great promise, but existing control measures remain an important way to reduce the burden of mosquito-borne disease.
    Keywords:  Aedes; Dengue population replacement; MASS-rearing; Population suppression; Vector control; Wolbachia
  4. J Arthropod Borne Dis. 2021 Mar;15(1): 69-81
      Background: Mosquitoes are responsible for spreading devastating parasites and pathogens causing some important infectious diseases. The present study was done to better understand and update the fauna of Culicidae and to find out the distribution and the type of their larval habitats in Kashan County.Methods: This study was done in four districts of Kashan County (Central, Qamasr, Niasar and Barzok). Mosquito larvae were collected from 23 active larval habitats using a standard 350ml capacity mosquito dipper from April to late December 2019. The collected larvae were transferred to containers containing lactophenol, and after two weeks individually mounted in Berlese's fluid on a microscope slide and identified to species by morphological characters and valid keys.
    Results: In this study, a total of 9789 larvae were collected from urban and rural areas in Kashan County. The identified genera were Anopheles, Culiseta and Culex. In this study larvae of An. turkhudi, Cx. perexiguus, Cx. mimeticus, Cx. deserticola and Cs. subochrea were collected for the first time from Kashan County.
    Conclusion: The results of this study indicate the presence and activity of different mosquito species in Kashan County that some of them are vectors of arbovirus and other vector-borne diseases.
    Keywords:  Larvae; Mosquito; Surveillance
  5. Int J Environ Res Public Health. 2021 Jul 09. pii: 7368. [Epub ahead of print]18(14):
      Since 1994, dengue fever (DF) transmission rates have increased significantly in Saudi Arabia (KSA). Climatic, geographic, and demographic conditions make KSA especially suitable for DF's spread. Still, there are insufficient strategies for controlling the Aedes species that transmit DF virus (DENV). To develop effective management strategies, it is necessary to identify Aedes species and the ecological habitat of larvae in Makkah Al-Mokarramah, KSA. We conducted a longitudinal survey of Aedes mosquitoes in 14 localities from January 2015 to December 2015. World Health Organization (WHO) inspection kits for larvae were used to detect and sample larvae, along with pictorial keys. A total of 42,981 potential Aedes larval breeding sites were surveyed. A total of 5403 (12.6%) sites had at least one water source positive for Aedes aegypti (Linnaeus) mosquitoes. Among the total of 15,133 water sources surveyed within the sampled sites, 1815 (12.0%) were positive for Aedes aegypti. Aedes aegypti was the only Aedes species identified in the course of the survey. The presence of such a large immature population may indicate an imminent outbreak of DF in the near future unless proper implementation of control and elimination of Aedes aegypti are undertaken. Additionally, the adaptation of Aedes aegypti to the arid climate of Makkah needs further investigation.
    Keywords:  Aedes aegypti mosquitoes; Makkah; dengue fever; larval ecology
  6. BMC Public Health. 2021 Jul 18. 21(1): 1417
      BACKGROUND: Wolbachia technology is a novel vector control approach that can reduce mosquito populations and the risk of mosquito-borne diseases, which has recently gained popularity amongst countries. In 2016, Singapore embarked on a multi-phased field study named Project Wolbachia - Singapore, to evaluate the use of Wolbachia technology as an Aedes aegypti mosquito population suppression tool to fight dengue. Due to the novelty of this technology in Singapore, this study aims to understand the public's acceptance and sentiments towards the use of Wolbachia technology.METHODS: Several public sentiment survey approaches - including online, face-to-face in the streets, as well as door-to-door household surveys - were conducted.
    RESULTS: The surveys conducted prior to the first field releases and implementation of the project revealed high support for the use of Wolbachia technology in Singapore. A household perception survey conducted in the interim of the first project phase was encouraging, with the majority of the respondents being aware of the project and having no concerns with the release of male Wolbachia-carrying Aedes aegypti (Wolbachia-Aedes) mosquitoes in their neighbourhood.
    CONCLUSIONS: The study reveal high support for the use of Wolbachia technology in Singapore and also provided invaluable insights that were used in the development of a public communications and engagement framework model, which thus helped to guide these elements in the subsequent phases and expansion of the project.
    Keywords:  Dengue; Perception; Singapore; Survey; Wolbachia
  7. J Vector Borne Dis. 2020 Apr-Jun;57(2):57(2): 153-160
      BACKGROUND & OBJECTIVES: Aedes aegypti is the most prominent vector for dengue virus worldwide. Accurate identification of the species and understanding its colonization pattern are essential prerequisites in vector control. Thus, the present study was aimed to genetically characterize Ae. aegypti mosquitoes collected from different regions of Sri Lanka based on mitochondrial COI gene.METHODS: Thirty-three Ae. aegypti larval samples were collected from 19 districts. A 735bp region of the mitochondrial COI gene was amplified and analyzed for genetic diversity indices. Phylogenetic trees were constructed using Sri Lankan samples and also including mosquito samples reported from other parts of the world.
    RESULTS: High genetic diversity was observed within the samples analysed (gene diversity: 0.949; average number of nucleotide differences: 6.371). There were 20 haplotypes presented within the 19 localities investigated. The phylogenetic tree derived two main clades. However, no distinguishable clustering pattern was observed in the phylogenetic tree except for the districts in the northern corner indicating extensive admixing among different populations. When samples from other countries were included in the phylogenetic tree, Anuradhapura, and Mannar samples were clustered together with samples from India, Venezuela, USA, Portugal and Cambodia while Rathnapura was clustered with Bolivia and France.
    INTERPRETATION & CONCLUSION: Our results suggest that Sri Lanka has undergone multiple invasions of Ae. aegypti from various parts of the world over an extensive period. Further, the mosquito control campaigns had not caused a significant effect on the Ae. aegypti populations which is existing in mutation-drift equilibrium.
    Keywords:  Aedes aegypti; COI gene; genetic characterization; genetic diversity; population admixture; vector control
  8. Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi. 2021 Jul 05. 33(3): 274-280
      OBJECTIVE: To understand the density, populations and habitats of malaria vector Anopheles in Guizhou Province from 2005 to 2019, so as to provide the evidence for formulating the countermeasures to tackle the risk of local transmission of imported malaria in the province.METHODS: The malaria vector Anopheles density and populations were monitored using human bait trapping and light trapping techniques in Guizhou Province from 2005 to 2019, and all captured Anopheles was morphologically identified and counted. In addition, the distribution of Anopheles habitats was investigated.
    RESULTS: During the period from 2005 through 2019, the malaria vector Anopheles density increased from early June in Guizhou Province, peaked on early July and then declined, which appeared a single peak. The greatest Anopheles density was seen on early August, 2018 [57.34 mosquitoes/(person-night)], and the lowest density was found on late October, 2009 [1.29 mosquitoes/(person-night)]. The annual mean Anopheles density slowly reduced from 17.91 mosquitoes/(person-night) in 2005 to 12.34 mosquitoes/(person-night) in 2012, with a 38.02% reduction (χ2trend = 115.04, P < 0.01), while the annual mean Anopheles density showed a tendency towards a rise from 2017 to 2019 (χ2trend = 420.00, P < 0.01). The malaria vector Anopheles was captured during the period between 19 : 00 and 7 : 00 of the next day in Guizhou Province from 2017 to 2019, with the overall density appearing a tendency towards a rise followed by a decline, and the Anopheles activity was highly frequent during the period between 19 : 00 and 21 : 00. The malaria vector Anopheles was monitored for 938 times using the light trapping method in Guizhou Province from 2005 to 2019, and a total of 52 781 Anopheles mosquitoes were captured, including 49 705 An. sinensis, 804 An. minimus, 238 An. anthropophagus, and 2 034 other Anopheles mosquitoes, with a significant difference seen in the Anopheles composition (χ2 = 165.68, P < 0.01). From 2017 to 2019, a total of 24 557 Anopheles mosquitoes were captured in human housings, outdoors and livestock housings in Guizhou Province, with 67.65% captured in livestock housings and 12.01% in human housings, and there was a significant difference in the number of Anopheles mosquitoes captured from the three types of habitats (χ2 = 55.04, P < 0.01). An. sinensis, An. minimus and An. anthropophagus were captured form all three types of habitats, in which 98.07% was An. sinensis, and 0.09% was An. anthropophagus.
    CONCLUSIONS: The population structure of malaria vector Anopheles has changed in historically malaria-endemic areas of Guizhou Province, and An. sinensis has replaced An. minimus and An. anthropophagus to become the predominant malaria vector. The malaria vector Anopheles density has shown a tendency towards a rise in Guizhou Province during the recent years, and there have been a rise in the type and number of Anopheles mosquitoes, leading to a potential risk of local transmission of imported malaria. Long-term, persistent and extensive surveillance of malaria vectors is recommended in Guizhou Province.
    Keywords:  Anopheles; Guizhou Province; Malaria; Surveillance
  9. J Arthropod Borne Dis. 2021 Mar;15(1): 21-40
      Background: Mosquitos due to their role in the transmission of different pathogens to humans are considered as an important group in the phylum Arthropoda. According to the WHO and FAO guideline different groups of insecticide applied for controlling pests in both the agricultural and public health sectors.Methods: All the data published about resistant status of the mosquitoes Anopheles, Culex, Aedes and Culiseta species were searched on PubMed, Elsevier, Web of Science, Magiran and google scholar. The objectives of this study was to review the trend of resistance to insecticides during 2000-2020 in medically important mosquitoes in Iran. The criteria for resistant are followed according to WHO guideline.
    Results: The Results showed that there are widespread, multiple resistances in the country to different organochlorine, organophosphates, carbamate and pyrethroids insecticides in the mosquitoes.
    Conclusion: The effect of pesticide residues on the environment could be a cause for selection pressure on mosquitos and lead to insecticides resistance to them. Insecticides resistance is main challenge of the vector control program. Also result will provide a guideline for control of the mosquito-borne diseases in the country as well as the world.
    Keywords:  Insecticide; Iran; Mosquito; Resistance
  10. PLoS Negl Trop Dis. 2021 Jul;15(7): e0009548
      The mosquito Aedes aegypti is the primary vector of many disease-causing viruses, including dengue (DENV), Zika, chikungunya, and yellow fever. As consequences of climate change, we expect an increase in both global mean temperatures and extreme climatic events. When temperatures fluctuate, mosquito vectors will be increasingly exposed to temperatures beyond their upper thermal limits. Here, we examine how DENV infection alters Ae. aegypti thermotolerance by using a high-throughput physiological 'knockdown' assay modeled on studies in Drosophila. Such laboratory measures of thermal tolerance have previously been shown to accurately predict an insect's distribution in the field. We show that DENV infection increases thermal sensitivity, an effect that may ultimately limit the geographic range of the virus. We also show that the endosymbiotic bacterium Wolbachia pipientis, which is currently being released globally as a biological control agent, has a similar impact on thermal sensitivity in Ae. aegypti. Surprisingly, in the coinfected state, Wolbachia did not provide protection against DENV-associated effects on thermal tolerance, nor were the effects of the two infections additive. The latter suggests that the microbes may act by similar means, potentially through activation of shared immune pathways or energetic tradeoffs. Models predicting future ranges of both virus transmission and Wolbachia's efficacy following field release may wish to consider the effects these microbes have on host survival.
  11. Nat Commun. 2021 07 19. 12(1): 4388
      Mosquito-borne diseases, such as dengue and malaria, pose significant global health burdens. Unfortunately, current control methods based on insecticides and environmental maintenance have fallen short of eliminating the disease burden. Scalable, deployable, genetic-based solutions are sought to reduce the transmission risk of these diseases. Pathogen-blocking Wolbachia bacteria, or genome engineering-based mosquito control strategies including gene drives have been developed to address these problems, both requiring the release of modified mosquitoes into the environment. Here, we review the latest developments, notable similarities, and critical distinctions between these promising technologies and discuss their future applications for mosquito-borne disease control.
  12. Cad Saude Publica. 2021 ;pii: S0102-311X2021000705006. [Epub ahead of print]37(7): e00263320
      The simultaneous circulation of dengue, Zika, and chikungunya poses major challenges for Brazil. Due to climate changes and other associated factors, more than two billion people in the world may be exposed to these arbovirus infections, according to the World Health Organization. The principal strategy for Aedes aegypti control programs is based on the Infestation Index Rapid Survey for Ae. aegypti (LIRAa), a sample survey in which the Building Infestation Index (BII) is used to prioritize areas for intervention. This study analyzed the performance of LIRAa in terms of its sensitivity for predicting dengue epidemics in municipalities in the state of Rio de Janeiro in epidemic years. Incidence rates per municipality for the years 2011, 2012, 2013, 2015, and 2016, plus the BII in October of the previous years. Scatterplots were created, aimed at an exploratory analysis and graphic visualizations of the relationship between the above-mentioned variables, as well as analyses of the Spearman correlation between the BII and the Breteau Index for each year, aimed at estimating the quality of the LIRAa. Comparative analysis of the values for the BII and the respective incidence rates in the period only indicated significant correlation between these variables in 2011/2012 (rs = 0.479; p < 0.01). There was also a correlation between BII and Breteau Index. It is urgent to rethink the parameters established by the LIRAa methodology and invest in alternative methodologies in entomological and epidemiological surveillance that reliably measure transmission risk in the territory and thus design more effective strategies to control these arbovirus infections.
  13. Am J Trop Med Hyg. 2021 Jul 19. pii: tpmd210294. [Epub ahead of print]
      La Crosse virus (LACV) is an arthropod-borne virus that can cause a nonspecific febrile illness, meningitis, or encephalitis. We reviewed U.S. LACV surveillance data for 2003-2019, including human disease cases and nonhuman infections. Overall, 318 counties in 27 states, principally in the Great Lakes, mid-Atlantic, and southeastern regions, reported LACV activity. A total of 1,281 human LACV disease cases were reported, including 1,183 (92%) neuroinvasive disease cases. The median age of cases was 8 years (range: 1 month-95 years); 1,130 (88%) were aged < 18 years, and 754 (59%) were male. The most common clinical syndromes were encephalitis (N = 960; 75%) and meningitis (N = 219, 17%). The case fatality rate was 1% (N = 15). A median of 74 cases (range: 35-130) was reported per year. The average annual national incidence of neuroinvasive disease cases was 0.02 per 100,000 persons. West Virginia, North Carolina, Tennessee, and Ohio had the highest average annual state incidences (0.16-0.61 per 100,000), accounting for 80% (N = 1,030) of cases. No animal LACV infections were reported. Nine states reported LACV-positive mosquito pools, including three states with no reported human disease cases. La Crosse virus is the most common cause of pediatric neuroinvasive arboviral disease in the United States. However, surveillance data likely underestimate LACV disease incidence. Healthcare providers should consider LACV disease in patients, especially children, with febrile illness, meningitis, or encephalitis in areas where the virus circulates and advise their patients on ways to prevent mosquito bites.
  14. Am J Trop Med Hyg. 2021 Jul 19. pii: tpmd201554. [Epub ahead of print]
      Japanese encephalitis virus (JEV) is transmitted between swine, migratory birds, and Culex mosquitoes, and has circulated indigenously in Asia for almost a century. Despite being the country with the highest JEV diversity, surveillance targeting of Indonesia's vectors is scarce. This study collected mosquitoes from several locations in Tabanan Regency, Bali Island, Indonesia. We captured and classified 3,032 adult Culex mosquitoes into seven species, with Culex vishnui subgroup mosquitoes making up approximately 90% of the total. Japanese encephalitis virus was identified by next-generation sequencing (NGS) analysis of a Cx. vishnui mosquito pool. Genetic and phylogenetic analysis revealed the JEV as genotype (G) IV. The nucleotide identity was 99% with other JEV GIV isolates obtained from swine sera in 2017 on Bali Island and from a human patient in Australia with a travel history to Bali in 2019. This finding indicated that JEV GIV persists in restricted areas and is circulating between swine-mosquito vectors.
  15. Int J Environ Res Public Health. 2021 Jul 01. pii: 7064. [Epub ahead of print]18(13):
      Pogosta disease is a mosquito-borne infection, caused by Sindbis virus (SINV), which causes epidemics of febrile rash and arthritis in Northern Europe and South Africa. Resident grouse and migratory birds play a significant role as amplifying hosts and various mosquito species, including Aedes cinereus, Culex pipiens, Cx. torrentium and Culiseta morsitans are documented vectors. As specific treatments are not available for SINV infections, and joint symptoms may persist, the public health burden is considerable in endemic areas. To predict the environmental suitability for SINV infections in Finland, we applied a suite of geospatial and statistical modeling techniques to disease occurrence data. Using an ensemble approach, we first produced environmental suitability maps for potential SINV vectors in Finland. These suitability maps were then combined with grouse densities and environmental data to identify the influential determinants for SINV infections and to predict the risk of Pogosta disease in Finnish municipalities. Our predictions suggest that both the environmental suitability for vectors and the high risk of Pogosta disease are focused in geographically restricted areas. This provides evidence that the presence of both SINV vector species and grouse densities can predict the occurrence of the disease. The results support material for public-health officials when determining area-specific recommendations and deliver information to health care personnel to raise awareness of the disease among physicians.
    Keywords:  Pogosta disease; Sindbis virus infection; disease modelling; mosquitoes; predictive mapping; vector-borne disease
  16. J Arthropod Borne Dis. 2021 Mar;15(1): 1-20
      Background: Among the blood-sucking insects, Anopheles mosquitoes have a very special position, because they transmit parasites of the genus Plasmodium, which cause malaria as one of the main vector-borne disease worldwide. The aim of this review study was to evaluate utility of complete mitochondrial genomes in phylogenetic classification of the species of Anopheles.Methods: The complete mitochondrial genome sequences belonging to 28 species of the genus Anopheles (n=32) were downloaded from NCBI. The phylogenetic trees were constructed using the ML, NJ, ME, and Bayesian inference methods.
    Results: In general, the results of the present survey revealed that the complete mitochondrial genomes act very accurately in recognition of the taxonomic and phylogenetic status of these species and provide a higher level of support than those based on individual or partial mitochondrial genes so that by using them, we can meticulously reconstruct and modify Anopheles classification.
    Conclusion: Understanding the taxonomic position of Anopheles, can be a very effective step in better planning for controlling these malaria vectors in the world and will improve our knowledge of their evolutionary biology.
    Keywords:  Anopheles; DNA; Malaria vectors; Phylogeny; Taxonomy
  17. Infect Dis Poverty. 2021 Jul 21. 10(1): 101
      BACKGROUND: Eradication of infectious disease is the sanctified public health and sustainable development goal around the world.MAIN BODY: Three antimalarial barriers were developed to control imported malarial cases, and an effective surveillance strategy known as the "1-3-7 approach" was developed to eliminate malaria from the Chinese population. From 2011 to 2019, 5254 confirmed malaria cases were reported and treated in Yunnan Province, China. Among them, 4566 cases were imported from other countries, and 688 cases were indigenous from 2011 to 2016. Since 2017, no new local malarial case has been reported in China. Thus, malaria has been completely eliminated in Yunnan Province. However, malaria is detected in overseas travellers on a regular basis, such as visitors from neighbouring Myanmar.
    CONCLUSION: Hence, the strategies should be further strengthened to maintain a robust public health infrastructure for disease surveillance and vector control programs in border areas. Such programs should be supported technically and financially by the government to avert the possibility of a malarial resurgence in Yunnan Province.
    Keywords:  China; Eliminate; Malaria; Southeast asia; Yunnan
  18. J Med Virol. 2021 Jul 21.
      The Cook Island government made several efforts to ensure zero confirmed cases and transmission of COVID-19, especially amongst visiting travellers. However, the Cook Island ministry of health has to deal with the new strain of Dengue fever outbreak, known as Dengue fever type 2 (DEN-2), by adapting several measures to control its spread, especially in the affected parts of the sub-tropical country. This paper aims to describe the Dengue fever response taken in Cook Island and suggest recommendations to control the risk of transmission in endemic parts of the world. This article is protected by copyright. All rights reserved.
    Keywords:  COVID-19; Cook Island; DEN-2; Dengue fever; Endemic; Outbreak; Travellers
  19. Malar J. 2021 Jul 19. 20(1): 321
      BACKGROUND: Several studies that aim to enhance the understanding of malaria transmission and persistence in urban settings failed to address its underlining complexity. This study aims at doing that by applying qualitative and participatory-based system analysis and mapping to elicit the system's emergent properties.METHODS: In two experts' workshops, the system was sketched and refined. This system was represented through a causal loop diagram, where the identification of leverage points was done using network analysis.
    RESULTS: 45 determinants interplaying through 56 linkages, and three subsystems: urbanization-related transmission, infection-prone behaviour and healthcare efficiency, and Plasmodium resistance were identified. Apart from the number of breeding sites and malaria-positive cases, other determinants such as drug prescription and the awareness of householders were identified by the network analysis as leverage points and emergent properties of the system of transmission and persistence of malaria.
    CONCLUSION: Based on the findings, the ongoing efforts to control malaria, such as the use of insecticide-treated bed nets and larvicide applications should continue, and new ones focusing on the public awareness and malaria literacy of city dwellers should be included. The participatory approach strengthened the legitimacy of the recommendations and the co-learning of participants.
    Keywords:  Causal loop diagram; Complex system; Emergence; Network analysis; Urban
  20. Sci Rep. 2021 Jul 23. 11(1): 15121
      Despite reductions in malaria incidence and mortality across Sub-Saharan (SSA) countries, malaria control and elimination efforts are currently facing multiple global challenges such as climate and land use change, invasive vectors, and disruptions in healthcare delivery. Although relationships between malaria risks and socioeconomic factors have been widely demonstrated, the strengths and variability of these associations have not been quantified across SSA. In this study, we used data from population-based malaria indicator surveys in SSA countries to assess spatial trends in relative and absolute socioeconomic inequalities, analyzed as social (mothers' highest educational level-MHEL) and economic (wealth index-WI) inequalities in malaria prevalence. To capture spatial variations in socioeconomic (represented by both WI and MHEL) inequalities in malaria, we calculated both the Slope Index of Inequality (SII) and Relative Index of Inequality (RII) in each administrative region. We also conducted cluster analyses based on Local Indicator of Spatial Association (LISA) to consider the spatial auto-correlation in SII and RII across regions and countries. A total of 47,404 participants in 1874 Primary Sampling Units (PSU) were analyzed across the 13 SSA countries. Our multi-country assessment provides estimations of strong socioeconomic inequalities between and within SSA countries. Such within- and between- countries inequalities varied greatly according to the socioeconomic metric and the scale used. Countries located in Eastern Africa showed a higher median Slope Index of Inequality (SII) and Relative Index of Inequality (RII) in malaria prevalence relative to WI in comparison to countries in other locations across SSA. Pockets of high SII in malaria prevalence in relation to WI and MHEL were observed in the East part of Africa. This study was able to map this wide range of malaria inequality metrics at a very local scale and highlighted the spatial clustering patterns of pockets of high and low malaria inequality values.