bims-mosdis Biomed News
on Mosquito distribution and disease
Issue of 2022‒11‒20
twenty-one papers selected by
Richard Halfpenny
Staffordshire University
  1. Insecticide resistance in malaria and arbovirus vectors in Papua New Guinea, 2017-2022.
  2. Culex quinquefasciatus predominance during integrated mosquito surveillance in an urban area of the Brazilian Amazon.
  3. Human and vector behaviors determine exposure to Anopheles in Namibia.
  4. Malaria vector bionomics in Taita-Taveta County, coastal Kenya.
  5. The need for larval source management accompanying urban development projects in malaria endemic areas: a case study on Bioko Island.
  6. Human behavior determinants of exposure to Anopheles vectors of malaria in Sumba, Indonesia.
  7. Aedes aegypti Totivirus identified in mosquitoes in the Brazilian Amazon region.
  8. The control of malaria vectors in rice fields: a systematic review and meta-analysis.
  9. Malaria among under-five children in Ethiopia: a systematic review and meta-analysis.
  10. Evaluation of cutaneous immune response in a controlled human in vivo model of mosquito bites.
  11. Retraction: Awareness and perception of malaria and dengue at school and college level in the district of Multan.
  12. Vector microbiome: will global climate change affect vector competence and pathogen transmission?
  13. How long is the last mile? Evaluating successful malaria elimination trajectories.
  14. Plasmodium cynomolgi in humans: current knowledge and future directions of an emerging zoonotic malaria parasite.
  15. A malaria knowledge, attitudes and practice survey in a rural community in Guinea.
  16. The history and current epidemiology of malaria in Kalimantan, Indonesia.
  17. A Chikungunya Outbreak in a Dengue-endemic Region in Rural Northern Coastal Ecuador.
  18. The use of routine health facility data for micro-stratification of malaria risk in mainland Tanzania.
  19. Is zoonotic Plasmodium vivax malaria an obstacle for disease elimination?
  20. Dengue beyond the tropics: a time-series study comprising 2015-2016 versus 2019-2020 at a children's hospital in the City of Buenos Aires.
  21. Malaria among under-five children in rural communities of Al-Mahweet governorate, Yemen.
  1. Parasit Vectors. 2022 Nov 14. 15(1): 426
    Insecticide resistance in malaria and arbovirus vectors in Papua New Guinea, 2017-2022.
    Michelle Katusele, Solomon Lagur, Nancy Endersby-Harshman, Samuel Demok, Joelyn Goi, Naomi Vincent, Muker Sakur, Absalom Dau, Lemen Kilepak, Stephen Gideon, Christine Pombreaw, Leo Makita, Ary Hoffmann, Leanne J Robinson, Moses Laman, Stephan Karl.
      BACKGROUND: Insecticide resistance (IR) monitoring is essential for evidence-based control of mosquito-borne diseases. While widespread pyrethroid resistance in Anopheles and Aedes species has been described in many countries, data for Papua New Guinea (PNG) are limited. Available data indicate that the local Anopheles populations in PNG remain pyrethroid-susceptible, making regular IR monitoring even more important. In addition, Aedes aegypti pyrethroid resistance has been described in PNG. Here, Anopheles and Aedes IR monitoring data generated from across PNG between 2017 and 2022 are presented.METHODS: Mosquito larvae were collected in larval habitat surveys and through ovitraps. Mosquitoes were reared to adults and tested using standard WHO susceptibility bioassays. DNA from a subset of Aedes mosquitoes was sequenced to analyse the voltage-sensitive sodium channel (Vssc) region for any resistance-related mutations.
    RESULTS: Approximately 20,000 adult female mosquitoes from nine PNG provinces were tested. Anopheles punctulatus sensu lato mosquitoes were susceptible to pyrethroids but there were signs of reduced mortality in some areas. Some Anopheles populations were also resistant to DDT. Tests also showed that Aedes. aegypti in PNG are resistant to pyrethroids and DDT and that there was also likelihood of bendiocarb resistance. A range of Vssc resistance mutations were identified. Aedes albopictus were DDT resistant and were likely developing pyrethroid resistance, given a low frequency of Vssc mutations was observed.
    CONCLUSIONS: Aedes aegypti is highly pyrethroid resistant and also shows signs of resistance against carbamates in PNG. Anopheles punctulatus s.l. and Ae. albopictus populations exhibit low levels of resistance against pyrethroids and DDT in some areas. Pyrethroid-only bed nets are currently the only programmatic vector control tool used in PNG. It is important to continue to monitor IR in PNG and develop proactive insecticide resistance management strategies in primary disease vectors to retain pyrethroid susceptibility especially in the malaria vectors for as long as possible.
    Keywords:  Arbovirus; Insecticide resistance; Malaria; Mosquitoes; Public health; Vector control
    DOI:  https://doi.org/10.1186/s13071-022-05493-3
  2. Braz J Biol. 2022 ;pii: S1519-69842022000100758. [Epub ahead of print]82 e266219
    Culex quinquefasciatus predominance during integrated mosquito surveillance in an urban area of the Brazilian Amazon.
    F G F Rios, C A Menezes, L R Silva, L H M Feitoza, A C A Meireles, G R Julião.
      The presence and establishment of Culicidae in urban areas increase the transmissibility of tropical diseases, since some species can participate as vectors of pathogens. Thus, this study aimed to evaluate the indoor and outdoor abundance of immature and adult populations of Culicidae at the urban area of Porto Velho, Rondônia. Mosquitoes were captured using electric aspirators and ovitraps in September and December 2018 in 27 households spread over nine neighborhoods. A total of 2,342 specimens were collected, distributed among five species, of which Culex quinquefasciatus (Say, 1823), Aedes aegypti (Linnaeus, 1762) and Aedes albopictus (Skuse, 1894) were the most abundant. Considering the sum total obtained by both techniques, more mosquitoes were captured indoors than outdoors. However, the GLM estimates for the ovitrap technique showed that immature Ae. aegypti, Ae. albopictus and Cx. quinquefasciatus were significantly more abundant in the outdoors, on average. The opposite result was observed for electrical aspiration, in which Ae. aegypti and Cx. quinquefasciatus adults were more abundant indoors. The average number of winged Ae. albopictus showed no significant difference between indoors and outdoors. Our findings corroborate the data on the abundance and incidence of these three species in other regions of Brazil, highlighting the need for continuous surveillance due to their importance in disease transmission to humans. We also demonstrated that the ovitrap is a sensitive device to monitor Cx. quinquefasciatus larvae and wild species that occasionally frequent urban areas, and thus can be used for surveillance, especially when there are budgetary constraints. Therefore, we emphasize that the combination of techniques, in addition to identifying which species and which stage of development are more frequent inside and outside households, also allows for the implementation of specific and integrated control measures.
    DOI:  https://doi.org/10.1590/1519-6984.266219
  3. Parasit Vectors. 2022 Nov 17. 15(1): 436
    Human and vector behaviors determine exposure to Anopheles in Namibia.
    Tabeth Mwema, Ophilia Lukubwe, Rosalia Joseph, Deodatus Maliti, Iitula Iitula, Stark Katokele, Petrina Uusiku, Dennis Walusimbi, Sheila Barasa Ogoma, Munya Tambo, Cara Smith Gueye, Yasmin A Williams, Elodie Vajda, Allison Tatarsky, Seth J Eiseb, Davis R Mumbengegwi, Neil F Lobo.
      BACKGROUND: Although the Republic of Namibia has significantly reduced malaria transmission, regular outbreaks and persistent transmission impede progress towards elimination. Towards an understanding of the protective efficacy, as well as gaps in protection, associated with long-lasting insecticidal nets (LLINs), human and Anopheles behaviors were evaluated in parallel in three malaria endemic regions, Kavango East, Ohangwena and Zambezi, using the Entomological Surveillance Planning Tool to answer the question: where and when are humans being exposed to bites of Anopheles mosquitoes?METHODS: Surveillance activities were conducted during the malaria transmission season in March 2018 for eight consecutive nights. Four sentinel structures per site were selected, and human landing catches and human behavior observations were consented to for a total of 32 collection nights per site. The selected structures were representative of local constructions (with respect to building materials and size) and were at least 100 m from each other. For each house where human landing catches were undertaken, a two-person team collected mosquitoes from 1800 to 0600 hours.
    RESULTS: Surveillance revealed the presence of the primary vectors Anopheles arabiensis, Anopheles gambiae sensu stricto (s.s.) and Anopheles funestus s.s., along with secondary vectors (Anopheles coustani sensu lato and Anopheles squamosus), with both indoor and outdoor biting behaviors based on the site. Site-specific human behaviors considerably increased human exposure to vector biting. The interaction between local human behaviors (spatial and temporal presence alongside LLIN use) and vector behaviors (spatial and temporal host seeking), and also species composition, dictated where and when exposure to infectious bites occurred, and showed that exposure was primarily indoors in Kavango East (78.6%) and outdoors in Ohangwena (66.7%) and Zambezi (81.4%). Human behavior-adjusted exposure was significantly different from raw vector biting rate.
    CONCLUSIONS: Increased LLIN use may significantly increase protection and reduce exposure to malaria, but may not be enough to eliminate the disease, as gaps in protection will remain both indoors (when people are awake and not using LLINs) and outdoors. Alternative interventions are required to address these exposure gaps. Focused and question-based operational entomological surveillance together with human behavioral observations may considerably improve our understanding of transmission dynamics as well as intervention efficacy and gaps in protection.
    Keywords:  Anopheles biting behavior; Human behavior; Long-lasting insecticidal net use; Namibia
    DOI:  https://doi.org/10.1186/s13071-022-05563-6
  4. Parasit Vectors. 2022 Nov 16. 15(1): 430
    Malaria vector bionomics in Taita-Taveta County, coastal Kenya.
    Jonathan Karisa, Kelly Ominde, Simon Muriu, Vanessa Munyao, Kioko Mwikali, Lawrence Babu, Zedekiah Ondieki, Brian Bartilol, Mercy Tuwei, Caroline Wanjiku, Marta Maia, Janet Midega, Martin Rono, Norbert Peshu, Charles Mbogo, Joseph M Mwangangi.
      BACKGROUND: Estimation of the composition and densities of mosquito species populations is crucial for monitoring the epidemiology of mosquito-borne diseases and provide information on local vectors to public health officials and policy-makers. The aim of this study was to evaluate malaria vector bionomics in ecologically distinct sites in Taita-Taveta County, Kenya.METHODS: Adult mosquitoes were collected using backpack aspirators and paired indoor/outdoor CDC light traps in 10 randomly selected households in six villages with distinct ecologies over a study period of 3 years. All Anopheles mosquitoes were morphotyped, and sibling species of Anopheles gambiae sensu lato (An. gambiae s.l.) were identified and separated by PCR analysis of extracted ribosomal DNA. All female anophelines were tested for sporozoite infectivity, with engorged females screened for blood-meal sources using the enzyme-linked immunosorbent assay technique. A subsample of those testing positive and those testing negative for Plasmodium in the ELISA were subjected to PCR assay.
    RESULTS: A total of eight different Anopheles species were collected both indoors and outdoors. Anopheles gambiae s.l. (82.6%, n = 5252) was the predominant species sensu lato, followed by Anopheles coustani sensu lato (An. coustani s.l.; (10.5%, n = 666) and Anopheles funestus sensu lato (An. funestus s.l.; 5.6%, n = 357). A subset of 683 mosquito samples representing An. gambiae s.l. (n = 580, approx. 11.0%) and An. funestus s.l. (n = 103, approx. 28.9%) were identified by molecular diagnostic assays into sibling species. The An. gambiae s.l. complex was composed of Anopheles arabiensis (62.5%, n = 363/580), An. gambiae sensu stricto (An. gambiae s.s.; 0.7%, n = 4/580), Anopheles merus (0.7%, n = 4/580) and Anopheles quadriannulatus (0.2%, n = 1/580), with the remaining samples (35.5%, n = 206/580) unamplified. Anopheles funestus s.l. was composed of An. rivulorum (14.6%, n = 15/103) and An. leesoni (11.6%, n = 12/103); the remaining samples were unamplified (73.8%, n = 76/103). A total of 981 samples were subjected to PCR analysis for malaria parasite detection; of these 16 (1.6%) were confirmed to be positive for Plasmodium falciparum. The overall human blood index was 0.13 (32/238).
    CONCLUSIONS: Anopheles gambiae, An. funestus and An. coustani are key malaria vectors in the Taveta region of Kenya, showing concurrent indoor and outdoor transmission. All of the vectors tested showed a higher propensity for bovine and goat blood than for human blood.
    Keywords:  Anopheles; Blood meal; Kenya; Malaria; Outdoor transmission; Sporozoite; Taveta
    DOI:  https://doi.org/10.1186/s13071-022-05527-w
  5. Malar J. 2022 Nov 14. 21(1): 328
    The need for larval source management accompanying urban development projects in malaria endemic areas: a case study on Bioko Island.
    Guillermo A García, Godwin Fuseini, Olivier Tresor Donfack, Rachel N Wofford, Jose Antonio Mba Nlang, Prudencio Bibang Efiri, Valeriano Oluy Nsue Maye, Thomas A Weppelmann, David Galick, Wonder Philip Phiri, Kylie DeBoer, Jordan M Smith, Jeremias Nzamio Mba Eyono, Matilde Riloha Rivas, Carlos A Guerra, Michael E von Fricken.
      BACKGROUND: In 2017, several new housing districts were constructed on Bioko Island, Equatorial Guinea. This case study assessed the impact construction projects had on mosquito larval habitats and the effectiveness of larval source management in reducing malaria vector density within the surrounding area.METHODS: Anopheline larval presence was assessed at 11 new construction sites by the proportion of larval habitats containing Anopheline pupae and late instar larval stages. Bacillus thuringiensis israelensis (Bti) larvicide was applied weekly to nine locations for 30 weeks, while two locations received no larvicide and acted as controls. Adult mosquito density was monitored via human landing collections in adjacent communities of six construction sites, including the two control sites.
    RESULTS: The sites that received Bti had significantly lower observation rates of both pupae (3.2% vs. 18.0%; p < 0.001) and late instar Anopheles spp. mosquitoes (14.1 vs. 43.6%; p < 0.001) compared to the two untreated sites. Anopheles spp. accounted for 67% of mosquitoes collected with human landing collections and were captured at significantly lower levels in communities adjacent to treated construction sites compared to untreated sites (p < 0.001), with an estimated 38% reduction in human biting rate (IRR: 0.62, 95% CI IRR: 0.55, 0.69). Seven months after the start of the study, untreated sites were treated due to ethical concerns given results from treatment sties, necessitating immediate Bti application. The following week, the number of habitats, the proportion of larval sites with Anopheles spp. pupae, late instars, and adult biting rates in adjacent communities to these sites all decreased to comparable levels across all sites.
    CONCLUSION: Findings suggest larval source management represents an effective intervention to suppress mosquito populations during infrastructure development. Incorporating larval source management into ongoing and planned construction initiatives represents an opportunity to fine tune vector control in response to anthropogenetic changes. Ideally, this should become standard practice in malaria-endemic regions in order to reduce viable mosquito habitats that are common by-products of construction.
    Keywords:  Anopheles; Construction; Larval habitats; Larval source management; Malaria
    DOI:  https://doi.org/10.1186/s12936-022-04362-9
  6. PLoS One. 2022 ;17(11): e0276783
    Human behavior determinants of exposure to Anopheles vectors of malaria in Sumba, Indonesia.
    Ismail E Rozi, Lepa Syahrani, Dendi H Permana, Puji B S Asih, Anggi P N Hidayati, Sully Kosasih, Farahana K Dewayanti, Rifqi Risandi, Siti Zubaidah, Michael J Bangs, Claus Bøgh, John P Grieco, Juan E Baus, Evercita Eugenio, April Monroe, Fang Liu, Nicole L Achee, Din Syafruddin, Neil F Lobo.
      Malaria vector control interventions in Sumba, Indonesia, have not been able to eliminate malaria. Human drivers of exposure to Anopheles bites were investigated as part of a larger clinical trial evaluating the impact of a spatial repellent product on malaria incidence. Human behavioral observations (HBOs) evaluating temporal and spatial presence, sleeping behaviors, and insecticide treated net (ITN) use, were collected parallel to entomological collections-indoor and outdoor human landing catches (HLCs), and house hold surveys. Data demonstrates that mosquito access to humans, enabled by structurally open houses, is evident by the similar entomological landing rates both inside and outside households. The presence of animals inside houses was associated with increased mosquito entry-however, the number of humans present inside houses was not related to increased mosquito landing. Analyzing mosquito landing rates with human behavior data enables the spatial and temporal estimation of exposure to Anopheles bites, accounting for intervention (ITN) presence and usage. Human behavior adjusted exposure to Anopheles bites was found to be highest in the early in the evening, but continued at lower levels throughout the night. Over the night, most exposure (53%) occurred when people were indoors and not under the protection of nets (asleep or awake) followed by exposure outside (44%). Characterized gaps in protection are outdoor exposure as well as exposure indoors-when awake, and when asleep and not using ITNs. Interestingly, in the primary trial, even though there was not a significant impact of the spatial repellent on vector biting rates by themselves (16%), when factoring in human behavior, there was approximately 28% less exposure in the intervention arm than in the placebo arm. The treated arm had less human behavior adjusted bites in all spaces evaluated though there was proportionally higher exposure indoors. This analysis points to the importance of using HBOs both towards understanding gaps in protection as well as how interventions are evaluated. To mitigate ongoing transmission, understanding context specific spatial and temporal exposure based on the interactions of vectors, humans and interventions would be vital for a directed evidence-based control or elimination strategy.
    DOI:  https://doi.org/10.1371/journal.pone.0276783
  7. Virus Genes. 2022 Nov 17.
    Aedes aegypti Totivirus identified in mosquitoes in the Brazilian Amazon region.
    Élcio Leal, Edcelha Soares D 'Athaide Ribeiro, Fred Julio Costa Monteiro, Julia Pantoja Marques, Diuliana Dos Santos Mendes, Vanessa S Morais, Emerson Luiz Lima Araújo, Ramendra Pati Pandey, Chung-Ming Chang, Xutao Deng, Eric Delwart, Antonio Charlys da Costa, Kledoaldo Lima.
      The totiviridae family contains viruses with double-stranded RNA genomes of 4.6-7.0 kpb, which encode a capsid protein (CP) and RNA-dependent RNA polymerase (RdRp), and they are approximately 40 nm in diameter with icosahedral symmetry. Totiviruses were first isolated from mosquitoes collected in Shaanxi Province (China). Here, we report a new Aedes aegypti Totivirus (AaTV) identified in mosquitoes from the Amazon rainforest. Mosquitoes (Diptera: Culicidae) were collected from a forest reserve belonging to the Amazon forest in the city of Macapá, Amapá state, Northern Brazil. A viral sequence with a 5748 nucleotide length that was nearly identical to Aedes aegypti Totivirus (AaTV), here named Aedes aegypti Totivirus BR59AP, was detected. A detailed molecular analysis was performed and shows that AaTV-BR59AP is highly related to the AaTV strain from the Caribbean region. We emphasize the importance of the characterization of new viruses in mosquitoes to deepen our understanding of viral diversity in insects and their potential role in disease.
    Keywords:  Aedes; Metagenomics; Mosquitoes; Totiviridae; Totivirus; Virome
    DOI:  https://doi.org/10.1007/s11262-022-01955-z
  8. Sci Rep. 2022 Nov 16. 12(1): 19694
    The control of malaria vectors in rice fields: a systematic review and meta-analysis.
    Kallista Chan, Christian Bottomley, Kazuki Saito, Jo Lines, Lucy S Tusting.
      The relatively stable aquatic conditions of irrigated lowland and rainfed rice, which is grown across 145 million hectares in more than 100 countries, are capable of generating large numbers of mosquito vectors of malaria, which causes more than 400,000 deaths per year worldwide. Many methods can control these vectors, but a systematic review has not previously been conducted. This study assesses whether larviciding, fish or intermittent irrigation can significantly reduce malaria vectors in rice fields whilst increasing rice yield. After a literature search for studies reporting the effect of larval control and rice cultivation practices on malaria vector densities in rice fields, 33 studies were eligible for meta-analysis. Larviciding was effective at reducing rice-field malaria vectors. Pooled analysis of five controlled time-series (CTS) studies with chemical insecticides showed an overall combined reduction of larval densities of 77% compared to no larviciding. Eight CTSs with biological larvicides showed a pooled reduction of 60% compared to no larviciding. Cultivating rice and fish together provided good control too: a pooled analysis of three CTSs showed an overall 82% reduction in anopheline larvae compared to no fish. Pooled analysis of four studies suggested that intermittent irrigation (using various timings and frequencies of drainage) is effective at reducing the abundance of late-stage anopheline larvae (pooled reduction = - 35%), but not overall immature abundance, compared to continuous flooding. We conclude that many interventions such as larvicides, fish and intermittent irrigation can provide riceland malaria vector control, but the critical obstacle to wider use is farmer acceptability. Future research should be led by the agricultural sector, with inputs from entomologists, to investigate malaria control co-benefits within high-yielding rice cultivation practices.
    DOI:  https://doi.org/10.1038/s41598-022-24055-2
  9. Malar J. 2022 Nov 16. 21(1): 338
    Malaria among under-five children in Ethiopia: a systematic review and meta-analysis.
    Gebeyaw Biset, Abay Woday Tadess, Kirubel Dagnaw Tegegne, Lehulu Tilahun, Natnael Atnafu.
      BACKGROUND: Globally, malaria is among the leading cause of under-five mortality and morbidity. Despite various malaria elimination strategies being implemented in the last decades, malaria remains a major public health concern, particularly in tropical and sub-tropical regions. Furthermore, there have been limited and inconclusive studies in Ethiopia to generate information for action towards malaria in under-five children. Additionally, there is a considerable disparity between the results of the existing studies. Therefore, the pooled estimate from this study will provide a more conclusive result to take evidence-based interventional measures against under-five malaria.METHODS: The protocol of this review is registered at PROSPERO with registration number CRD42020157886. All appropriate databases and grey literature were searched to find relevant articles. Studies reporting the prevalence or risk factors of malaria among under-five children were included. The quality of each study was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS). Data was extracted using Microsoft Excel 2016 and analysis was done using STATA 16.0 statistical software. The pooled prevalence and its associated factors of malaria were determined using a random effect model. Heterogeneity between studies was assessed using the Cochrane Q-test statistics and I2 test. Furthermore, publication bias was checked by the visual inspection of the funnel plot and using Egger's and Begg's statistical tests.
    RESULTS: Twelve studies with 34,842 under-five children were included. The pooled prevalence of under-five malaria was 22.03% (95% CI 12.25%, 31.80%). Lack of insecticide-treated mosquito net utilization (AOR: 5.67, 95% CI 3.6, 7.74), poor knowledge of child caretakers towards malaria transmission (AOR: 2.79, 95% CI 1.70, 3.89), and living near mosquito breeding sites (AOR: 5.05, 95% CI 2.92, 7.19) were risk factors of under-five malaria.
    CONCLUSION: More than one in five children aged under five years were infected with malaria. This suggests the rate of under-five malaria is far off the 2030 national malaria elimination programme of Ethiopia. The Government should strengthen malaria control strategies such as disseminating insecticide-treated mosquito nets (ITNs), advocating the utilization of ITNs, and raising community awareness regarding malaria transmission.
    Keywords:  Ethiopia; Malaria; Meta-analysis; Systematic review; Under-five children
    DOI:  https://doi.org/10.1186/s12936-022-04370-9
  10. Nat Commun. 2022 Nov 17. 13(1): 7036
    Evaluation of cutaneous immune response in a controlled human in vivo model of mosquito bites.
    David Guerrero, Hoa Thi My Vo, Chanthap Lon, Jennifer A Bohl, Sreynik Nhik, Sophana Chea, Somnang Man, Sokunthea Sreng, Andrea R Pacheco, Sokna Ly, Rathanak Sath, Sokchea Lay, Dorothée Missé, Rekol Huy, Rithea Leang, Hok Kry, Jesus G Valenzuela, Fabiano Oliveira, Tineke Cantaert, Jessica E Manning.
      Mosquito-borne viruses are a growing global threat. Initial viral inoculation occurs in the skin via the mosquito 'bite', eliciting immune responses that shape the establishment of infection and pathogenesis. Here we assess the cutaneous innate and adaptive immune responses to controlled Aedes aegypti feedings in humans living in Aedes-endemic areas. In this single-arm, cross-sectional interventional study (trial registration #NCT04350905), we enroll 30 healthy adult participants aged 18 to 45 years of age from Cambodia between October 2020 and January 2021. We perform 3-mm skin biopsies at baseline as well as 30 min, 4 h, and 48 h after a controlled feeding by uninfected Aedes aegypti mosquitos. The primary endpoints are measurement of changes in early and late innate responses in bitten vs unbitten skin by gene expression profiling, immunophenotyping, and cytokine profiling. The results reveal induction of neutrophil degranulation and recruitment of skin-resident dendritic cells and M2 macrophages. As the immune reaction progresses T cell priming and regulatory pathways are upregulated along with a shift to T<sub>h</sub>2-driven responses and CD8<sup>+</sup> T cell activation. Stimulation of participants' bitten skin cells with Aedes aegypti salivary gland extract results in reduced pro-inflammatory cytokine production. These results identify key immune genes, cell types, and pathways in the human response to mosquito bites and can be leveraged to inform and develop novel therapeutics and vector-targeted vaccine candidates to interfere with vector-mediated disease.
    DOI:  https://doi.org/10.1038/s41467-022-34534-9
  11. PLoS One. 2022 ;17(11): e0277592
    Retraction: Awareness and perception of malaria and dengue at school and college level in the district of Multan.
    PLOS ONE Editors
      
    DOI:  https://doi.org/10.1371/journal.pone.0277592
  12. Parasitol Res. 2022 Nov 19.
    Vector microbiome: will global climate change affect vector competence and pathogen transmission?
    Daniela de Angeli Dutra, Priscila Madi Salloum, Robert Poulin.
      Vector-borne diseases are among the greatest causes of human suffering globally. Several studies have linked climate change and increasing temperature with rises in vector abundance, and in the incidence and geographical distribution of diseases. The microbiome of vectors can have profound effects on how efficiently a vector sustains pathogen development and transmission. Growing evidence indicates that the composition of vectors' gut microbiome might change with shifts in temperature. Nonetheless, due to a lack of studies on vector microbiome turnover under a changing climate, the consequences for vector-borne disease incidence are still unknown. Here, we argue that climate change effects on vector competence are still poorly understood and the expected increase in vector-borne disease transmission might not follow a relationship as simple and straightforward as past research has suggested. Furthermore, we pose questions that are yet to be answered to enhance our current understanding of the effect of climate change on vector microbiomes, competence, and, ultimately, vector-borne diseases transmission.
    Keywords:  Climate change; Malaria; Microbiome; Mosquitoes; Vector competence; Vector-borne diseases
    DOI:  https://doi.org/10.1007/s00436-022-07734-x
  13. Malar J. 2022 Nov 14. 21(1): 330
    How long is the last mile? Evaluating successful malaria elimination trajectories.
    Justin M Cohen, Deepika Kandula, David L Smith, Arnaud Le Menach.
      BACKGROUND: Many national malaria programmes have set goals of eliminating malaria, but realistic timelines for achieving this goal remain unclear. In this investigation, historical data are collated on countries that successfully eliminated malaria to assess how long elimination has taken in the past, and thus to inform feasible timelines for achieving it in the future.METHODS: Annual malaria case series were sought for 56 successful elimination programmes through a non-systematic review. Up to 40 years of annual case counts were compiled leading up to the first year in which zero locally acquired or indigenous cases were reported. To separate the period over which effective elimination efforts occurred from prior background trends, annual case totals were log transformed, and their slopes evaluated for a breakpoint in linear trend using the segmented package in R. The number of years from the breakpoint to the first year with zero cases and the decline rate over that period were then calculated. Wilcox-Mann-Whitney tests were used to evaluate whether a set of territory characteristics were associated with the timelines and decline rates.
    RESULTS: Case series declining to the first year with zero cases were compiled for 45/56 of the candidate elimination programmes, and statistically significant breakpoints were identified for 42. The median timeline from the breakpoint to the first year with zero local cases was 12 years, over which cases declined at a median rate of 54% per year. Prior to the breakpoint, the median trend was slightly decreasing with median annual decline of < 3%. Timelines to elimination were fastest among territories that lacked land boundaries, had centroids in the Tropics, received low numbers of imported cases, and had elimination certified by the World Health Organization.
    CONCLUSION: The historical case series assembled here may help countries with aspirations of malaria elimination to set feasible milestones towards this goal. Setting goals for malaria elimination on short timescales may be most appropriate in isolated, low importation settings, such as islands, while other regions aiming to eliminate malaria must consider how to sustainably fund and maintain vital case management and vector control services until zero cases are reached.
    Keywords:  Elimination; Goal setting; History; Malaria; Malaria incidence
    DOI:  https://doi.org/10.1186/s12936-022-04368-3
  14. Infection. 2022 Nov 19.
    Plasmodium cynomolgi in humans: current knowledge and future directions of an emerging zoonotic malaria parasite.
    Loick P Kojom Foko, Amit Kumar, Joseph Hawadak, Vineeta Singh.
      Plasmodium cynomolgi (Pcy), a simian malaria parasite, is a recent perfect example of emerging zoonotic transfer in human. This review summarizes the current knowledge on the epidemiology of natural Pcy infections in humans, mosquitoes and monkeys, along with its biological, clinical and drug sensitivity patterns. Knowledge gaps and further studies on Pcy in humans are also discussed. This parasite currently seems to be geographically limited in South-East Asia (SEA) with a global prevalence in human ranging from 0 to 1.4%. The Pcy infections were reported in local SEA populations and European travelers, and range from asymptomatic carriage to mild/moderate attacks with no evidence of pathognomonic clinical and laboratory patterns but with Pcy strain-shaped clinical differences. Geographical distribution and competence of suitable mosquito vectors and non-primate hosts, globalization, climate change, and increased intrusion of humans into the habitat of monkeys are key determinants to emergence of Pcy parasites in humans, along with its expansion outside SEA. Sensitization/information campaigns coupled with training and assessment sessions of microscopists and clinicians on Pcy are greatly needed to improve data on the epidemiology and management of human Pcy infection. There is a need for development of sensitive and specific molecular tools for individual diagnosis and epidemiological studies. The development of safe and efficient anti-hypnozoite drugs is the main therapeutic challenge for controlling human relapsing malaria parasites. Experience gained from P. knowlesi malaria, development of integrated measures and strategies-ideally with components related to human, monkeys, mosquito vectors, and environment-could be very helpful to prevent emergence of Pcy malaria in humans through disruption of transmission chain from monkeys to humans and ultimately contain its expansion in SEA and potential outbreaks in a context of malaria elimination.
    Keywords:  Biology; Clinical patterns; Drug sensitivity; Emerging zoonosis; Epidemiology; Future directions; Malaria; Plasmodium cynomolgi
    DOI:  https://doi.org/10.1007/s15010-022-01952-2
  15. Malar J. 2022 Nov 14. 21(1): 329
    A malaria knowledge, attitudes and practice survey in a rural community in Guinea.
    Nirmal Ravi, Erin Holsted, Barclay Kadiebwe, Abigail Salthouse, Amer Sattar.
      BACKGROUND: Malaria is the top public health problem in the Republic of Guinea, with more than 4 million cases and 10,000 deaths in 2021 among a population of approximately 13 million. It is also the second highest cause of death there. The purpose of this quantitative survey in a rural area of Guinea was to understand knowledge, attitudes, and practices (KAP) about malaria and to assess water and sanitation practices among community members.METHODS: In 2016, the authors conducted a cross-sectional household survey in Timbi-Touni, Guinea using community workers. The survey included respondent demographic characteristics, malaria knowledge, child health, water and sanitation, and health services access. Malaria knowledge and sleeping under bed nets were the primary outcome variables and multiple logistic regression was used to determine odds ratios.
    RESULTS: Majority of the respondents were women (89.41%) and had never been to school (71.18%). Slightly more than half the children were reported to have ever had malaria and 45% reported to have ever had diarrhoea. There was no statistically significant association between gender or level of education and malaria knowledge. Eighty six percent of respondents had received a free bed net during national campaigns and 61% slept under a bed net the night before the survey. Knowing mosquitoes to be the cause of malaria and receiving free bed net were significantly associated with sleeping under a bed net. There was no statistically significant association between drinking water source and malaria or diarrhoea.
    CONCLUSIONS: Both malaria and diarrhoea were considered to be serious illnesses for adults and children by nearly all respondents. Receiving free bed nets and having correct knowledge about malaria were the greatest predictors of sleeping under a bed net. Insights from this detailed KAP survey-such as focusing on radio to transmit malaria prevention information and reinforcing free malaria treatments-can guide policy makers and practitioners who design and implement malaria control and prevention measures in Guinea.
    Keywords:  Africa; Childhood; Diarrhoea; Healthcare access; Hygiene, and sanitation practices; Knowledge, attitudes, and practice (KAP) survey; Malaria; Republic of Guinea; Water
    DOI:  https://doi.org/10.1186/s12936-022-04357-6
  16. Malar J. 2022 Nov 14. 21(1): 327
    The history and current epidemiology of malaria in Kalimantan, Indonesia.
    Sri Riyati Sugiarto, J Kevin Baird, Balbir Singh, Iqbal Elyazar, Timothy M E Davis.
      Kalimantan is a part of Indonesia, which occupies the southern three-quarters of the island of Borneo, sharing a border with the Malaysian states of Sabah and Sarawak. Although most areas of Kalimantan have low and stable transmission of Plasmodium falciparum and Plasmodium vivax, there are relatively high case numbers in the province of East Kalimantan. Two aspects of malaria endemicity in Kalimantan differentiate it from the rest of Indonesia, namely recent deforestation and potential exposure to the zoonotic malaria caused by Plasmodium knowlesi that occurs in relatively large numbers in adjacent Malaysian Borneo. In the present review, the history of malaria and its current epidemiology in Kalimantan are examined, including control and eradication efforts over the past two centuries, mosquito vector prevalence, anti-malarial use and parasite resistance, and the available data from case reports of knowlesi malaria and the presence of conditions which would support transmission of this zoonotic infection.
    Keywords:  Epidemiology; History; Kalimantan; Malaria; Plasmodium knowlesi
    DOI:  https://doi.org/10.1186/s12936-022-04366-5
  17. Am J Trop Med Hyg. 2022 Nov 14. pii: tpmd220296. [Epub ahead of print]
    A Chikungunya Outbreak in a Dengue-endemic Region in Rural Northern Coastal Ecuador.
    Sully Márquez, Gwenyth O Lee, Paulina Andrade, Julio Zuniga, Gabriel Trueba, Joseph N S Eisenberg, Josefina Coloma.
      Dengue virus (DENV) reemerged in the Americas in the 1980s and 1990s, whereas chikungunya virus (CHIKV) emerged in 2014. Although CHIKV produced large epidemics from 2014 to 2017, dengue fever has been the prominent arboviral disease identified through passive surveillance, bringing to question the degree to which cases are misdiagnosed. To address this concern, we conducted an active household-based surveillance of arboviral-like illnesses in six rural and remote communities in northern coastal Ecuador from May 2019 to February 2020. Although passive surveillance conducted by the Ecuadorian Ministry of Health reported only DENV cases in the region, more than 70% of the arbovirus-like illnesses detected by active surveillance in our study were positive for CHIKV. These findings underline the need for active surveillance of arboviral infections with laboratory confirmation, especially in rural communities where arboviral illnesses are more likely to be underreported.
    DOI:  https://doi.org/10.4269/ajtmh.22-0296
  18. Malar J. 2022 Nov 18. 21(1): 345
    The use of routine health facility data for micro-stratification of malaria risk in mainland Tanzania.
    Sumaiyya G Thawer, Monica Golumbeanu, Khalifa Munisi, Sijenunu Aaron, Frank Chacky, Samwel Lazaro, Ally Mohamed, Noela Kisoka, Christian Lengeler, Fabrizio Molteni, Amanda Ross, Robert W Snow, Emilie Pothin.
      BACKGROUND: Current efforts to estimate the spatially diverse malaria burden in malaria-endemic countries largely involve the use of epidemiological modelling methods for describing temporal and spatial heterogeneity using sparse interpolated prevalence data from periodic cross-sectional surveys. However, more malaria-endemic countries are beginning to consider local routine data for this purpose. Nevertheless, routine information from health facilities (HFs) remains widely under-utilized despite improved data quality, including increased access to diagnostic testing and the adoption of the electronic District Health Information System (DHIS2). This paper describes the process undertaken in mainland Tanzania using routine data to develop a high-resolution, micro-stratification risk map to guide future malaria control efforts.METHODS: Combinations of various routine malariometric indicators collected from 7098 HFs were assembled across 3065 wards of mainland Tanzania for the period 2017-2019. The reported council-level prevalence classification in school children aged 5-16 years (PfPR5-16) was used as a benchmark to define four malaria risk groups. These groups were subsequently used to derive cut-offs for the routine indicators by minimizing misclassifications and maximizing overall agreement. The derived-cutoffs were converted into numbered scores and summed across the three indicators to allocate wards into their overall risk stratum.
    RESULTS: Of 3065 wards, 353 were assigned to the very low strata (10.5% of the total ward population), 717 to the low strata (28.6% of the population), 525 to the moderate strata (16.2% of the population), and 1470 to the high strata (39.8% of the population). The resulting micro-stratification revealed malaria risk heterogeneity within 80 councils and identified wards that would benefit from community-level focal interventions, such as community-case management, indoor residual spraying and larviciding.
    CONCLUSION: The micro-stratification approach employed is simple and pragmatic, with potential to be easily adopted by the malaria programme in Tanzania. It makes use of available routine data that are rich in spatial resolution and that can be readily accessed allowing for a stratification of malaria risk below the council level. Such a framework is optimal for supporting evidence-based, decentralized malaria control planning, thereby improving the effectiveness and allocation efficiency of malaria control interventions.
    Keywords:  Malaria; Micro-stratification; Routine data; Tanzania
    DOI:  https://doi.org/10.1186/s12936-022-04364-7
  19. Malar J. 2022 Nov 17. 21(1): 343
    Is zoonotic Plasmodium vivax malaria an obstacle for disease elimination?
    Bárbara Aparecida Chaves, Denise Anete Madureira de Alvarenga, Matheus de Oliveira Costa Pereira, Marcelo Gordo, Emanuelle L Da Silva, Edson Rodrigues Costa, Aline Souza de Menezes Medeiros, Igor José Martins Pedrosa, Daniela Brito, Maurício Teixeira Lima, Maria Paula Mourão, Wuelton M Monteiro, Nikos Vasilakis, Cristiana Ferreira Alves de Brito, Gisely C Melo, Marcus V G Lacerda.
      BACKGROUND: The groundwork for malaria elimination does not currently consider the potential of Plasmodium zoonotic cycles that involve non-human primates (NHPs) in sylvatic environments. Since vivax malaria is less responsive to control measures, finding Plasmodium vivax infected NHPs adds even more concern.METHODS: Both Free-living monkeys in forest fragments inside the urban area and captive monkeys from a local zoo had blood samples tested for Plasmodium species.
    RESULTS: In this study, among the Neotropical monkeys tested, three (4.4%), one captive and two free-living, were found to be naturally infected by P. vivax.
    CONCLUSION: This important finding indicates that it is necessary to estimate the extent to which P. vivax NHP infection contributes to the maintenance of malaria transmission to humans. Therefore, the discussion on wildlife conservation and management must be incorporated into the malaria elimination agenda.
    Keywords:  Malaria; Malaria elimination; Non-human primates; Plasmodium vivax; Zoonotic cycle
    DOI:  https://doi.org/10.1186/s12936-022-04349-6
  20. Arch Argent Pediatr. 2022 Dec;120(6): 384-390
    Dengue beyond the tropics: a time-series study comprising 2015-2016 versus 2019-2020 at a children's hospital in the City of Buenos Aires.
    Griselda Berberian, Guadalupe Pérez, Andrea Mangano, Daniela Borgnia, Ana Buchovsky, Marina Costa, Cintia Fabbri, Victoria Luppo, Alicia S Mistchenko, Verónica Deschutter, Claudia Botana, Soledad Martiren, Martín Brizuela, Ana P Arias, María T Rosanova.
      INTRODUCTION: Dengue is a public health problem worldwide. It was originally confined to tropical and subtropical areas, but it is now present in other regions, such as Argentina. Epidemic outbreaks have been observed in the City of Buenos Aires since 2008, with few reports in children.OBJECTIVE: To analyze and compare the clinical, epidemiological, laboratory, and evolutionary characteristics of the latest 2 dengue outbreaks outside the endemic area.
    POPULATION AND METHODS: Time-series study. Patients under 18 years of age with probable or confirmed dengue and evaluated in a children's hospital of the City of Buenos Aires during the periods 2015-2016 and 2019-2020 were included.
    RESULTS: A total of 239 patients were included; 29 (12%) had a history of travel. Their median age was 132 months (interquartile range: 102- 156). All had a fever. Other symptoms included headache in 170 (71%), myalgia in 129 (54%), and rash in 122 (51%). Forty patients (17%) had comorbidities. Warning signs were observed in 79 patients (33%); 14 (6%) developed severe dengue; 115 (45%) were hospitalized; none died. DENV-1 was the most common serotype. A history of travel and hospitalization prevailed in the first period; severe dengue and prior infection, in the second period.
    CONCLUSIONS: No patient died due to dengue in either study period. Statistically significant differences were observed in the frequency of hospitalization; a history of travel was more common in the 2015-2016 period and severe dengue, in the 2019-2020 period.
    Keywords:  child; dengue; mosquito-borne diseases
    DOI:  https://doi.org/10.5546/aap.2022.eng.384
  21. Malar J. 2022 Nov 18. 21(1): 344
    Malaria among under-five children in rural communities of Al-Mahweet governorate, Yemen.
    Mona A A Al-Quhaiti, Rashad Abdul-Ghani, Mohammed A K Mahdy, Methaq A Assada.
      BACKGROUND: Malaria burden among under-five children living in endemic areas of Yemen is largely unknown due to the lack of community-based studies. Therefore, this study determined the prevalence and risk factors associated with falciparum malaria among under-five children in rural communities of Al-Mahweet governorate, Yemen.METHODS: This community-based, cross-sectional study recruited 400 under-five children from two rural districts of Al-Mahweet governorate in December 2019. Demographic characteristics (gender, age, education and occupation of the child's parents, and household size) and risk factors associated with malaria were collected through interviews with children's caregivers using a structured questionnaire. Finger-prick blood was screened for Plasmodium falciparum and non-falciparum species using rapid diagnostic tests (RDTs), and duplicate Giemsa-stained thick and thin blood films were examined for malaria parasites. The density of asexual P. falciparum stages was also estimated. Data were then analysed, and the agreement between the results of thick-film microscopy and RDTs for diagnosing falciparum malaria was assessed using the kappa index. Statistical significance was set at a P-value of < 0.05.
    RESULTS: Plasmodium falciparum was prevalent among 9.8% (95% CI 7.0-13.1) of under-five children in the rural communities of Al-Mahweet, with a median asexual parasite density of 763 ± 2606 parasites/μl of blood (range: 132-4280) and low-to-moderate parasitaemia levels. Approximately one-third of microscopy-confirmed cases were gametocyte carriers. Multivariable logistic regression analysis confirmed that age of three years or older (AOR = 5.6, 95% CI 1.6-19.8; P = 0.007), not sleeping under a mosquito net the previous night of the survey (AOR = 8.0, 95% CI 2.4-27.4; P = 0.001), sleeping outdoors at night (AOR = 4.4, 95% CI 2.0-10.0; P < 0.001), and absence of indoor residual spraying (IRS) during the last year (AOR = 4.2, 95% CI 1.9-9.4; P < 0.001) were the independent predictors of falciparum malaria among under-five children in the rural communities of Al-Mahweet. The observed percentage agreement between thick-film microscopy and RDTs was 98.5%, with a very good agreement (k-index = 0.9) between the two methods for falciparum malaria diagnosis that was statistically significant.
    CONCLUSION: Approximately one in ten under-five children in rural communities of Al-Mahweet is infected with P. falciparum based on microscopy and RDTs. Age of three years or older, not sleeping under mosquito nets, sleeping outdoors at night and absence of IRS can independently predict falciparum malaria among them. The very good agreement between thick-film microscopy and RDTs for diagnosing falciparum malaria in children supports the usefulness of using RDTs in such resource-limited rural communities.
    Keywords:  Falciparum malaria; Prevalence; Risk factors; Under-five children; Yemen
    DOI:  https://doi.org/10.1186/s12936-022-04371-8
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