bims-mosdis Biomed News
on Mosquito distribution and disease
Issue of 2022‒10‒02
sixteen papers selected by
Richard Halfpenny
Staffordshire University
  1. First detection of the malaria vector Anopheles arabiensis in Côte d'Ivoire: urbanization in question.
  2. Arbovirus Screening in Mosquitoes in Emilia-Romagna (Italy, 2021) and Isolation of Tahyna Virus.
  3. Diversity and behavioral activity of Anopheles mosquitoes on the slopes of Mount Cameroon.
  4. Seagrasses extracts as potential mosquito larvicides in Saudi Arabia.
  5. Participatory approaches for raising awareness among subsistence farmers in Tanzania about the spread of insecticide resistance in malaria vectors and the possible link to improper agricultural pesticide use.
  6. Malaria outbreak in Mbale: it´s the pits! a case study.
  7. Effect of long-lasting insecticidal nets with and without piperonyl butoxide on malaria indicators in Uganda (LLINEUP): final results of a cluster-randomised trial embedded in a national distribution campaign.
  8. Assessing the impact of insecticide-treated nets in the face of insecticide resistance on malaria control.
  9. Spatial distribution and interactions between mosquitoes (Diptera: Culicidae) and climatic factors in the Amazon, with emphasis on the tribe Mansoniini.
  10. First record of the invasive mosquito species Aedes koreicus (Diptera: Culicidae) in the Czech Republic.
  11. Carbon dioxide and blood-feeding shift visual cue tracking during navigation in Aedes aegypti mosquitoes.
  12. Global trends in research on the effects of climate change on Aedes aegypti: international collaboration has increased, but some critical countries lag behind.
  13. An outbreak of malaria caused by increase in malaria breeding sites in swamps.
  14. Dengue risk zone mapping of Thiruvananthapuram district, India: a comparison of the AHP and F-AHP methods.
  15. You cannot find what you are not looking for! detecting malaria outbreaks in Uganda: a case study.
  16. Malaria frontline project: pre-intervention Malaria baseline assessment in Kano and Zamfara States, August 2016.
  1. Malar J. 2022 Sep 28. 21(1): 275
    First detection of the malaria vector Anopheles arabiensis in Côte d'Ivoire: urbanization in question.
    Florence Fournet, Akre M Adja, Kouassi A Adou, Milossé M C Dahoui, Baba Coulibaly, Konan F Assouho, Dounin D Zoh, Moussa Koné, Aboubacar Koné, Koffi L Niamien, Sylvie Cornelie, Emmanuel Tia, Nicolas Moiroux.
      BACKGROUND: Previous studies have revealed high malaria transmission in Bouaké, Côte d'Ivoire. The sociopolitical crisis in the country and the resulting environmental changes have raised the need to update existing knowledge on mosquito vector species and malaria transmission.METHODS: Adult mosquitoes were caught using the human landing catch (HLC) sampling method in Bouaké. They were collected in six districts representative of the diversity in urban landscapes. Sampling points were selected along the water network crossing the city and monitored from 2020 to 2021 to detect the presence of anopheline larvae. PCR techniques were used to ascertain the species of the Anopheles gambiae complex, Plasmodium falciparum sporozoite infection in a subset of Anopheles vectors, and insecticide resistance mechanisms in Anopheles arabiensis only.
    RESULTS: A total of 4599 Anopheles mosquitoes were collected and then identified. Anopheles gambiae sensu lato (s.l.) made up the majority of the whole collection (99%) while Anopheles funestus (0.7%), Anopheles ziemanni (0.2%), Anopheles pharoensis (0.2%) represented the remaining proportion of collection. Among the Anopheles gambiae complex, three species were identified namely An. gambiae sensu stricto (45.9%), Anopheles coluzzii (52.2%), and Anopheles arabiensis (1.9%). The first two species had already been collected in Bouaké, however this is the first time that An. arabiensis is reported in Côte d'Ivoire. Anopheles arabiensis was also collected during the larval surveys in a similar proportion (1.1%) in the same areas as the adults.
    CONCLUSIONS: This study detected the presence of An. arabiensis for the first time in Côte d'Ivoire. This species was found quite far from its usual geographic area and its expansion could be linked to the urbanization process. Although no An. arabiensis was found to be infected by Plasmodium sp., its role in malaria transmission in Bouaké has to be explored, particularly since its exophagic behaviour raises the issue of control measures and the use of insecticide-impregnated nets. The spread of this species in Côte d'Ivoire should be assessed through further research in additional towns in the country.
    Keywords:  Anopheles arabiensis; Bouaké; Côte d’Ivoire
    DOI:  https://doi.org/10.1186/s12936-022-04295-3
  2. Microbiol Spectr. 2022 Sep 27. e0158722
    Arbovirus Screening in Mosquitoes in Emilia-Romagna (Italy, 2021) and Isolation of Tahyna Virus.
    Mattia Calzolari, Paolo Bonilauri, Annalisa Grisendi, Gastone Dalmonte, Alice Vismarra, Davide Lelli, Chiara Chiapponi, Romeo Bellini, Antonio Lavazza, Michele Dottori.
      Several viruses can be transmitted by mosquitoes. We searched some of these viruses in 20,778 mosquitoes, collected in 95 traps on the plains of Emilia-Romagna (North of Italy) in 2021. We detected West Nile virus (WNV) and Usutu virus (USUV) in pools of Culex (Cx.) pipiens. In addition, we detected two insect-specific flaviviruses in three pools of Aedes (Ae.) caspius and in two of Ae. vexans. Tahyna virus (TAHV) was detected in six pools, three of Ae. caspius and three of Cx. pipiens, and one isolated strain was obtained from one of the Ae. caspius pools. Moreover, we detected TAHV in pools of several mosquito species (Ae. caspius, Ae. vexans, Ae. albopictus, Anopheles maculipennis s.l.) collected in the previous year of surveillance. Our data indicate Ae. caspius as the species most infected with TAHV in the surveyed area. Together with the likely plasticity of the cycle, we reported strong genome stability of the TAHV, probably linked to a successful adaptation of the virus to its ecological niche. Interestingly, in six pools of Cx. pipiens we detected two associated viruses among USUV, WNV, TAHV and all the three viruses in two pools. This result allows us to assume the presence of particular conditions that prompt the circulation of arboviruses, creating the conditions for viral hot spots. While no human diseases related to Tahyna virus were reported in Italy, its detection over the years suggests that it is worth investigating this virus as a potential cause of disease in humans in order to assess its health burden. IMPORTANCE We reported in this work the detection of three Arboviruses (Arthropod-borne viruses) in mosquitoes collected in Emilia-Romagna in 2021. In addition to West Nile and Usutu viruses, which were reported from more than 10 years in the study area, we detected and isolated Tahyna virus (TAHV). We also reported detections of TAHV obtained in previous years of surveillance in different species of mosquitoes. TAHV is the potential causative agent of summer influenza-like diseases and also of meningitis. Even if human cases of disease referable to this virus are not reported in Italy, its relevant presence in mosquitoes suggests investigating the possibility they could.
    Keywords:  Tahyna virus; Usutu virus; West Nile virus; insect specific flavivirus; mosquito
    DOI:  https://doi.org/10.1128/spectrum.01587-22
  3. Parasit Vectors. 2022 Sep 28. 15(1): 344
    Diversity and behavioral activity of Anopheles mosquitoes on the slopes of Mount Cameroon.
    Pilate N Kwi, Elvis E Ewane, Marcel N Moyeh, Livinus N Tangi, Vincent N Ntui, Francis Zeukeng, Denis D Sofeu-Feugaing, Eric A Achidi, Fidelis Cho-Ngwa, Alfred Amambua-Ngwa, Jude D Bigoga, Tobias O Apinjoh.
      BACKGROUND: Malaria remains endemic in Cameroon, with heterogeneous transmission related to eco-climatic variations, vector diversity and spatial distribution. The intensification of malaria prevention and control through the free distribution of insecticide-treated nets in recent years may have altered the composition, geographic distribution and natural infection rate of Anopheles species, with implications for malaria transmission dynamics. The present study seeks to assess the vectorial diversity, dynamics and infectivity across different seasons and altitudes in relationship to parasite prevalence around the slopes of Mount Cameroon, southwestern region.METHOD: Mosquitoes were sampled (indoors and outdoors) in 11 eco-epidemiological settings at low (18-197 m), intermediate (371-584 m) and high (740-1067 m) altitude by nightly human landing catches. The mosquitoes were identified morphologically and Anopheles gambiae sibling species identified by PCR. Parity status was ascertained by examining the ovaries and the entomological inoculation rates (EIR) determined by Plasmodium falciparum circumsporozoite antigen ELISA of the head-thorax. The prevalence of Plasmodium infection across target communities was assessed using rapid diagnostic tests.
    RESULTS: A total of 7327 (18.0 mosquitoes/trap/night) mosquitoes were trapped, mainly during the rainy season (5678, 77.5%) and at low altitude (3669, 50.1%). Anopheles spp. (5079, 69.3%) was the most abundant genera and An. gambiae complex (2691, 36.7%) the major vector, varying with altitude (χ2 = 183.87, df = 8, P < 0.001) and season (χ2 = 28.14, df = 4, P < 0.001). Only An. gambiae (s.s.) was identified following molecular analysis of An. gambiae complex siblings. The overall biting peak for An. gambiae complex was 2-3 a.m. Anopheles cinctus was the most abundant secondary vector in the area. The average EIR in the area was 2.08 infective bites per person per night (ib/p/n), higher at low (2.45 ib/p/n) than at intermediate altitude (1.39 ib/p/n) and during the rainy (1.76 ib/p/n) compared to the dry season (0.34 ib/p/n). Anopheles funestus was most infectious overall (28.1%, 16/57) while An. gambiae had the highest inoculation rates averaging 1.33 ib/p/n. Most Anopheles species across all altitudes and seasons were parous, highest in communities with the highest proportion of malaria parasite infections.
    CONCLUSION: Anopheles gambiae (s.s.) remains the major malaria vector in the area and An. cinctus possibly a secondary vector of the disease in the slopes of Mt. Cameroon. The seasonal and altitudinal effects on the distribution of these mosquitoes may have implications for the transmission of malaria and its control strategies in the area. Regular monitoring of the bionomics of local Anopheles vector species and targeted control interventions in the 'hotspots' is necessary to curb the prevalence of the infection and incidence of disease.
    Keywords:  Altitude; Anopheles; Diversity; Infectivity; Malaria
    DOI:  https://doi.org/10.1186/s13071-022-05472-8
  4. Saudi J Biol Sci. 2022 Dec;29(12): 103433
    Seagrasses extracts as potential mosquito larvicides in Saudi Arabia.
    Hayat S Al-Rashidi, Jazem A Mahyoub, Khalid M Alghamdi, Wafa Mohammed Al-Otaibi.
      The present study aimed to evaluate the toxic and biological effects of some extracts of seagrasses (Cymodocea rotundata; Halophila ovata& Thalassia hemprichii) against Aedes aegypti, which transmits dengue fever, and Culex pipiens, which is the dominant species of mosquitoes in the Kingdom of Saudi Arabia, as a safe method for its control. The cumulative death rate during larval development into pupae and adults was used as a criterion for evaluating tested seaweed extracts against Ae. aegypti, Cx. Pipiens. According to the obtained IC50 values ​​(the concentration that inhibits the exit of 50 % of adult mosquitoes), the results showed that C. rotundata extract (70.78 & 77.47 ppm) was more effective against A. aegypti and Cx. pipiens in comparison with H. ovata (86,98 & 95,87 ppm) and T. hemprichii (83,94 & 88,82) extracts by (1.186, 1.229, 1.146 & 1.237) fold, respectively. The results showed that the treatment with marine plant extracts against mosquito larvae of Cx. Pipiens and Ae. Aegypti gave different biological effects similar to those of other insect growth regulators (IGRs). The results also revealed the presence of morphological abnormalities in larvae that were treated with all seaweed extracts and these effects extended to all stages of growth, which caused damage to the insect without completing its life cycle. Generally, the results indicate the importance of carrying out bio-assessment tests for the pesticides that are used against mosquitoes and establishing a database to be referenced when planning control programs and making the right decision about the pesticide used.
    Keywords:  Aedes aegypti; Control; Culex pipiens; Cymodocea rotundata; Halophila ovata; Thalassia hemprichii
    DOI:  https://doi.org/10.1016/j.sjbs.2022.103433
  5. Malar J. 2022 Sep 30. 21(1): 277
    Participatory approaches for raising awareness among subsistence farmers in Tanzania about the spread of insecticide resistance in malaria vectors and the possible link to improper agricultural pesticide use.
    Nancy Stephen Matowo, Marcel Tanner, Benigni Alfred Temba, Marceline Finda, Yeromin Paul Mlacha, Jürg Utzinger, Fredros Oketch Okumu.
      BACKGROUND: Insecticide resistance is a key barrier to long-term malaria control, and it may be exacerbated by poor agricultural pesticide use. Current practices, however, do not link public health and agricultural pesticide use. This study investigated the perspectives of farmers and other stakeholders regarding the integration of agricultural and public health measures to address resistance. Additionally, the feasibility of participatory workshops to increase the farmers' understanding and participation in pesticide stewardship was assessed.METHODS: Four themes were investigated: pesticide awareness, practices, and opinions of; insecticide resistance in malaria vectors; the effectiveness of current malaria prevention tools; and the links between agricultural and public health pesticide usage. Participatory workshops and field training were held with entomologists, farmers, and agricultural specialists, focusing on agro-ecosystem practices related to pest control; and local farmers were involved in live-testing for insecticides resistance of local Anopheles mosquitoes.
    RESULTS: Most farmers (94%) considered pesticides effective, and nearly half of them (n = 198, 46.4%) could identify and name crop pests and diseases, mostly using local names. Three quarters were unaware of mosquito larvae in their fields, and only 7% considered their fields as potential sources of mosquitoes. Two thirds were uninformed of any effects that agricultural pesticides may have on mosquitoes, and three quarters had never heard of resistance in malaria mosquitoes. Experts from various sectors acknowledged that agricultural pesticides might impact malaria control through increasing resistance. They did, however, emphasize the importance of crop protection and advocated for the use of pesticides sparingly and non-chemical approaches. Farmers learnt how to discriminate between malaria vectors and non-vectors, identify agricultural pests and diseases, choose and use pesticides effectively, and conduct resistance tests during the participatory workshops.
    CONCLUSION: This study emphasizes the significance of enhancing subsistence farmers' awareness of mosquito ecology as well as merging public health and agricultural pest management measures. Participatory techniques have the potential to raise stakeholder awareness and engagement, resulting in more effective resistance management.
    Keywords:  Agricultural pesticides; Agricultural practices; Anopheles mosquitoes; Crop pests; Insecticide resistance; Malaria; Participatory learning; Tanzania
    DOI:  https://doi.org/10.1186/s12936-022-04289-1
  6. Pan Afr Med J. 2022 ;41(Suppl 1): 3
    Malaria outbreak in Mbale: it´s the pits! a case study.
    Daniel Kadobera, Gloria Bahizi, Lilian Bulage, Benon Kwesiga, Stephen Ndugwa Kabwama, Alex Riolexus Ario, Julie Roberts Harris.
      Malaria is a leading cause of morbidity and mortality in Uganda. In June 2019, the Uganda Ministry of Health through routine surveillance data analysis was notified of an increase in malaria cases in Bumbobi and Nyondo Sub-counties, Mbale District, which exceeded the action thresholds. We investigated to assess outbreak magnitude, identify transmission risk factors, and recommend evidence-based control measures. We defined a confirmed case as a positive malaria result using malaria Rapid Diagnostic Test or microscopy from 1 Jan 2019 to 30 Jun 2019 in a resident or visitor of Bumbobi or Nyondo Sub-county, Mbale District. We reviewed medical records to develop a line list for descriptive epidemiology. In a case-control study, we compared exposures between 150 case-persons and 150 age- and village-matched asymptomatic controls. We conducted environmental and entomological assessments on vector dynamics and behavior. We identified 7,891 case-persons (attack rate [AR]=26%). Females (AR=36%) were more affected than males (AR=25%). The 5-18 year age group (AR=26%) was most affected. The epidemic curve showed steady increase in malaria cases from March following intermittent rainfall from January, with short spells of no rainfall up to June. In the matched pair case-control analysis, 95% (143/150) of case-patients and 49% (73/150) of controls had soil erosion control pits near their homes that held stagnant water for several days following rainfall (AOR=18, 95%CI=7-50); Active breeding sites were found near and within homesteads with Anopheles gambiaeas the predominant vector. Increased vector breeding sites due to erosion control pits sustained by the intermittent rainfall caused this outbreak. We recommended draining of pits immediately after the rains and increasing coverage for bed-nets.
    Keywords:  Case study; Plasmodium falciparum; Uganda; malaria; outbreak
    DOI:  https://doi.org/10.11604/pamj.supp.2022.41.1.31194
  7. Lancet Infect Dis. 2022 Sep 26. pii: S1473-3099(22)00469-8. [Epub ahead of print]
    Effect of long-lasting insecticidal nets with and without piperonyl butoxide on malaria indicators in Uganda (LLINEUP): final results of a cluster-randomised trial embedded in a national distribution campaign.
    Catherine Maiteki-Sebuguzi, Samuel Gonahasa, Moses R Kamya, Agaba Katureebe, Irene Bagala, Amy Lynd, Peter Mutungi, Simon P Kigozi, Jimmy Opigo, Janet Hemingway, Grant Dorsey, Martin J Donnelly, Sarah G Staedke.
      BACKGROUND: Long-lasting insecticidal nets (LLINs) are the foundation of malaria control but resistance of mosquito vectors to pyrethroids threatens their effectiveness. We embedded a cluster-randomised trial into Uganda's 2017-18 campaign to distribute LLINs. LLINs with piperonyl butoxide (PBO) reduced parasite prevalence more effectively than conventional LLINs (without PBO) for 18 months. Here, we report the final 25-month survey results.METHODS: LLINEUP was a cluster-randomised trial conducted in 48 districts in eastern and western Uganda. 104 health subdistricts (clusters) without ongoing or planned indoor residual spraying with pirimiphos-methyl (Actellic, Basel, Switzerland) were eligible for inclusion in the trial. Clusters were randomly assigned to PBO LLINs (PermaNet 3.0 or Olyset Plus) and conventional LLINs (PermaNet 2.0 or Olyset Net) with proportionate randomisation using STATA version 14.2. LLINs were delivered from March 25, 2017, to March 18, 2018. Between April 23, 2019, and Sept 13, 2019, community surveys were conducted in 50 randomly selected households per cluster; ten households per cluster were randomly selected for entomology surveys. Mosquitoes were collected in the morning from indoor surfaces of households using Prokopack aspirators. Due to COVID-19 restrictions, only 90 of the 104 clusters were surveyed at 25 months. The primary outcome was parasite prevalence by microscopy in children aged 2-10 years, assessed in the as-treated population, determined using the results from the 6-month household survey on the type of LLINs received in each cluster. This trial is registered with ISRCTN, ISRCTN17516395, and is now completed.
    FINDINGS: In the as-treated analysis, two clusters were excluded (no predominant LLIN received) and four were reassigned; 40 PBO LLIN clusters (30 PermaNet 3.0, ten Olyset Plus) and 48 non-PBO LLIN (36 PermaNet 2.0, 12 Olyset Net) were included. Parasite prevalence was 17·1% (506 of 2958 participants) in the PBO group and 19·8% (701 of 3534) in the non-PBO group (prevalence ratio adjusted for baseline 0·80 [95% CI 0·69-0·93], p=0·0048). Comparing within-treatment group parasite prevalence to baseline, parasite prevalence ratios were lower in the PBO groups at all timepoints, but the difference was greatest at 6 months (PBO LLINs parasite prevalence at baseline 28·8% [1001 of 3472, 95% CI 27·3-30·4] vs at 6 months 12·0% [361 of 3009, 10·9-13·2], prevalence ratio [PR] 0·43 [95% CI 0·36-0·52], p<0·0001; non-PBO LLINs parasite prevalence at baseline 25·4% [1015 of 4004, 24·0-26·7] vs 6 months 14·8% [526 of 3551, 13·7-16·0], PR 0·60 [0·54-0·68], p<0·0001) and 25 months (PBO LLINs parasite prevalence at 25 months 17·1% [506 of 2958, 15·8-18·5], PR 0·63 [95% CI 0·57-0·71], p<0·0001; non-PBO LLINs parasite prevalence at 25 months 19·8% [701 of 3534, 18·5-21·2], PR 0·79 [0·73-0·86], p<0·0001).
    INTERPRETATION: In Uganda, PBO LLINs outperformed pyrethroid-only LLINs for 25 months. WHO concluded that PBO LLINs are more effective against malaria than non-PBO LLINs when resistance to pyrethroids is high and issued a conditional recommendation suggesting PBO LLINs should be deployed in areas of pyrethroid resistance.
    FUNDING: The Against Malaria Foundation, UK Department for International Development, Innovative Vector Control Consortium, and Bill and Melinda Gates Foundation.
    DOI:  https://doi.org/10.1016/S1473-3099(22)00469-8
  8. J Theor Biol. 2022 Sep 22. pii: S0022-5193(22)00272-7. [Epub ahead of print] 111281
    Assessing the impact of insecticide-treated nets in the face of insecticide resistance on malaria control.
    Calistus N Ngonghala.
      The mosquito-borne disease, malaria, continues to impose a devastating health and economic burden worldwide. In malaria-endemic areas, insecticide-treated nets (ITNs) have been useful in curtailing the burden of the disease. However, mosquito resistance to insecticides, decay in ITN efficacy, net attrition, etc., undermine the effectiveness of ITNs. In this study, mathematical models that account for asymptomatic infectious humans through a partially immune class or a separate asymptomatic infectious class, as well as insecticide resistance, and decay in ITN efficacy are proposed and analyzed. Analytical and numerical results of the models when ITN efficacy is constant show that there are parameter regimes for which a backward bifurcation occurs. Local and global sensitivity analyses are performed to identify parameters (some of which are potential targets for disease control) with the most significant influence on the control reproduction (Rc) and disease prevalence. These influential parameters include the maximum biting rate of resistant mosquitoes, ITN coverage, initial ITN efficacy against sensitive mosquitoes, the probability that an infectious mosquito (human) infects a susceptible human (mosquito), and the rate at which adult mosquitoes develop (lose) resistance to insecticides. Simulations of the models show that accounting for asymptomatic infectious humans through a separate class or not accounting for the decay in ITN efficacy over time leads to an underestimation of disease burden. In particular, if the initial efficacy of ITNs against sensitive and resistance mosquitoes is 96%, the minimum ITN coverage required to reduce Rc below one is approximately 11% (27%) lower for the case in which ITN efficacy is time-averaged (constant) for a model with a separate asymptomatic class. For the model with a partially immune class and decaying ITN efficacy, reducing Rc below one is impossible even if the entire populace uses ITNs. Furthermore, the study shows that replacing ITNs before the prescribed useful lifespan or designing ITNs with longer lifespans is important for malaria control and that piperonyl butoxide ITNs (which inhibit or reverse insecticide resistance) outperform regular ITNs in malaria control. Hence, prospects for effectively controlling malaria are enhanced by widespread use of high quality ITNs, especially if the useful lifespans of the ITNs are long enough and the ITNs are replaced before the end of their useful lifespans.
    Keywords:  Asymptomatic infection; Human behavior; Insecticide resistance; Malaria control; Mosquito behavior
    DOI:  https://doi.org/10.1016/j.jtbi.2022.111281
  9. Sci Rep. 2022 Sep 28. 12(1): 16214
    Spatial distribution and interactions between mosquitoes (Diptera: Culicidae) and climatic factors in the Amazon, with emphasis on the tribe Mansoniini.
    Cecilia Ferreira de Mello, Ronaldo Figueiró, Rosemary Aparecida Roque, Daniele Aguiar Maia, Vânia da Costa Ferreira, Anthony Érico Guimarães, Jeronimo Alencar.
      This work aimed to evaluate the spatial distribution of mosquitoes in different seasonal periods and the interaction between climatic factors and the abundance of mosquitoes, especially those belonging to the tribe Mansoniini in the area surrounding the Amazon hydroelectric production region (Jirau-HP) of Rondônia state, Brazil. Mosquito specimens were collected in May, July, October, and December 2018, and April, July, September, and November 2019, over periods of three alternating days during the hours of 6:00 p.m. to 8:00 p.m. Mosquito sampling was performed using automatic CDC and Shannon light traps. Canonical correspondence analysis (CCA), combined with Monte Carlo permutations, was used to evaluate the correlation between climatic variables and species distribution. In addition, non-metric multidimensional scaling (NMDS) was used to verify the similarity among the sampled communities from the different collections. After analyzing the total mosquito fauna at all sampling points, 46,564 specimens were identified, with Mansonia dyari showing the highest relative abundance in 2018 (35.9%). In contrast, Mansonia titillans had the highest relative abundance in 2019 (25.34%), followed by Mansonia iguassuensis (24.26%). The CCA showed that maximum temperature significantly influenced the distribution of mosquito populations in the study area (p = 0.0406). The NMDS showed that sampling carried out in the rainy and dry seasons formed two distinct groups. There was a significant correlation between species richness and cumulative precipitation 15 days before the sampling period (R2 = 58.39%; p = 0.0272). Thus, both temperature and precipitation affected mosquito population dynamics. The effect of rainfall on mosquito communities may be due to variations in habitat availability for immature forms.
    DOI:  https://doi.org/10.1038/s41598-022-20637-2
  10. Parasitol Res. 2022 Sep 30.
    First record of the invasive mosquito species Aedes koreicus (Diptera: Culicidae) in the Czech Republic.
    Jakub Vojtíšek, Oldřich Šebesta, Silvie Šikutová, Helge Kampen, Ivo Rudolf.
      Aedes koreicus is an invasive mosquito species originating from East Asia. It has recently been introduced into several countries in Southern, Central and Eastern Europe as well as Central Asia in many of which it has successfully established populations. The biology and ecological requirements of the species are largely unknown, but it is considered as a potential vector of pathogens that requires careful monitoring. We report here the first detection of Ae. koreicus in the Czech Republic, based on a citizen report.
    Keywords:  Aedes koreicus; Central Europe; Invasive species; Mosquito vector; Surveillance
    DOI:  https://doi.org/10.1007/s00436-022-07658-6
  11. Biol Lett. 2022 Sep;18(9): 20220270
    Carbon dioxide and blood-feeding shift visual cue tracking during navigation in Aedes aegypti mosquitoes.
    Elina Barredo, Joshua I Raji, Michael Ramon, Matthew DeGennaro, Jamie Theobald.
      Haematophagous mosquitoes need a blood meal to complete their reproductive cycle. To accomplish this, female mosquitoes seek vertebrate hosts, land on them and bite. As their eggs mature, they shift attention away from hosts and towards finding sites to lay eggs. We asked whether females were more tuned to visual cues when a host-related signal, carbon dioxide, was present, and further examined the effect of a blood meal, which shifts behaviour to ovipositing. Using a custom, tethered-flight arena that records wing stroke changes while displaying visual cues, we found the presence of carbon dioxide enhances visual attention towards discrete stimuli and improves contrast sensitivity for host-seeking Aedes aegypti mosquitoes. Conversely, intake of a blood meal reverses vertical bar tracking, a stimulus that non-fed females readily follow. This switch in behaviour suggests that having a blood meal modulates visual attention in mosquitoes, a phenomenon that has been described before in olfaction but not in visually driven behaviours.
    Keywords:  Aedes aegypti; insect flight; insect vision; optomotor responses
    DOI:  https://doi.org/10.1098/rsbl.2022.0270
  12. Parasit Vectors. 2022 Sep 29. 15(1): 346
    Global trends in research on the effects of climate change on Aedes aegypti: international collaboration has increased, but some critical countries lag behind.
    Ana Cláudia Piovezan-Borges, Francisco Valente-Neto, Gustavo Lima Urbieta, Susan G W Laurence, Fabio de Oliveira Roque.
      BACKGROUND: Mosquito-borne diseases (e.g., transmitted by Aedes aegypti) affect almost 700 million people each year and result in the deaths of more than 1 million people annually.METHODS: We examined research undertaken during the period 1951-2020 on the effects of temperature and climate change on Ae. aegypti, and also considered research location and between-country collaborations.
    RESULTS: The frequency of publications on the effects of climate change on Ae. aegypti increased over the period examined, and this topic received more attention than the effects of temperature alone on this species. The USA, UK, Australia, Brazil, and Argentina were the dominant research hubs, while other countries fell behind with respect to number of scientific publications and/or collaborations. The occurrence of Ae. aegypti and number of related dengue cases in the latter are very high, and climate change scenarios predict changes in the range expansion and/or occurrence of this species in these countries.
    CONCLUSIONS: We conclude that some of the countries at risk of expanding Ae. aegypti populations have poor research networks that need to be strengthened. A number of mechanisms can be considered for the improvement of international collaboration, representativity and diversity, such as research networks, internationalization programs, and programs that enhance representativity. These types of collaboration are considered important to expand the relevant knowledge of these countries and for the development of management strategies in response to climate change scenarios.
    Keywords:  Bibliometric analysis; International collaboration; Primary dengue virus vector; Temperature effects
    DOI:  https://doi.org/10.1186/s13071-022-05473-7
  13. Pan Afr Med J. 2022 ;41(Suppl 1): 5
    An outbreak of malaria caused by increase in malaria breeding sites in swamps.
    Steven Ndugwa Kabwama, Benon Kwesiga, Lilian Bulage, Daniel Kadobera, Alex Riolexus Ario, Julie Rebecca Harris.
      On 10th June 2019, routine analysis of malaria surveillance data at the National Malaria Control Division, Ministry of Health in Uganda revealed that there was an unusual increase in the number of malaria cases reported in the Oyam District. On 11th June 2019, the District Health Officer in Oyam District convened a meeting with the District Health Team (DHT) in which the District Biostatistician confirmed that the number of malaria cases had indeed exceeded the upper limit, starting in epidemic week 24 (approximately the week of June 10). The District Health Officer issued a formal request to the Ministry of Health for assistance in dealing with the malaria outbreak in Oyam. Two field epidemiology residents were assigned to work with the District Health Team to investigate the outbreak. The residents followed the steps in conducting vector borne disease outbreak investigations including preparation for field work, establishment of the existence of an outbreak by analyzing surveillance data, descriptive data analysis, hypothesis generation, conducting environmental and entomological assessments, conducting analytic studies with a focus on the utility of retrospective cohort studies as well as reporting findings. This case study teaches trainees in Field Epidemiology and Laboratory Training Programs, public health students, public health workers who are interested or who may participate in vector borne disease outbreak investigation and response.
    Keywords:  Case Study; Uganda; malaria; outbreak investigation; retrospective cohort
    DOI:  https://doi.org/10.11604/pamj.supp.2022.41.1.31258
  14. GeoJournal. 2022 Sep 16. 1-22
    Dengue risk zone mapping of Thiruvananthapuram district, India: a comparison of the AHP and F-AHP methods.
    G Harsha, T S Anish, A Rajaneesh, Megha K Prasad, Ronu Mathew, Pratheesh C Mammen, R S Ajin, Sekhar L Kuriakose.
      Dengue fever, which is spread by Aedes mosquitoes, has claimed many lives in Kerala, with the Thiruvananthapuram district bearing the brunt of the toll. This study aims to demarcate the dengue risk zones in Thiruvananthapuram district using the analytical hierarchy process (AHP) and the fuzzy-AHP (F-AHP) methods. For the risk modelling, geo-environmental factors (normalized difference vegetation index, land surface temperature, topographic wetness index, land use/land cover types, elevation, normalized difference built-up index) and demographic factors (household density, population density) have been utilized. The ArcGIS 10.8 and ERDAS Imagine 8.4 software tools have been used to derive the risk zone maps. The area of the risk maps is classified into five zones. The dengue risk zone maps were validated using dengue case data collected from the Integrated Disease Surveillance Programme portal. From the receiver operating characteristic (ROC) curve analysis and the area under the ROC curve (AUC) values, it is proved that the F-AHP method (AUC value of 0.971) has comparatively more prediction capability than the AHP method (AUC value of 0.954) in demarcating the dengue risk zones. Also, based on the comparison of the risk zone map with actual case data, it was confirmed that around 82.87% of the dengue cases occurred in the very high and high-risk zones, thus proving the efficacy of the model. According to the dengue risk map prepared using the F-AHP model, 9.09% of the area of Thiruvananthapuram district is categorized as very high risk. The prepared dengue risk maps will be helpful for decision-makers, staff with the health, and disaster management departments in adopting effective measures to prevent the risks of dengue spread and thereby minimize loss of life.
    Keywords:  Aedes mosquito; Analytical hierarchy process; Dengue outbreak; F-AHP; ROC
    DOI:  https://doi.org/10.1007/s10708-022-10757-7
  15. Pan Afr Med J. 2022 ;41(Suppl 1): 2
    You cannot find what you are not looking for! detecting malaria outbreaks in Uganda: a case study.
    Benon Kwesiga, Phoebe Nabunya, Alex Riolexus Ario, Daniel Kadobera, Lilian Bulage, Stephen Ndugwa Kabwama, Julie Roberts Harris.
      Malaria is the leading cause of morbidity and mortality in Uganda, with nearly half of the population becoming infected in any given year. Uganda relies on analyzing high-quality surveillance data to help detect outbreaks, determine which areas or population groups are most affected, and help target resources to where they are most needed. In March 2019, over 300 health facilities from different districts in Uganda reported substantially higher malaria cases than usual. In 13 districts, health facilities reported that the number of malaria cases was so high that they were experiencing stock outs of antimalarial drugs. Although seasonal increases in cases had been expected, districts reported that the number of cases being identified were overwhelming the capacity of the health facilities. Uganda´s National Malaria Control Division tasked a team of epidemiologists to investigate this unprecedented increase in malaria cases. National Malaria Control Division were interested in how malaria epidemiology had been changing in recent years, and whether they had missed something that would have predicted the situation they were facing in 2019. This case study describes the steps taken to conduct a descriptive analysis of routine malaria surveillance data and demonstrates how to detect malaria outbreaks using historical data. It is useful for training Field Epidemiologists and public health officers involved in analysis of surveillance data.
    Keywords:  Case-Study; Uganda; analysis; data; detection; malaria; outbreak; surveillance
    DOI:  https://doi.org/10.11604/pamj.supp.2022.41.1.31191
  16. Pan Afr Med J. 2021 ;40(Suppl 1): 3
    Malaria frontline project: pre-intervention Malaria baseline assessment in Kano and Zamfara States, August 2016.
    Adefisoye Oluwaseun Adewole, Shelby Cash, Amina Umar, Olufemi Ajumobi, Usaini Bala, Ndadilnasiya Waziri, Saheed Gidado, Ieren Isaac, Gideon Ugbenyo, Edwin Simple, Patrick Nguku, Anisa Saleh, Steve Yoon, Stephen Patrick Kachur, Kwame Asamoa.
      Introduction: In 2016, the Centers for Disease Control and Prevention and the Government of Nigeria initiated the Malaria Frontline Project in Kano and Zamfara States. The project goal is to improve the quality and coverages of malaria interventions adapting polio program strategy. We conducted a baseline assessment of malaria interventions.Methods: Twenty-four primary health centers per State were selected using probability sampling. Health workers (HW) were purposively sampled to assess their knowledge of national malaria control guidelines. Clients were selected for exit interview to assess health workers´ adherence to the national guidelines. WHO cluster methodology was used to survey heads of household and women of reproductive age on knowledge of malaria prevention, Long Lasting Insecticidal Net (LLIN) ownership and use.
    Results: Of the 158 HW interviewed, 94.3% knew the correct criteria for malaria diagnosis, 86.1% reported using artemisinin-based therapy to treat uncomplicated malaria. About 45% of HW reported prescribing artemisinin-based combination therapy (ACT) for uncomplicated malaria in first trimester of pregnancy and 39% prescribed quinine. Only 73.9% of fever cases were referred to laboratory as recommended by the national guideline. Households with one LLIN per 2 persons (Kano: 27.1%; Zamfara: 30.0%), LLIN use (Kano: 70.8%; Zamfara: 81.6%) and IPTp1 (Kano: 38.6%; Zamfara: 33.3%).
    Conclusion: most clinicians have knowledge of national guidelines, but fewer adhere to guidelines in practice. Population LLIN ownership, LLIN use among pregnant women and IPTp are lower than the national targets of 58%, 83% and 75% respectively for 2016. We recommend improving health workers´ technical capacity and adherence to national malaria guidelines.
    Keywords:  LLIN; Malaria; Nigeria; assessment; diagnosis; surveillance
    DOI:  https://doi.org/10.11604/pamj.supp.2021.40.1.18809
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