scholarly journals The influence of feeding behaviour and temperature on the capacity of mosquitoes to transmit malaria

2019 ◽  
Author(s):  
Eunho Suh ◽  
Marissa K. Grossman ◽  
Jessica L. Waite ◽  
Nina L. Dennington ◽  
Ellie Sherrard-Smith ◽  
...  
Keyword(s):  
Feeding Behaviour ◽  
Vector Competence ◽  
Thermal Sensitivity ◽  
Blood Feeding ◽  
Malaria Vectors ◽  
Parasite Development ◽  
Bed Nets ◽  
Behavioural Resistance ◽  
Epidemiological Impact ◽  
Insecticide Treated Bed Nets

AbstractInsecticide-treated bed nets reduce malaria transmission by limiting contact between mosquito vectors and human hosts when mosquitoes feed during the night. However, malaria vectors can also feed in the early evening and in the morning when people are not protected. Here, we explored how timing of blood feeding interacts with environmental temperature to influence the capacity of Anopheles mosquitoes to transmit the human malaria parasite, Plasmodium falciparum. We found no effect of biting time itself on the proportion of mosquitoes that became infectious (vector competence) at constant temperature. However, when mosquitoes were maintained under more realistic fluctuating temperatures there was a significant increase in competence for mosquitoes feeding in the evening, and a significant reduction in competence for those feeding in the morning, relative to those feeding at midnight. These effects appear to be due to thermal sensitivity of malaria parasites during the initial stages of parasite development within the mosquito, and the fact that mosquitoes feeding in the evening experience cooling temperatures during the night, whereas mosquitoes feeding in the morning quickly experience warming temperatures that are inhibitory to parasite establishment. A transmission dynamics model illustrates that such differences in competence could have important implications for disease endemicity, the extent of transmission that persists in the presence of bed nets, and the epidemiological impact of behavioural resistance. These results indicate the interaction of temperature and feeding behaviour to be a major ecological determinant of the vectorial capacity of malaria mosquitoes.

scholarly journals An Experimental Hut Evaluation of PBO-Based and Pyrethroid-Only Nets against the Malaria Vector Anopheles funestus Reveals a Loss of Bed Nets Efficacy Associated with GSTe2 Metabolic Resistance

Genes ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 143 ◽  
Author(s):  
Benjamin D. Menze ◽  
Mersimine F. Kouamo ◽  
Murielle J. Wondji ◽  
Williams Tchapga ◽  
Micareme Tchoupo ◽  
...  
Keyword(s):  
Anopheles Funestus ◽  
Blood Feeding ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Glutathione S Transferase ◽  
Metabolic Resistance ◽  
Experimental Hut ◽  
The Impact ◽  
Long Lasting Insecticidal Nets ◽  
Permanet 3.0

Growing insecticide resistance in malaria vectors is threatening the effectiveness of insecticide-based interventions, including Long Lasting Insecticidal Nets (LLINs). However, the impact of metabolic resistance on the effectiveness of these tools remains poorly characterized. Using experimental hut trials and genotyping of a glutathione S-transferase resistance marker (L119F-GSTe2), we established that GST-mediated resistance is reducing the efficacy of LLINs against Anopheles funestus. Hut trials performed in Cameroon revealed that Piperonyl butoxide (PBO)-based nets induced a significantly higher mortality against pyrethroid resistant An. funestus than pyrethroid-only nets. Blood feeding rate and deterrence were significantly higher in all LLINs than control. Genotyping the L119F-GSTe2 mutation revealed that, for permethrin-based nets, 119F-GSTe2 resistant mosquitoes have a greater ability to blood feed than susceptible while the opposite effect is observed for deltamethrin-based nets. For Olyset Plus, a significant association with exophily was observed in resistant mosquitoes (OR = 11.7; p < 0.01). Furthermore, GSTe2-resistant mosquitoes (cone assays) significantly survived with PermaNet 2.0 (OR = 2.1; p < 0.01) and PermaNet 3.0 (side) (OR = 30.1; p < 0.001) but not for Olyset Plus. This study shows that the efficacy of PBO-based nets (e.g., blood feeding inhibition) against pyrethroid resistant malaria vectors could be impacted by other mechanisms including GST-mediated metabolic resistance not affected by the synergistic action of PBO. Mosaic LLINs incorporating a GST inhibitor (diethyl maleate) could help improve their efficacy in areas of GST-mediated resistance.

scholarly journals Intensity and mechanisms of deltamethrin and permethrin resistance in Anopheles gambiae s.l. populations in southern Benin

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Hermann Watson Sagbohan ◽  
Casimir D. Kpanou ◽  
Razaki Osse ◽  
Fortuné Dagnon ◽  
Germain G. Padonou ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Detoxification Enzymes ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Resistance Allele ◽  
Resistance Mutations ◽  
The Difference ◽  
Study Sites ◽  
Insecticide Treated Bed Nets ◽  
Southern Benin

Abstract Background Insecticide resistance is threatening the effectiveness of efforts to control malaria vectors in Benin. This study explores the levels and mechanisms of insecticide resistance in An. gambiae s.l. to pyrethroids. Methods Larvae were collected from August 2017 to July 2018 in five communes in southern Benin (Adjohoun, Allada, Bohicon, Cotonou, and Porto-Novo) representing diverse ecological regions, and were reared in Benin’s insectary. Two- to five-day-old female mosquitoes from each district were exposed to multiple doses of deltamethrin and permethrin (1×, 2×, 5×, and 10×) using the WHO insecticide resistance intensity bioassay. The effect of pre-exposure to the synergist, piperonyl butoxide (PBO), was also tested at different pyrethroid doses. Molecular allele frequencies of kdr (1014F) and ace-1R (119S) insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled from each study area. Results An. gambiae s.l. were resistant to pyrethroid-only exposure up to 10× the diagnostic doses in all the study sites for both deltamethrin and permethrin. Mortality was significantly higher in An. gambiae s.l. pre-exposed to PBO followed by exposure to deltamethrin or permethrin compared to mosquitoes exposed to deltamethrin or permethrin only (p < 0.001). The difference in mortality between deltamethrin only and PBO plus deltamethrin was the smallest in Cotonou (16–64%) and the greatest in Bohicon (12–93%). The mortality difference between permethrin only and PBO plus permethrin was the smallest in Cotonou (44–75%) and the greatest in Bohicon (22–72%). In all the study sites, the kdr resistance allele (1014F) frequency was high (75–100%), while the ace-1 resistance allele (G119S) frequency was low (0–3%). Analysis of the metabolic enzymatic activity of An. gambiae s.l. showed overexpression of nonspecific esterases and glutathione S-transferases (GST) in all study sites. In contrast to the PBO results, oxidase expression was low and was similar to the susceptible An. gambiae s.s. Kisumu strain in all sites. Conclusion There is high-intensity resistance to pyrethroids in southern Benin. However, pre-exposure to PBO significantly increased susceptibility to the pyrethroids in the different An. gambiae s.l. populations sampled. The use of PBO insecticide-treated bed nets may help maintain the gains in An. gambiae (s.l.) control in southern Benin. Graphical Abstract

scholarly journals Host-feeding Preference of Anopheles Species under Prolonged Use of Insecticide-treated Bed Nets in Kamuli District, Uganda: Implications for Vector Control

2020 ◽  
pp. 16-25
Author(s):  
Fredrick G. Kabbale ◽  
Anne M. Akol ◽  
John B. Kaddu ◽  
Enock Matovu ◽  
Anne Kazibwe ◽  
...  
Keyword(s):  
Vector Control ◽  
Blood Meal ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Enzyme Linked Immunosorbent Assay ◽  
Host Feeding ◽  
Bed Net ◽  
Insecticide Treated Bed Nets ◽  
Intervention Zone ◽  
Blood Meals

Background: The blood-feeding patterns are crucial in incriminating disease vectors as well as facilitating the design and consolidation of effective vector control interventions in an area.  Objective: This study aimed to establish if prolonged use of insecticide-treated bed nets (ITNs) caused a shift in the preferred hosts of the common malaria vectors as the hosts were under the bed net. Such a shift would render ITNs less effective and would probably explain the continued morbidity and mortality due to malaria in the highly endemic Kamuli district. Methods: A total of 3,519 indoor and outdoor human biting female Anopheles gambiae sensu lato and An. funestus mosquitoes were collected from 48 households using human-baited bed net traps. All 187 indoor resting blood-fed anophelines collected were tested by direct enzyme-linked immunosorbent assay (ELISA) for blood meal host identification. Of these, 73 mid guts came from 24 households in villages with a 69% ITNs coverage, while 114 mid guts were from 24 households in non-ITN villages. Results: Blood meal hosts were identified in only 10.96% (n = 8) and 14.91% (n = 17) of the Anopheles blood meals from the intervention and non-intervention zones, respectively. Other blood meals could not be clearly identified.  Eight (100%) blood meals in the intervention zone were from humans, while in the non-intervention zone, 15 (88.24%), one (5.88%) and one (5.88%) came from humans, cattle and goat, respectively. These findings demonstrated that the malaria vectors in Kamuli district are anthropophilic, with nearly all the mosquitoes collected from both zones feeding on humans during every blood meal (p = 0.82). This indicated high vector-human contacts, and thus implicating these species as important in the transmission of Plasmodium species and probably other infections. Conclusion: The use of insecticide-treated bed nets is effective for controlling malaria vectors inside houses, evoking universal coverage of houses in the area.

scholarly journals Preventive Measures Against The Vectors Of Malaria In Akanda, Southwest Gabon: Knowledge, Attitudes, Practices, And Beliefs

2021 ◽  
Vol 17 (21) ◽  
pp. 169
Author(s):  
Richard Pamba ◽  
Silas Lendzele Sevidzem ◽  
Aubin Armel Koumba ◽  
Christophe Roland Zinga-Koumba ◽  
Audrey Prisca Melodie Ovono ◽  
...  
Keyword(s):  
Preventive Measures ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Literacy Rate ◽  
Beliefs And Practices ◽  
Age Cohorts ◽  
Insecticide Treated Bed Nets

Background: Reliable data on the Knowledge, Attitudes, Beliefs, and Practices (KABP) of the indigenes of Akanda and its environs on the different approaches to fight against vectors of malaria is lacking. Objective: To evaluate the KABP of the indigenes of Akanda and its environs on the different techniques used to fight against vectors of malaria. Materials and Methods: A cross sectional survey using semi-structured questionnaires was conducted on heads of randomly selected households at Akanda from April to June 2019. Results: We interviewed 369 heads of households and the population had a high literacy rate. It was noticed that 94% of respondents knew that mosquitoes could transmit malaria. More than 80% believed that Insecticide-Treated bed Nets (ITNs) could protect them from malaria infection. There was no preference in ITNs usage with age cohorts and seasons of the year. The ITNs owned by respondents were mostly purchased from shops. Respondents underlined that their reluctance to sleep under ITNs was because of their inability to breath under such conditions. Also, apart from the use of ITNs for malaria control, Indoor Residual Spraying (IRS) using insecticides (mostly Rambo®) purchased from shops and cleaning around house surroundings were practiced by >50% of respondents. Conclusion: Despite respondent’s awareness of mosquitoes as vectors of malaria as well as the use of ITNs, IRS, and cleaning of home surroundings to reduce malaria vectors burden, the ITNs coverage rate is very weak and more sensitization is also required at Akanda in Gabon.

scholarly journals Activity of Cytochrome P450 Monooxygenase (CYPs) Metabolic Enzymes as Markers of Insecticide Resistance in Anopheles vagus Muara Enim Mosquitoes, Indonesia

2021 ◽  
Vol 5 (2) ◽  
pp. 305-311
Author(s):  
Dalilah ◽  
Muhaimin Ramdja ◽  
Dwi Handayani ◽  
Lasbudi P Ambarita ◽  
R. Irpan Pahlepi ◽  
...  
Keyword(s):  
Biochemical Test ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Synthetic Pyrethroids ◽  
Elisa Method ◽  
P450 Monooxygenase ◽  
Collection Method ◽  
Anopheles Mosquitoes ◽  
Insecticide Treated Bed Nets ◽  
Anopheles Vagus

A B S T R A C TThe use of synthetic pyrethroids in insecticide-treated bed nets (LLINs) and sprayform (IRS) has been carried out since 2012 in Muara Emil Village and since 2016 inall villages in Tanjung Agung District, Muara Enim Regency. Biochemical resistancecan occur to the enzymes that play a role in detoxifying the insecticide. This studyaims to identify whether there is an increase in the levels of the enzyme CytochromeP450 monooxygenase (CYPs) through the enzyme biochemical test on the malariavector mosquito Anopheles vagus originating from Pagar Dewa Village and MuaraEmil Village, Muara Enim Regency. The sample of female Anopheles mosquitoes wasnot full. Blood was taken at night using the resting collection method. Mosquitoesthat have been identified as Anopheles vagus species are used to check CYPs enzymelevels using the ELISA method. The results of the biochemical test showed thatenzyme levels increased from the Muara emil and Pagar Dewa village mosquitoeswith a percentage of 71% and 61.53% (with cut off point OD> 0.165). The value ofCYPs enzyme levels for mosquitoes from Muara Emil village was higher than that ofthe mosquitoes from Pagar Dewa Village (mean 0.005027 ± 0.007). The increasedactivity of the CYPs enzyme plays a role in the detoxification of synthetic pyrethroidinsecticides that can cause resistance. The high levels of enzymes from the villagesof Muara Emil and Desa Farah Dewa are in line with intensive insecticide exposurein eradicating malaria vectors in the highest malaria transmission areas in MuaraEnim Regency.

scholarly journals The diversity of Anopheles blood feeding patterns suggests different malaria protection strategies in different localities

F1000Research ◽  
2020 ◽  
Vol 8 ◽  
pp. 1217
Author(s):  
Irfanul Chakim ◽  
Tepanata Pumpaibool
Keyword(s):  
Blood Feeding ◽  
Biological Properties ◽  
Bed Nets ◽  
Feeding Patterns ◽  
Protection Strategy ◽  
Health Report ◽  
Protection Strategies ◽  
Vector Activity ◽  
Insecticide Treated Bed Nets ◽  
Malaria Protection

Background: Malaria is a significant health burden for many countries worldwide. Insecticide-treated bed nets and mosquito repellent are considered effective methods for preventing Anopheles bites. However, changes in the biological properties of the vector have led to a reduction in their effectiveness. Most published studies have only investigated the human population factor, not the dynamics of vector behavior. Therefore, this study aims to investigate the importance of primary vector activity for selecting an appropriate malaria protection strategy. Methods: Initially, active case detection (ACD) was carried out in western and eastern parts of Indonesia, Jambi and Sumba, to confirm their endemicity level. According to the 2016 national health report of Indonesia, Jambi has an annual parasite index (API) of 0.14 and Sumba has an API of 5.41. A series of entomological observations were carried out to compare the biting activity of Anopheles vectors in two localities, with a total of 216 houses and 216 catchers (108 at each study site). Results: The results indicated that endemicity at the sub-district level is higher than that at the provincial level. Only Anopheles balabacensi was found to be exophagic. Multiple comparisons found different biting times between the sites, suggesting that early evening (18.00-20.00) is most likely to be the time when mosquitoes transmit the Plasmodium parasite in Jambi, while during sleeping hours (21.00-01.00) is the peak biting time of Anopheles mosquitoes in Sumba. Conclusions: The study demonstrates the importance of Anopheles species blood feeding patterns in selecting an appropriate malaria protection strategy.

scholarly journals A Systematic Review: Is Aedes albopictus an Efficient Bridge Vector for Zoonotic Arboviruses?

Pathogens ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 266 ◽  
Author(s):  
Taissa Pereira-dos-Santos ◽  
David Roiz ◽  
Ricardo Lourenço-de-Oliveira ◽  
Christophe Paupy
Keyword(s):  
Aedes Albopictus ◽  
Feeding Behaviour ◽  
Vector Competence ◽  
Blood Feeding ◽  
Natural Ecosystems ◽  
Human Disturbances ◽  
Breeding Sites ◽  
Bibliographic Search ◽  
Natural Settings ◽  
Mosquito Communities

Mosquito-borne arboviruses are increasing due to human disturbances of natural ecosystems and globalization of trade and travel. These anthropic changes may affect mosquito communities by modulating ecological traits that influence the “spill-over” dynamics of zoonotic pathogens, especially at the interface between natural and human environments. Particularly, the global invasion of Aedes albopictus is observed not only across urban and peri-urban settings, but also in newly invaded areas in natural settings. This could foster the interaction of Ae. albopictus with wildlife, including local reservoirs of enzootic arboviruses, with implications for the potential zoonotic transfer of pathogens. To evaluate the potential of Ae. albopictus as a bridge vector of arboviruses between wildlife and humans, we performed a bibliographic search and analysis focusing on three components: (1) The capacity of Ae. albopictus to exploit natural larval breeding sites, (2) the blood-feeding behaviour of Ae. albopictus, and (3) Ae. albopictus’ vector competence for arboviruses. Our analysis confirms the potential of Ae. albopictus as a bridge vector based on its colonization of natural breeding sites in newly invaded areas, its opportunistic feeding behaviour together with the preference for human blood, and the competence to transmit 14 arboviruses.

scholarly journals Pengendalian Vektor Malaria di Daerah Endemis Kabupaten Purworejo, Indonesia

2018 ◽  
pp. 1-12
Author(s):  
Riyani Setiyaningsih ◽  
Wiwik Trapsilowati ◽  
Mujiyono Mujiyono ◽  
Lasmiati Lasmiati
Keyword(s):  
Vector Control ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Bed Nets ◽  
Control Methods ◽  
Mosquito Nets ◽  
Bioassay Test ◽  
Insecticide Treated Bed Nets ◽  
And Control ◽  
Breeding Place

Purworejo is the endemic area of ​​malaria with the highest case increase occurring in 2015 amounted to 1411 cases. Appropriate control can be performed effectively based on vector bionomics. The aims of study were to determine species, behavior, resistance, and control methods of malaria vectors. Methods were larva andmosquitoes collection, breeding place of mosquitoes surveys, resistance of mosquito and evaluation of the effectiveness of vector control. The research was conducted in Sendangsari Village, Bener District, Purworejo Regency The result of the research showed that An. barbirostris sucked blood indoor, outdoor, and cage. An. balabacensis sucked blood indoor and cage. An. maculatus, An. aconitus, An. kochi, An. Indifinitus, and An. fagus were found to suck blood in the cage. An. maculatus showed resistance to insecticide permetrin 0,75% Indoor Residual spraying (IRS) and the use of insecticide treated bed nets were the vector control perfomed in the area of study. The breeding place of mosquito were in hole around unused fields and pond. Based on bioassay test, the effectiveness of IRS application for one months were not effectively kill An. maculatus while the use of mosquito nets for three months were still effectively kill An. maculatus.

scholarly journals Adaptive periodicity in the infectivity of malaria gametocytes to mosquitoes

2018 ◽  
Author(s):  
Petra Schneider ◽  
Samuel S. C. Rund ◽  
Natasha L. Smith ◽  
Kimberley F. Prior ◽  
Aidan J. O’Donnell ◽  
...  
Keyword(s):  
Blood Feeding ◽  
Blood Parasite ◽  
Parasite Development ◽  
Bed Nets ◽  
Mosquito Vectors ◽  
Plasmodium Chabaudi ◽  
Malaria Parasites ◽  
Rodent Malaria

AbstractThat periodicity in the biting activity of mosquito vectors explains why malaria parasites have evolved rhythms in cycles of asexual replication in the host’s blood was proposed almost 50 years ago. Yet, tests of this hypothesis have proved inconclusive. Using the rodent malaria Plasmodium chabaudi, we examine rhythms in the density and infectivity of transmission forms (gametocytes) in the host’s blood, parasite development inside mosquitoes, and onwards transmission.Moreover, we control for the confounding effects of rhythms in mosquito susceptibility. We reveal that at night, gametocytes are twice as infective to mosquitoes, despite being less numerous in the blood. This enhanced infectiousness at night interacts with mosquito rhythms to increase sporozoite burdens by almost four-fold when mosquitoes feed during their day. Thus, daytime blood-feeding (e.g. driven by the use of bed nets) may render gametocytes less infective, but this is compensated for by the greater susceptibility of mosquitoes.

scholarly journals The diversity of Anopheles blood feeding patterns suggests different malaria protection strategies in different localities

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1217 ◽  
Author(s):  
Irfanul Chakim ◽  
Tepanata Pumpaibool
Keyword(s):  
Blood Feeding ◽  
Biological Properties ◽  
Bed Nets ◽  
Feeding Patterns ◽  
Protection Strategy ◽  
Health Report ◽  
Protection Strategies ◽  
Vector Activity ◽  
Insecticide Treated Bed Nets ◽  
Malaria Protection

Background: Malaria is a significant health burden for many countries worldwide. Insecticide-treated bed nets and mosquito repellent are considered effective methods for preventing Anopheles bites. However, changes in the biological properties of the vector have led to a reduction in their effectiveness. Most published studies have only investigated the human population factor, not the dynamics of vector behavior. Therefore, this study aims to investigate the importance of primary vector activity for selecting an appropriate malaria protection strategy. Methods: Initially, active case detection (ACD) was carried out in western and eastern parts of Indonesia, Jambi and Sumba, to confirm their endemicity level. According to the 2016 national health report of Indonesia, Jambi has an annual parasite index (API) of 0.14 and Sumba has an API of 5.41. A series of entomological observations were carried out to compare the biting activity of Anopheles vector in two localities, with a total of 216 houses and catchers (108 in each study site). Results: The results indicated that endemicity at the sub-district level is higher than that at the provincial level. Only Anopheles balabacensi was found to be exophagic. Multiple comparisons found different biting times between the sites, suggesting that early evening (18.00-20.00) is most likely to be the time when mosquitos transmit the Plasmodium parasite in Jambi, while during sleeping hours (21.00-01.00) is the peak biting time of Anopheles mosquitos in Sumba. Conclusions: The study demonstrates the importance of Anopheles species blood feeding patterns in selecting an appropriate malaria protection strategy.

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