The impact of the expansion of urban vegetable farming on malaria transmission in major cities of Benin

Yadouléton, Anges; N’Guessan, Raphaël; Allagbé, H.; Asidi, Alex; Boko, Michel; Osse, Razack; Padonou, Germain Gil; Gazard, Kinde; Akogbéto, Martin

doi:10.1186/1756-3305-3-118

Cited by 51 publications

(51 citation statements)

References 19 publications

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“…gambiae s.s. population from areas with massive cotton production (Korhogo, Kaforo) displayed the highest resistance levels against almost all insecticides classes (organochlorides, pyrethroids and carbamates) as previously reported [34], [40]–[44]. Urban vegetable farming in Yopougon, Port-Bouët and Yamoussoukro areas was also associated with high levels of resistance, as previously detected [45]–[48]. The trend was not so clear within the rice-growing areas, generally associated with low application of insecticide [40], [44] but where moderate to high resistance level was found in An.gambiae [49].…”

Section: Discussionsupporting

confidence: 79%

Re-Visiting Insecticide Resistance Status in Anopheles gambiae from Côte d'Ivoire: A Nation-Wide Informative Survey

et al. 2013

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Insecticide resistance constitutes a major threat that may undermine current gain in malaria control in most endemic countries. National Malaria Control Programmes (NMCPs) need as much information as possible on the resistance status of malaria vectors and underlying mechanisms in order to implement the most relevant and efficient control strategy. Bioassays, biochemical and molecular analysis were performed on An. gambiae collected in six sentinel sites in Côte d'Ivoire. The sites were selected on the basis of their bioclimatic status and agricultural practices. An. gambiae populations across sites showed high levels of resistance to organochloride, pyrethroid and carbamate insecticides. The kdr and ace-1R mutations were detected in almost all sentinel sites with mosquitoes on the coastal and cotton growing areas mostly affected by these mutations. At almost all sites, the levels of detoxifying enzymes (mixed-function oxidases (MFOs), non-specific esterases (NSE) and glutathione-S-transferases (GSTs)) in An. gambiae populations were significantly higher than the levels found in the susceptible strain Kisumu. Pre-exposure of mosquitoes to PBO, an inhibitor of MFOs and NSEs, significantly increased mortality rates to pyrethroids and carbamates in mosquitoes but resistance in most cases was not fully synergised by PBO, inferring a residual role of additional mechanisms, including kdr and ace-1 site insensitivity. The large distribution of resistance in Côte d'Ivoire raises an important question of whether to continue to deploy pyrethroid-based long-lasting insecticidal nets (LLINs) and insecticide residual spraying (IRS) towards which resistance continues to rise with no guarantee that the level of resistance would not compromise their efficacy. Innovative strategies that combine insecticide and synergists in LLINs or spatially LLIN and an effective non-pyrethroid insecticide for IRS could be in the short term the best practice for the NMCP to manage insecticide resistance in malaria vectors in Côte d'Ivoire and other endemic countries facing resistance.

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Section: Discussionsupporting

confidence: 79%

Re-Visiting Insecticide Resistance Status in Anopheles gambiae from Côte d'Ivoire: A Nation-Wide Informative Survey

et al. 2013

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“…Furthermore, unplanned settlements are typically built upon less desirable land, and often in proximity to existing natural breeding sites such as swamps or other hydrological networks associated with increased malaria risk [11,13,[16][17][18][19]. Finally, agricultural activities, with their associated irrigation systems, can provide breeding sites and, therefore, increase malaria transmission in urban and peri-urban areas [19][20][21][22][23]. The spatial heterogeneity of these factors in urban areas leads to huge variation in the entomological inoculation rate (EIR) both across and within urban cities throughout malaria endemic regions.…”

Section: Introductionmentioning

confidence: 99%

The use of spatial and genetic tools to assess Plasmodium falciparum transmission in Lusaka, Zambia between 2011 and 2015

Bridges

Chishimba

Mwenda

et al. 2020

Malar J

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Background: Zambia has set itself the ambitious target of eliminating malaria by 2021. To continue tracking transmission to zero, new interventions, tools and approaches are required. Methods: Urban reactive case detection (RCD) was performed in Lusaka city from 2011 to 2015 to better understand the location and drivers of malaria transmission. Briefly, index cases were followed to their home and all consenting individuals living in the index house and nine proximal houses were tested with a malaria rapid diagnostic test and treated if positive. A brief survey was performed and for certain responses, a dried blood spot sample collected for genetic analysis. Aggregate health facility data, individual RCD response data and genetic results were analysed spatially and against environmental correlates. Results: Total number of malaria cases remained relatively constant, while the average age of incident cases and the proportion of incident cases reporting recent travel both increased. The estimated R 0 in Lusaka was < 1 throughout the study period. RCD responses performed within 250 m of uninhabited/vacant land were associated with a higher probability of identifying additional infections. Conclusions: Evidence suggests that the majority of malaria infections are imported from outside Lusaka. However there remains some level of local transmission occurring on the periphery of urban settlements, namely in the wet season. Unfortunately, due to the higher-than-expected complexity of infections and the small number of samples tested, genetic analysis was unable to identify any meaningful trends in the data.

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“…Therefore, it is concerning that most national malaria control programmes (NMCPs) continue to use pyrethroid insecticides for vector control. The situation is also compounded by the extensive use of pyrethroids in agriculture, which poses an additional selection pressure on malaria vectors, for example via insecticide-contaminated ground water that permeates to mosquito larval habitats [14, 16, 17]. …”

Section: Introductionmentioning

confidence: 99%

Susceptibility of Anopheles gambiae to insecticides used for malaria vector control in Rwanda

Hakizimana

Karema

Munyakanage

et al. 2016

Malar J

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BackgroundThe widespread emergence of resistance to pyrethroids is a major threat to the gains made in malaria control. To monitor the presence and possible emergence of resistance against a variety of insecticides used for malaria control in Rwanda, nationwide insecticide resistance surveys were conducted in 2011 and 2013.MethodsLarvae of Anopheles gambiae sensu lato mosquitoes were collected in 12 sentinel sites throughout Rwanda. These were reared to adults and analysed for knock-down and mortality using WHO insecticide test papers with standard diagnostic doses of the recommended insecticides. A sub-sample of tested specimens was analysed for the presence of knockdown resistance (kdr) mutations.ResultsA total of 14,311 mosquitoes were tested and from a sample of 1406 specimens, 1165 (82.9%) were identified as Anopheles arabiensis and 241 (17.1%) as Anopheles gambiae sensu stricto. Mortality results indicated a significant increase in resistance to lambda-cyhalothrin from 2011 to 2013 in 83% of the sites, permethrin in 25% of the sites, deltamethrin in 25% of the sites and DDT in 50% of the sites. Mosquitoes from 83% of the sites showed full susceptibility to bendiocarb and 17% of sites were suspected to harbour resistance that requires further confirmation. No resistance was observed to fenitrothion in all study sites during the entire survey. The kdr genotype results in An. gambiae s.s. showed that 67 (50%) possessed susceptibility (SS) alleles, while 35 (26.1%) and 32 (23.9%) mosquitoes had heterozygous (RS) and homozygous (RR) alleles, respectively. Of the 591 An. arabiensis genotyped, 425 (71.9%) possessed homozygous (SS) alleles while 158 (26.7%) and 8 (1.4%) had heterozygous (RS) and homozygous (RR) alleles, respectively. Metabolic resistance involving oxidase enzymes was also detected using the synergist PBO.ConclusionThis is the first nationwide study of insecticide resistance in malaria vectors in Rwanda. It shows the gradual increase of insecticide resistance to pyrethroids (lambda-cyhalothrin, deltamethrin, permethrin) and organochlorines (DDT) and the large presence of target site insensitivity. The results demonstrate the need for Rwanda to expand monitoring for insecticide resistance including further metabolic resistance testing and implement an insecticide resistance management strategy to sustain the gains made in malaria control.

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The impact of the expansion of urban vegetable farming on malaria transmission in major cities of Benin

Cited by 51 publications

References 19 publications

Re-Visiting Insecticide Resistance Status in Anopheles gambiae from Côte d'Ivoire: A Nation-Wide Informative Survey

Re-Visiting Insecticide Resistance Status in Anopheles gambiae from Côte d'Ivoire: A Nation-Wide Informative Survey

The use of spatial and genetic tools to assess Plasmodium falciparum transmission in Lusaka, Zambia between 2011 and 2015

Susceptibility of Anopheles gambiae to insecticides used for malaria vector control in Rwanda

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