Impact of long-lasting insecticidal nets on prevalence of subclinical malaria among children in the presence of pyrethroid resistance in Anopheles culicifacies in Central India

Abstract Background The success of malaria control using long-lasting insecticidal nets (LLINs) is threatened by pyrethroid resistance developed by the malaria vectors, worldwide. To combat the resistance, synergist piperonyl butoxide (PBO) incorporated LLINs is one of the available options. In the current phase II hut trial, the efficacy of Veeralin®LN (an alpha-cypermethrin and PBO-incorporated net) was evaluated against Anopheles culicifacies, a pyrethroid resistant malaria vector. Methods The performance of Veeralin®LN was compared with MAGNet®LN and untreated net in reducing the entry, induced exit, mortality and blood feeding inhibition of target vector species. Results The performance of Veeralin was equal to MAGNet in terms of reducing hut entry, inhibiting blood feeding and inducing exophily, and with regard to causing mortality Veeralin was better than MAGNet. When compared to untreated net, a significant reduction in hut entry and blood feeding and an increase in exophily and mortality were observed with Veeralin. In cone bioassays, unwashed Veeralin caused > 80% mortality of An. culicifacies. Conclusions Veeralin performed equal to (entry, exit, feeding) or better than (mortality in huts and cone bioassays) MAGNet and could be an effective tool against pyrethroid resistant malaria vectors.

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Escalation of Pyrethroid Resistance in the Malaria Vector Anopheles funestus Induces a Loss of Efficacy of Piperonyl Butoxide–Based Insecticide-Treated Nets in Mozambique

The Journal of Infectious Diseases ◽

10.1093/infdis/jiz139 ◽

2019 ◽

Vol 220 (3) ◽

pp. 467-475 ◽

Cited By ~ 16

Author(s):

Jacob M Riveron ◽

Silvie Huijben ◽

Williams Tchapga ◽

Magellan Tchouakui ◽

Murielle J Wondji ◽

...

Keyword(s):

Cytochrome P450 ◽

Pyrethroid Resistance ◽

Anopheles Funestus ◽

Resistance Mechanisms ◽

Piperonyl Butoxide ◽

Insecticide Treated Nets ◽

Molecular Analyses ◽

Cytochrome P450 Genes ◽

High Degree ◽

Long Lasting Insecticidal Nets

Abstract Background Insecticide resistance poses a serious threat to insecticide-based interventions in Africa. There is a fear that resistance escalation could jeopardize malaria control efforts. Monitoring of cases of aggravation of resistance intensity and its impact on the efficacy of control tools is crucial to predict consequences of resistance. Methods The resistance levels of an Anopheles funestus population from Palmeira, southern Mozambique, were characterized and their impact on the efficacy of various insecticide-treated nets established. Results A dramatic loss of efficacy of all long-lasting insecticidal nets (LLINs), including piperonyl butoxide (PBO)–based nets (Olyset Plus), was observed. This An. funestus population consistently (2016, 2017, and 2018) exhibited a high degree of pyrethroid resistance. Molecular analyses revealed that this resistance escalation was associated with a massive overexpression of the duplicated cytochrome P450 genes CYP6P9a and CYP6P9b, and also the fixation of the resistance CYP6P9a_R allele in this population in 2016 (100%) in contrast to 2002 (5%). However, the low recovery of susceptibility after PBO synergist assay suggests that other resistance mechanisms could be involved. Conclusions The loss of efficacy of pyrethroid-based LLINs with and without PBO is a concern for the effectiveness of insecticide-based interventions, and action should be taken to prevent the spread of such super-resistance.

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Assessing the impact of low-technology emanators alongside long-lasting insecticidal nets to control malaria

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0817 ◽

2020 ◽

Vol 376 (1818) ◽

pp. 20190817 ◽

Cited By ~ 1

Author(s):

Joel Hellewell ◽

Ellie Sherrard-Smith ◽

Sheila Ogoma ◽

Thomas S. Churcher

Keyword(s):

Disease Transmission ◽

Pyrethroid Resistance ◽

Control Strategies ◽

Indoor Residual Spraying ◽

Additional Benefit ◽

Sub Saharan Africa ◽

Outdoor Biting ◽

Mosquito Mortality ◽

The Impact ◽

Long Lasting Insecticidal Nets

Malaria control in sub-Saharan Africa relies on the widespread use of long-lasting insecticidal nets (LLINs) or the indoor residual spraying of insecticide. Disease transmission may be maintained even when these indoor interventions are universally used as some mosquitoes will bite in the early morning and evening when people are outside. As countries seek to eliminate malaria, they can target outdoor biting using new vector control tools such as spatial repellent emanators, which emit airborne insecticide to form a protective area around the user. Field data are used to incorporate a low-technology emanator into a mathematical model of malaria transmission to predict its public health impact across a range of scenarios. Targeting outdoor biting by repeatedly distributing emanators alongside LLINs increases the chance of elimination, but the additional benefit depends on the level of anthropophagy in the local mosquito population, emanator effectiveness and the pre-intervention proportion of mosquitoes biting outdoors. High proportions of pyrethroid-resistant mosquitoes diminish LLIN impact because of reduced mosquito mortality. When mosquitoes are highly anthropophagic, this reduced mortality leads to more outdoor biting and a reduced additional benefit of emanators, even if emanators are assumed to retain their effectiveness in the presence of pyrethroid resistance. Different target product profiles are examined, which show the extra epidemiological benefits of spatial repellents that induce mosquito mortality. This article is part of the theme issue ‘Novel control strategies for mosquito-borne diseases’.

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Multiple insecticide resistance in Anopheles culicifacies s.l. (Diptera: Culicidae) in east-central India

Pathogens and Global Health ◽

10.1080/20477724.2019.1707398 ◽

2019 ◽

Vol 113 (8) ◽

pp. 352-358 ◽

Cited By ~ 2

Author(s):

Sudhansu Sekhar Sahu ◽

Sonia Thankachy ◽

Smrutidhara Dash ◽

Subramanian Swaminathan ◽

Gunasekaran Kasinathan ◽

...

Keyword(s):

Insecticide Resistance ◽

Central India ◽

Anopheles Culicifacies ◽

East Central

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Intensity of pyrethroid resistance in Anopheles culicifacies s.l. (Diptera: Culicidae) in Odisha State, India

Pathogens and Global Health ◽

10.1080/20477724.2020.1751999 ◽

2020 ◽

Vol 114 (4) ◽

pp. 205-211 ◽

Cited By ~ 1

Author(s):

Sudhansu Sekhar Sahu ◽

Sonia Thankachy ◽

Smrutidhara Dash ◽

Gunasekaran Kasinathan ◽

Ashwani Kumar

Keyword(s):

Pyrethroid Resistance ◽

Anopheles Culicifacies

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Influence of moonlight on light-trap catches of the malaria vector Anopheles culicifacies (Diptera: Culicidae) in central India

Bulletin of Entomological Research ◽

10.1017/s0007485300035057 ◽

1996 ◽

Vol 86 (4) ◽

pp. 475-479 ◽

Cited By ~ 8

Author(s):

Neeru Singh A.K. Mishra ◽

C.F. Curtis ◽

V.P. Sharma

Keyword(s):

Longitudinal Study ◽

Malaria Vector ◽

Light Trap ◽

Central India ◽

Moon Phase ◽

Total Catch ◽

Anopheles Culicifacies ◽

Tribal People ◽

Parity Rate ◽

Trap Catches

AbstractA significant effect of moon phase on light-trap catches of Anopheles species was observed during a longitudinal study carried out in a forested belt of Madhya Pradesh, India, inhabited by tribal people. However, moon phase does not seem to have any effect on the proportion of adult Anopheles culicifacies Giles in the total catch, or the parity rate in this species, which is the vector responsible for perennial transmission of malaria in the area.

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