CONTRIBUTION FROM READER

Thanks to Helen Pates Jamet, of Vestergaard-Fransen, who points out three open source publications looking at the performance of Vestergaard products.

Abstracts and weblinks follow.

Contributions from other readers on this topic would be most welcome.

Good reading.

BD

Dear Robert,

Please find below a very brief summary of each of the open source items

 1.      Van Bortel et al (2009) Impact of insecticide-treated nets on wild pyrethroid resistant Anopheles epiroticus population from southern Vietnam tested in experimental huts. Malaria J, 8, 248.

• ·         This study showed that PermaNet® 3.0 meets WHO Phase 2 criteria for an LLIN and that insecticide resistance in An. epiroticus as defined by the WHO susceptibility test is not yet having an impact on the performance of the LLINs tested in this study.

2.       Tungu et al, (2010) Evaluation of PermaNet 3.0 a deltamethrin-PBO combination net against Anopheles gambiae and pyrethroid resistant Culex quinquefasciatus mosquitoes: an experimental hut trial in Tanzania. Malaria J, 9, 21.

• ·         This study showed that PermaNet 3.0 performed according to current WHOPES guidelines and fulfilled the criteria of an LLIN. This study does not provide evidence of increased bioefficacy against pyrethroid-resistant malaria vectors because the vectors in the study area were susceptible. No conclusions can be drawn from the Culex data because of the extremely low numbers caught throughout the study.

3.      Corbel et al (2010) Field efficacy of a new mosaic long-lasting mosquito net (PermaNet 3.0) against pyrethroid-resistant malaria vectors: a multi centre study in Western and Central Africa. Malaria J, 9, 113.

• ·         This study showed that PermaNet® 3.0 caused better efficacy against both kdr and metabolic resistant malaria vectors than PermaNet® 2.0.

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Abstract below; full text is at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781025/?tool=pubmed

Impact of insecticide-treated nets on wild pyrethroid resistant Anopheles epiroticus population from southern Vietnam tested in experimental huts

Wim Van Bortel, ¹ Vu Duc Chinh,² Dirk Berkvens,³ Niko Speybroeck,³ Ho Dinh Trung,² and Marc Coosemans^1,4

¹Institute of Tropical Medicine, Dept of Parasitology, Nationalestraat 155, B-2000 Antwerpen, Belgium

²National Institute of Malariology, Parasitology and Entomology, Dept of Entomology, Luong The Vinh street, B.C. 10.200 Tu Liem, Hanoi, Vietnam

³Institute of Tropical Medicine, Dept of Animal Health, Nationalestraat 155, B-2000 Antwerpen, Belgium

⁴Department of Biomedical Sciences, Faculty of Pharmaceutical, Veterinary and Biomedical Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen (Wilrijk), Belgium

Corresponding author.

Wim Van Bortel: wvbortel@itg.be ; Vu Duc Chinh: chinh_vu99@yahoo.com ; Dirk Berkvens: dberkvens@itg.be ; Niko Speybroeck: nspeybroeck@itg.be ; Ho Dinh Trung: hodinhtrung@fpt.vn ; Marc Coosemans: mcoosemans@itg.be

Received July 20, 2009; Accepted October 29, 2009.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

This article has been cited by other articles in PMC.

Abstract

Background

In this study, the efficacy of insecticide-treated nets was evaluated in terms of deterrence, blood-feeding inhibition, induced exophily and mortality on a wild resistant population of Anopheles epiroticus in southern Vietnam, in order to gain insight into the operational consequences of the insecticide resistance observed in this malaria vector in the Mekong delta.

Method

An experimental station, based on the model of West Africa and adapted to the behaviour of the target species, was built in southern Vietnam. The study design was adapted from the WHO phase 2 guidelines. The study arms included a conventionally treated polyester net (CTN) with deltamethrin washed just before exhaustion, the WHO recommended long-lasting insecticidal net (LLIN) PermaNet 2.0^® unwashed and 20 times washed and PermaNet 3.0^®, designed for the control of pyrethroid resistant vectors, unwashed and 20 times washed.

Results

The nets still provided personal protection against the resistant An. epiroticus population. The personal protection ranged from 67% for deltamethrin CTN to 85% for unwashed PermaNet 3.0. Insecticide resistance in the An. epiroticus mosquitoes did not seem to alter the deterrent effect of pyrethroids. A significant higher mortality was still observed among the treatment arms despite the fact that the An. epiroticus population is resistant against the tested insecticides.

Conclusion

This study shows that CTN and LLINs still protect individuals against a pyrethroid resistant malaria vector from the Mekong region, where insecticide resistance is caused by a metabolic mechanism. In the light of a possible elimination of malaria from the Mekong region these insights in operational consequences of the insecticide resistance on control tools is of upmost importance.

Copyright ©2010 Tungu et al; licensee BioMed Central Ltd.

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Evaluation of PermaNet 3.0 a deltamethrin-PBO combination net against Anopheles gambiae and pyrethroid resistant Culex quinquefasciatus mosquitoes: an experimental hut trial in Tanzania

Patrick Tungu,^1,2 Stephen Magesa,^1,2 Caroline Maxwell,^1,2,4 Robert Malima,^1,2 Dennis Masue,^1,2 Wema Sudi,^1,2 Joseph Myamba,^1,2 Olivier Pigeon,³ and Mark Rowland ^2,4

¹Amani Medical Research Centre, National Institute for Medical Research, PO Box 81, Muheza, Tanzania

²Pan-African Malaria Vector Research Consortium, Tanzania

³Pesticides Research Department, Walloon Agricultural Research Centre, 11 Rue du Bordia, B-5030 Gembloux, Belgium

⁴Department of Infectious Diseases, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK

Corresponding author.

Patrick Tungu: Patrickkijatungu@hotmail.com; Stephen Magesa: smagesa@hotmail.com  Caroline Maxwell: Caroline.maxi@gmail.com; Robert Malima: r_malima@hotmail.com; Dennis Masue: dmasue@hotmail.com; Wema Sudi: sswema@yahoo.com; Joseph Myamba: smagesa@hotmail.com; Olivier Pigeon: pigeon@cra.wallonie.be  Mark Rowland: mark.rowland@lshtm.ac.uk

Received June 9, 2009; Accepted January 19, 2010.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Full text, with figures, is at http://www.malariajournal.com/content/9/1/21

This article has been cited by other articles in PMC.

o 

Abstract

Background

Combination mosquito nets incorporating two unrelated insecticides or insecticide plus synergist are designed to control insecticide resistant mosquitoes. PermaNet 3.0 is a long-lasting combination net incorporating deltamethrin on the side panels and a mixture of deltamethrin and synergist piperonyl butoxide (PBO) on the top panel. PBO is an inhibitor of mixed function oxidases implicated in pyrethroid resistance.

Method

An experimental hut trial comparing PermaNet 3.0, PermaNet 2.0 and a conventional deltamethrin-treated net was conducted in NE Tanzania using standard WHOPES procedures. The PermaNet arms included unwashed nets and nets washed 20 times. PermaNet 2.0 is a long-lasting insecticidal net incorporating deltamethrin as a single active.

Results

Against pyrethroid susceptible Anopheles gambiae the unwashed PermaNet 3.0 showed no difference to unwashed PermaNet 2.0 in terms of mortality (95% killed), but showed differences in blood-feeding rate (3% blood-fed with PermaNet 3.0 versus 10% with PermaNet 2.0). After 20 washes the two products showed no difference in feeding rate (10% with 3.0 and 9% with 2.0) but showed small differences in mortality (95% with 3.0 and 87% with 2.0). Against pyrethroid resistant Culex quinquefasciatus, mediated by elevated oxidase and kdr mechanisms, the unwashed PermaNet 3.0 killed 48% and PermaNet 2.0 killed 32% but after 20 washes there was no significant difference in mortality between the two products (32% killed by 3.0 and 30% by 2.0). For protecting against Culex PermaNet 3.0 showed no difference to PermaNet 2.0 when either unwashed or after 20 washes; both products were highly protective against biting. Laboratory tunnel bioassays confirmed the loss of biological activity of the PBO/deltamethrin-treated panel after washing.

Conclusion

Both PermaNet products were highly effective against susceptible Anopheles gambiae. As a long-lasting net to control or protect against pyrethroid resistant mosquitoes PermaNet 3.0 showed limited improvement over PermaNet 2.0 against Culex quinquefasciatus.

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Malar J. 2010 Apr 27;9:113.

Field efficacy of a new mosaic long-lasting mosquito net (PermaNet 3.0) against pyrethroid-resistant malaria vectors: a multi centre study in Western and Central Africa.

Full text is at http://www.malariajournal.com/content/9/1/113

Corbel V, Chabi J, Dabiré RK, Etang J, Nwane P, Pigeon O, Akogbeto M, Hougard JM.

Institut de Recherche pour le Développement, UR016, Caractérisation et Contrôle des Populations de Vecteurs, 01 BP 4414 RP Cotonou, République du Bénin. vincent.corbel@ird.fr

Abstract

BACKGROUND: Due to the spread of pyrethroid-resistance in malaria vectors in Africa, new strategies and tools are urgently needed to better control malaria transmission. The aim of this study was to evaluate the performances of a new mosaic long-lasting insecticidal net (LLIN), i.e. PermaNet 3.0, against wild pyrethroid-resistant Anopheles gambiae s.l. in West and Central Africa.

METHODS: A multi centre experimental hut trial was conducted in Malanville (Benin), Vallée du Kou (Burkina Faso) and Pitoa (Cameroon) to investigate the exophily, blood feeding inhibition and mortality induced by PermaNet 3.0 (i.e. a mosaic net containing piperonyl butoxide and deltamethrin on the roof) comparatively to the WHO recommended PermaNet 2.0 (unwashed and washed 20-times) and a conventionally deltamethrin-treated net (CTN).

RESULTS: The personal protection and insecticidal activity of PermaNet 3.0 and PermaNet 2.0 were excellent (>80%) in the "pyrethroid-tolerant" area of Malanville. In the pyrethroid-resistance areas of Pitoa (metabolic resistance) and Vallée du Kou (presence of the L1014F kdr mutation), PermaNet 3.0 showed equal or better performances than PermaNet 2.0. It should be noted however that the deltamethrin content on PermaNet 3.0 was up to twice higher than that of PermaNet 2.0. Significant reduction of efficacy of both LLIN was noted after 20 washes although PermaNet 3.0 still fulfilled the WHO requirement for LLIN.

CONCLUSION: The use of combination nets for malaria control offers promising prospects. However, further investigations are needed to demonstrate the benefits of using PermaNet 3.0 for the control of pyrethroid resistant mosquito populations in Africa.