Monday, 25th of January 2010 |
CSU 09/2010: MANAGING INSECTICIDE RESISTANCE
In the '50s and '60s, the rapid appearance of DDT resistance, with no overall strategy for managing insecticide resistance, was a major factor in defeating the global eradication efforts of those decades. Documenting the appearance of resistance is the first step towards implementation of corrective measures.
Good reading.
BD
1) 'Insecticide resistance in Anopheles gambiae: data from the first year of a multi-country study highlight the extent of the problem'
Hilary Ranson*1, Hiba Abdallah2, Athanase Badolo3,4, Wamdaogo Moussa Guelbeogo3, Clément Kerah-Hinzoumbé5, Elise Yangalbé-Kalnoné5, N'Falé Sagnon3, Frédéric Simard6 and Maureen Coetzee7,8
Address: 1Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK, 2Vector Biology & Control unit, Blue Nile National Institute for Communicable Disease, PO Box 101, Wad Medani, Sudan, 3Centre National de Recherche et de Formation sur le Paludisme 01 BP 2208 Ouagadougou 01, Burkina Faso, 4Université de Ouagadougou, BP 7021, Ouagadougou 03, Burkina Faso, 5National Malaria Control Programme BP 1043, N'Djaména, Chad, 6Institut de Recherche pour le Développement (IRD), UR016 and Institut de Recherche en Sciences de la Santé (IRSS), 01 BP 171 Bobo-Dioulasso, Burkina Faso, 7Malaria Entomology Research Unit, School of Pathology, University of the Witwatersrand, Johannesburg 2000, South Africa and 8Vector Control Reference Unit, National Institute for Communicable Diseases of the NHLS, Private Bag X4, Sandringham, Johannesburg 2131, South Africa
Email: Hilary Ranson* - hranson@liv.ac.uk; Hiba Abdallah - hiba_mohamed@hotmail.com; Athanase Badolo - a.badolo@googlemail.com; Wamdaogo Moussa Guelbeogo - guelbeogo.cnrfp@fasonet.bf; Clément Kerah-Hinzoumbé - kerah_clement@yahoo.fr; Elise Yangalbé-Kalnoné - yankael@yahoo.fr; N'Falé Sagnon - n.fale.cnlp@fasonet.bf; Frédéric Simard - Frederic.Simard@ird.fr; Maureen Coetzee - aureenc@nicd.ac.za
* Corresponding author
Background: Insecticide resistance in malaria vectors is a growing concern in many countries which requires immediate attention because of the limited chemical arsenal available for vector control. The current extent and distribution of this resistance in many parts of the continent is unknown and yet such information is essential for the planning of effective malaria control interventions.
Methods: In 2008, a network was established, with financial support from WHO/TDR, to investigate the extent of insecticide resistance in malaria vectors in five African countries. Here, the results of bioassays on Anopheles gambiae sensu lato from two rounds of monitoring from 12 sentinel sites in three of the partner countries are reported.
Results: Resistance is very heterogeneous even over relatively small distances. Furthermore, in some sites, large differences in mortality rates were observed during the course of the malaria transmission season. Using WHO diagnostic doses, all populations from Burkina Faso and Chad and two of the four populations from Sudan were classified as resistant to permethrin and/or deltamethrin. Very high frequencies of DDT resistance were found in urban areas in Burkina Faso and Sudan and in a cotton-growing district in Chad. In areas where both An. gambiae s.s. and Anopheles arabiensis were present, resistance was found in both species, although generally at a higher frequency in An gambiae s.s. Anopheles gambiae s.l. remains largely susceptible to the organophosphate fenitrothion and the carbamate bendiocarb in the majority of the sentinel sites with the exception of two sites in Burkina Faso. In the cotton-growing region of Soumousso in Burkina Faso, the vector population is resistant to all four classes of insecticide available for malaria control.
Conclusions: Possible factors influencing the frequency of resistant individuals observed in the sentinel sites are discussed. The results of this study highlight the importance of standardized longitudinal insecticide resistance monitoring and the urgent need for studies to monitor the impact of this resistance on malaria vector control activities.
Armel Djènontin1,2, Joseph Chabi2, Thierry Baldet2, Seth Irish4, Cédric Pennetier3, Jean-Marc Hougard2, Vincent Corbel*2, Martin Akogbéto1 and Fabrice Chandre3
Address: 1CREC, Cotonou, Bénin, 2CREC/IRD UR016, Cotonou, Bénin, 3LIN/IRD UR016, Montpellier, France and 4London School of Tropical
Medicine and Hygiene, London, UK
Background: Pyrethroid resistance is now widespread in Anopheles gambiae, the major vector for malaria in sub-Saharan Africa. This resistance may compromise malaria vector control strategies that are currently in use in endemic areas. In this context, a new tool for management of resistant mosquitoes based on the combination of a pyrethroid-treated bed net and carbamate-treated plastic sheeting was developed.
Methods: In the laboratory, the insecticidal activity and wash resistance of four carbamate-treated materials: a cotton/polyester blend, a polyvinyl chloride tarpaulin, a cotton/polyester blend covered on one side with polyurethane, and a mesh of polypropylene fibres was tested. These materials were treated with bendiocarb at 100 mg/m2 and 200 mg/m2 with and without a binding resin to find the best combination for
field studies. Secondly, experimental hut trials were performed in southern Benin to test the efficacy of the combined use of a pyrethroid-treated bed net and the carbamate-treated material that was the most wash-resistant against wild populations of pyrethroid-resistant An. gambiae and Culex quinquefasciatus.
Results: Material made of polypropylene mesh (PPW) provided the best wash resistance (up to 10 washes), regardless of the insecticide dose, the type of washing, or the presence or absence of the binding resin. The experimental hut trial showed that the combination of carbamate-treated PPW and a pyrethroid-treated bed net was extremely effective in terms of mortality and inhibition of blood feeding of pyrethroid-resistant An. gambiae. This efficacy was found to be proportional to the total surface of the walls. This combination showed a moderate effect against wild populations of Cx. quinquefasciatus, which were strongly resistant to pyrethroid.
Conclusion: These preliminary results should be confirmed, including evaluation of entomological, parasitological, and clinical parameters. Selective pressure on resistance mechanisms within the vector population, effects on other pest insects, and the acceptability of this management strategy in the community also need to be evaluated.
Are three drugs for malaria better than two?
Friday, 24th of April 2020 |
Public health Interventions and epidemic intensity during the 1918 influenza pandemic
Thursday, 16th of April 2020 |
Chloroquine and hydroxychloroquine as available weapons to fight COVID-19
Tuesday, 17th of March 2020 |
Using models to shape measles control and elimination strategies in low- and middle-income countries: A review of recent applications
Monday, 17th of February 2020 |
Immunization Agenda 2030
Tuesday, 11th of February 2020 |
40925431 |
www.measlesinitiative.org www.technet21.org www.polioeradication.org www.globalhealthlearning.org www.who.int/bulletin allianceformalariaprevention.com www.malariaworld.org http://www.panafrican-med-journal.com/ |