PermaNet® 3.0 - Complexities of Resistance

In malaria treatment

• ŸMalaria case management forms one of the core interventions of the global strategy for malaria control. Prompt and accurate diagnosis is needed for effective treatment.
• Chloroquine was introduced as the antimalarial medicine of choice in 1945¹.
• ŸIn the mid-seventies, chloroquine resistance became a problem in sub-Saharan Africa.
• ŸThe unprecedented scale of the then rapidly-rising resistance of Plasmodium falciparum to conventional monotherapies such as chloroquine, sulfadoxine-pyrimethamine (SP) and amodiaquine threathened global malaria control efforts².
• ŸMulti-drug resistant falciparum malaria became widespread in South-East Asia and South America. Also, Africa the entire continent with the highest burden of malaria got seriously affected by drug resistance².
• ŸIn 2004, the WHO revised malarial treatment policies, and recommended all countries to opt for a combination treatment, preferably an artemisinin-based combination therapy (ACT)². This effort not only helps in malaria control and treatment but also preserves the noble artemisinin-based antimalarial drugs.

In malaria prevention

• ŸPyrethroids are currently the only insecticide class recommended by the WHO for use on bednets, for reasons of safety, efficacy, acceptability and cost.
• No new class of insecticides has been introduced for use in public health for over 20 years.
• ŸThe extensive use and misuse of insecticides for agriculture has contributed to the development of resistance in public health^3,4 pests. Resistance in mosquitoes^5,6 has also been linked to IRS^7,8, ITNs and use of household insecticide (sprays, coils etc)⁹.
• ŸExtensive resistance development has resulted in reduced efficacy of pyrethroid-treated bednets¹⁰, which may have a negative impact on malaria prevention and control as reported in some countries. Therefore, the growing challenge in insecticide resistance under threat to vector control remains strong.

Insecticide Resistance from 45 countries Nov 2011*

References

1. Carter, R. & Mendis, K. N. (2002) Evolutionary and historical aspects of the burden of malaria. Clin
Microbiol Rev 15: 564-594.

2. http://www.who.int/malaria/docs/who_apt_position.htm

3. Djouaka, R. F. et al (2008) Expression of the cytochrome P450s, CYP6P3 and CYP6M2 are significantly elevated in multiple pyrethroid-resistant populations of Anopheles gambiae s.s. from Southern Benin and Nigeria. BMC Genomics 9: 538.

4. Chouaibou, M., J. et al (2008) Dynamics of insecticide resistance in the malaria vector Anopheles gambiae s.l. from an area of extensive cotton cultivation in Northern Cameroon. Trop Med Int Health 13: 1-11.

5. Brogdon, W.G. et al (1988) Microplate assay analysis of reduced fenitrothion susceptibility in Haitian Anopheles albimanus. J Am Mosq Control Assoc 4:152-158.

6. Lines, J.D. (1988) Do agricultural insecticides select for insecticide resistance in mosquitoes? A look at the evidence. Parasitology Today 4:S17-S20.

7. Corbel, V. et al (2004) Dosage-dependent effects of permethrin-treated nets on the behaviour of Anopheles gambiae and the selection of pyrethroid-resistance. Malar J 3: 22.

8. Stump, A. D. et al (2004) Dynamics of the pyrethroid knockdown resistance allele in western Kenyan populations of Anopheles gambiae in response to insecticidal bed net trials. Am J Trop Med Hyg 70(6): 591-596.

9. Akogbeto, M. & Yakoubou, S. (1999) Resistance of malaria vectors to pyrethrins used for impregnating mosquito nets in Benin, West Africa. Bull Soc Pathol Exot 92(2): 123-130.

10. N'Guessan, R et al (2007) Reduced efficacy of insecticide-treated nets and indoor residual spraying for malaria control in pyrethroid resistance area, Benin. Emerg Infect Dis 13(2): 199-206.