Documento(s) 8 de 15

Keeping Malaria at Bay: Insecticide-treated Nets

Introduction 

Nearly 30 years ago, the World Health Organization (WHO) predicted that malaria would never be eradicated. But today, for the first time since the 1950s, there is real hope of controlling the disease based on research funded in part by IDRC. Scientists in Canada and Africa have been studying a new twist on an age-old method of combating malaria — sleeping under nets that keep the deadly mosquitoes at bay. Recent large-scale studies in Kenya, Ghana, and The Gambia have proven that the innovative use of insecticide-treated nets (ITNs) is a highly effective method for controlling the spread of malaria.  

Untreated nets have long been used in the tropics, but they have to be well-maintained and used properly to be effective. By contrast, nets treated with pyrethroid insecticides (ITNs) provide much more than a physical barrier; they actually deter mosquitoes from feeding and drive them from their hiding places. Even a treated net with large holes in it provides as much protection as an intact one, reducing mosquito bites by up to 95 percent. Simple and safe to use, they lend themselves to effective community-based malaria control programs. (see General Information about mosquito nets and insecticides.) 

Spurring interest in ITNs is this harsh reality: malaria is one of the main causes of illness and death in the developing world and the leading cause in Africa, where one malaria parasite (Plasmodium falciparum) accounts for about 25 percent of all childhood deaths below age five (recent studies suggest that the percentage may even be higher). And the impact of this disease in terms of disability and lives lost continues to grow as traditional drug treatments become less effective against resistant strains of the parasite.  

Impact 

• Child mortality can be reduced - Large studies of insecticide-treated nets in The Gambia, Ghana, and Kenya have indicated that the use of this simple technology can reduce overall child mortality by 17 to 63 percent. In the Kenya study, funded largely by IDRC and WHO, ITNs reduced deaths from life-threatening malaria by 44 percent, lowered the hospitalization of children with malaria by 41 percent, and reduced childhood deaths from all causes by 33 percent. In Ghana's northern savannah, where malaria transmission rates are even higher, nets reduced childhood deaths by 17 percent.
• Based on these studies, scientists estimate that the widespread distribution and use of treated nets could save the lives of at least 500 000 children a year in Africa alone.
• Less expensive in long-term - Because ITNs can be re-used, they are expected to be less expensive in the long term than the combined cost of other prevention methods and treatment, including anti-malarial drugs (to which malaria parasites are becoming increasingly resistant), insecticide sprays, coils, and traditional control methods. Some people in Africa currently spend between five and 20 percent of their income on less effective methods ways to prevent and treat malaria.
• Economic benefits - In Benin and Côte d'Ivoire, cooperatives are now sewing and selling insecticide-treated nets. This promotes the use of nets, creates employment for women, and raises their status in the community. Work is proceeding to secure a steady supply of inexpensive netting and insecticides.
• Distribution studied - IDRC has established networks with researchers working for non-governmental organizations and other agencies across Africa to explore ways of distributing nets and encouraging their use. (A PATH Canada report on the ITN marketing and distribution project will be available in late 1997.)

Prerequisites 

Potential users 

Cost and availability 

According to PATH Canada, a net costs between CAD $5 and $10 undipped (add about CAD $0.50 for a dipped net). The cost varies by country. Polyester nets can last up to five years and have to be re-dipped every six months, a process that can be done locally.  

Future outlook 

In 1994, IDRC and TDR co-organized a Pan-African workshop to forecast research needs related to the use of ITNs for malaria control. The new agenda was published in October 1996 in the IDRC/WHO book, Net Gain. It focuses on operational research to support the use of insecticide-treated nets and assesses  how populations at risk can be effectively protected by ITNs in an affordable, sustainable, and equitable manner.  

With IDRC support, PATH Canada is researching the key constraints to the supply of, and demand for, nets and insecticides in sub-Saharan Africa. This includes exploring ways to reduce the cost of nets by changing the policies on import duties, encouraging local mass production, and providing community credit or other financial incentives. The results of this project are intended for planners developing more effective strategies for implementing ITNs at local, national, and regional levels.  

In early 1997, IDRC approved funding for a new 18-month program called the Net Gain for Africa Task Force. Housed at PATH Canada, the task force will aim to reduce morbidity and mortality from malaria — particularly among women and children — by increasing the proportion of households in sub-Saharan Africa that own and regularly use ITNs. Key to this work is developing a reference centre to provide strategic technical support for ITN projects and research.  The goal is to develop innovative, cost-effective, and sustainable strategies for promoting the use of ITNs.  

Related projects 

Contact 

Dr. Jacqueline Cattani, Bednet Task Force Manager  
Special Programme for Research and Training in Tropical Diseases (TDR)  
World Health Organization (WHO)  
CH-1211 Geneva 27, SWITZERLAND  
Tel: 41-22-791-3737/3738 
Fax: 41-22-791-4854 
Telex: 415416 
E-mail: cattanij@who.ch.  

Dr. Christian Lengeler, Bednet Mortality Trail Network Coordinator  
Swiss Tropical Institute  
Socinstrasse 57  
P.O. Box  
CH-4002 Basel, SWITZERLAND    
Tel: 41-61-284-8111 
Fax: 41-61-271-8654 
E-mail: lengeler@ubaclu.unibas.ch  

Dr. Fred Binka, Ghana Bednet Trial Leader  
Director  
Navrongo Health Research Centre  
Ghana Ministry of Health  
Navrongo, GHANA 
Tel: 233 72 3425 (connection sometimes difficult) 
E-mail: fbinka@gha2.healthnet.org  

Dr. Selim Rashed, Researcher Physician  
McGill Centre for Tropical Diseases  
Montreal, Quebec, CANADA 
Tel: (514) 374-7940 or (514) 255-6074 
E-mail: cyrd@musica.mcgill.ca  

PATH Canada  
1 Nicholas Street, Suite 1105 
Ottawa, Ontario, CANADA  K1N 7B7 
Tel: (613) 241-3927 
Fax: (613) 241-7988 
E-mail: path@synapse.net  

Resources 

General information on malaria:   
The history of malaria 
Malaria: A deadly disease  
Commonly asked questions about malaria and insecticide-treated nets  
Statistics on malaria  
Malaria and nets  
Malaria and IDRC  
WHOSIS-Malaria Information, on WHO Website  
Impregnated nets and malaria: a bibliography prepared by Alison Ball, IDRC Library  
Malaria control, PATH Canada  

Copyright 1998 © International Development Research Centre, Ottawa, Canada  

info@idrc.ca | June 15, 1998

Documento(s) 8 de 15