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Is the bednet era coming to an end?

June 22, 2012 - 12:47 -- Bart G.J. Knols

Whenever I teach on the history of malaria, I talk about the different time periods when certain ideas were fashionable and implemented, and then disappeared, and sometimes came back much later.

Take the 'chloroquine era'. Discovered by Bayer scientists in the early 1930s and saved millions of lives around the globe, followed by resistance popping up in SE Asia and Colombia in the late 1950s. Resistance spreading to Africa in the late 1970s, and its use now largely reduced. End of the 'chloroquine era'.

The 'eradication era'. Following a hefty debate in Kampala in 1955 the World Health Assembly adopted the idea of global malaria eradication. Country after country became freed of the scourge, but the developing world was either not included in the campaign, or efforts failed. In 1969 the concept was abandoned and hopes deteriorated. But the era wasn't over yet: At the end of 2007 there was no life for it, when Bill & Melinda Gates, side-by-side with Margeret Chan from WHO re-launched the 'eradication era'.

The 'DDT era'. DDT, discovered in 1939, played a crucial role in countries that successfully eliminated malaria in the middle of the last century. But then we saw publication of the book 'Silent spring' by Rachel Carson, the change of public opinion towards DDT, and the ban on it in 1972. But like the eradication paradigm, DDT survived against all odds, and the Stockholm declaration in 2004 saw its re-entry in the realm of malaria control. A year later more than 4 million kg were sprayed in sub-Saharan Africa. We're back in the DDT era.

Following the early trials of dipping bednets in synthetic pyretroids (that date back to the early 1980s), in Ivory Coast in 1983, a new era started to mature. That of insecticide-treated bednets. Hope surfaced that this new tool could make a real dent in malaria. The 'bednet era' started. Evolution of the concept from dipping at six-months intervals, to K-O Tab (remember?), to long-lasting insecticide treated nets happened. We're in the middle of the 'LLIN era'. Lengeler's Cochrane review of 2004 underpins the validation to move forward with this era - nets do save lives, and massive reduce malaria episodes in target groups.

As an entrepreneur I know all to well about product life-cycles. Products come and go, because they are replaced by better products (the death of the floppy disk after being replaced by CDs), or no longer perform the way they should (my chloroquine example above - we are now in the 'ACT era').

In case we do not have another class of insecticides to impregnate bednets with (remember the dual-insecticide (pyrethroid/carbamate) impregnated nets that never really made it?) then are we moving towards the end of the 'bednet era'? Widespread resistance to pyrethroids is what we face - Janet Hemingway called it droplets of susceptibility in an ocean of resistance recently - besides nets not being used in the way they should (look at the picture below; courtesy Patrick Sampao).

What about the recent article from Benin that concluded: 'ITNs provide little or no protection once the mosquitoes become resistant and the netting acquires holes. Resistance seriously threatens malaria control strategies based on ITN'? Or read Clive Shiff's comment about the situation in Zambia.

Are we nearing the end of the 'bednet era'?

 

Comments

Submitted by Ricardo Ataide on

Hi Bart!

Nice article. Malaria has seen, as you pointed out,  its share of 'eras'. Even so, I don't believe that the bed-net era is coming to and end. Not yet. If something, the bed-net era is coming to a turning point.

It is true that there are issues with pockets of resistance, with net distribution chains, with wear and tear, with design, with acceptibility and with getting people to realise the importance of how to use the bed-nets but it is also true that they are a great tool!

From my little knowledge of this field all I can say is that from what i've been reading and what I heard at Harvard in the Science of Eradication: Malaria course, the tool that will and needs to be applied at the same time as the bed-net is community involvement, community responsibility, community surveillance.

Recently I suggested to Sumitomo the use of insecticide treated window-nets, or insecticide treated door-nets that could be installed easily and could adapt to different window and door shapes. This would not only avoid the nuissance of having to put up a bed net everynight, but also protect everyone in the house.  A bit to my surprise (or maybe I shouldn't have thouht I was that bright!) I was told that these were things already being developed. I also, suggested having bed-nets with velcro-detachable sections that could be replaced easily to replace those areas of the nets that are more prone to be torn. Of course that all of this will increase the costs of the nets and eventually a hard decision will have to be made.

A lot of work is being put into new designs, new insecticide combinations and carriers and new distribution chains but it is true that this will require a lot of funds also. Who will, or more importantly who should pay for it? That is another ballgame entirely.
 
So, the bed-net era is not over yet but the 'house-net' era might start soon...

Ricardo Ataíde