Stephen Lim

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Nets protect against malaria, scientists say (but you already knew that) | 

Global health number crunchers, led by Seattle’s Institute for Health Metrics and Evaluation, have determined after an exhaustive survey of medical and demographic records in 22 sub-Saharan African countries that treated bed nets do protect against malaria.

Duh, you say.

Flickr, 4Cheungs

You might well think it’s a no-brainer to ask if handing out hundreds of millions of insecticide-treated bed nets in sub-Saharan Africa helps to reduce malaria.

But it’s not.

To begin with, there are lots of things that can — and do — reduce the incidence of malaria deaths and illnesses. There is the practice of indoor household spraying of insecticide, which has been increased along with the massive campaign to distribute insecticide-treated nets (ITNs).

There also seems to be a routine ebb-and-flow of malaria severity in the tropics. The disease, like many things in nature, tends to alternate between severe and mild cycles. It’s not clear why.

Flickr, Aya Rosen

And there was this confusing report recently, about the unexplained decline in mosquito populations in parts of Africa. This happened even in places where nobody was spraying or using bed nets.

There’s changes in rainfall patterns and land use that affect mosquito breeding. There are changes in access to malaria drugs (which has also been increased in recent years). And there’s a chronic problem of misdiagnosis of malaria in poor communities lacking labs. Continue reading