Malaria death rates have fallen 60% since 2000, but with some mosquitoes developing resistance to treated bednets, is it time to change strategy?
A pregnant woman holds a mosquito net in Cali, Colombia. Insecticide-treated bednets and other measures have averted millions of deaths, says the World Health Organisation. Photograph: Luis Robayo/AFP/Getty Images
he underlying fact seems incontrovertible: mosquito resistance to the insecticides used to treat bednets is growing. The question is what can be done to combat this resistance and ringfence the dramatic drop in global malaria deaths over the past 15 years?
Since 2000, the numbers of people dying of malaria have dropped by 60% and cases of the disease have fallen by 37%, according to the World Health Organisation (WHO).
Insecticide-treated bednets, indoor and outdoor spraying, and other measures have averted millions of deaths, the WHO’s 2015 malaria report found. Research published in Nature and included in the report showed that bednets had been “by far the most important intervention” across Africa, accounting for an estimated 68% of cases prevented since 2000.
But the report highlighted concern about mosquito resistance to insecticides used in bednets or indoor spraying. The evidence of resistance to pyrethroids – the only insecticide class approved by the WHO for use in long-lasting bednets – has been building.
“Insecticide resistance is an important emerging threat that could potentially weaken malaria responses in many countries. Since 2010, 60 of the 78 countries that monitor resistance have reported [resilience] to at least one insecticide used in nets and indoor residual spraying,” a WHO spokesperson says.
“We do not, at this point in time, have sufficient evidence linking an increase in insecticide resistance to [cases] or death rates.”