My first Tracking Charity story with PRI’s The World investigates a seemingly simple and promising technology: the insecticide treated bed net. Hundreds of millions of nets were distributed across Africa as part of a multibillion dollar campaign to fight malaria. The nets were supposed to last from three to five years and protect people from malaria-carrying mosquitoes.

My story from the African nation of Malawi shows how growing insecticide resistance is now compromising the power of the nets. And I meet many families who say their nets became riddled with holes after less than a year of use.

While in Malawi, I also filmed researcher Themba Mzilahowa, who is with the Malaria Alert Center. He tests mosquitoes at this lab to see how resistant the insects have become to the insecticide on bed nets: