Laboratory and semi-field efficacy evaluation of permethrin–piperonyl butoxide treated blankets against pyrethroid-resistant malaria vectors oleh Salum Azizi, Johnson Matowo, Njelembo Joshua Mbewe, Natacha Protopopoff, Rashid Athumani, Wambura Matiku, Magreth Shayo, Filemoni Tenu, Mark Rowland, Franklin Mosha, Jovin Kitau