Coating formulation change is the root cause for inferior bioefficacy of long-lasting insecticidal nets in Papua New Guinea

Abstract

In a study published in Nature Communications in August 2020, we demonstrated an abrupt decrease in the bioefficacy of long-lasting insecticidal nets (LLINs) for malaria prevention delivered to Papua New Guinea (PNG) between 2012 and 2013. This coincided with a rise in malaria cases in the country. At the time of publication of the original article, we were unable to pinpoint the exact reasons for the observed shift towards inferior product performance and stated that "further studies are required to determine the underlying cause of the observed reduced bioefficacy of these LLINs" 1. Due to the potentially significant public health implications (hundreds of millions of this specific LLIN product had been distributed globally), our study led to discussions and speculation among stakeholders. Here, we present data unequivocally showing that the observed reduction in the ability to kill mosquitoes of these LLINs is a direct result of a manufacturing change that occurred at the same time.

A review of malaria epidemiology and control in Papua New Guinea 1900 to 2021: Progress made and future directions

“…This earlier outdoor biting renders indoor vector control measures such as LLIN use and IRS less effective, increases exposure to infectious mosquito bites among people gathering or working outdoors in the early evening or morning, and may pose a substantial challenge to contemporary malaria control programs ( 23 , 25 , 47 , 49 ). In addition to changes in biting behavior, recent evidence suggests a decrease in bioefficacy of LLINs distributed in PNG between 2012 and 2013 due to a change in the coating formulation of LLINs during manufacturing ( 94 , 95 ). The durability of time period within which LLINs remain effective in PNG is also uncertain, and these factors may have a large impact on current and future malaria control efforts.…”