A new study led by the University of Oxford suggests that more insecticide-treated malaria nets (ITNs) and improved efficiency in net delivery are needed to achieve universal coverage and make serious headway on the path to the elimination of the disease.
Currently, malaria net coverage remains well below the 100% universal coverage target. Estimates for the number of nets needed to achieve 100% coverage are also too low, say the researchers, because of diminishing returns caused by inefficiencies in net delivery.
The study is published in the journal eLife.
‘Insecticide-treated nets, which comprise conventional and long-lasting insecticidal nets (LLINs), are the single most widely used intervention for malaria control in Africa, but coverage remains inadequate,’ says lead author Dr Samir Bhatt of the Malaria Atlas Project in Oxford’s Department of Zoology.
‘Sub-Saharan African countries at risk of malaria have calculated that 920 million ITNs would be needed across the continent to achieve national coverage targets between 2014 and 2017, but this figure does not take system inefficiencies into account.’
The team has created a mathematical model describing the use and distribution of nets across Africa since 2000. By gathering data on ITN distribution, delivery and coverage, they have provided new insights into two key inefficiencies, namely net loss and over-allocation.
The model estimates that in 2013, only 43% of people at risk of malaria slept under a net. Furthermore, the researchers estimate that rates of ITN loss from households are more rapid than previously thought, with on average 50% lost after 23 months. An average of 21% of ITNs were over-allocated in 2013, and this has worsened over time as overall net provision has increased.
‘Over-allocating nets becomes a major barrier to achieving universal coverage when ITN provision is high, because most new incoming nets simply lead to surpluses in many households while shortfalls remain elsewhere,’ Dr Bhatt explains.
The study suggests that the current estimate of 920 million additional nets needed to achieve universal coverage between 2014 and 2017 would in reality yield diminishing returns and a lower-than-expected level of coverage, with only 77% of the population able to access them.
With minimal over-allocation and longer ITN retention times, however, the 920 million nets could approach the goal of universal population access. Improving inefficiencies must therefore be considered in line with providing larger volumes of nets if higher coverage is to be achieved, say the researchers.