East Africa is reporting mixed results in its use of and access to insecticide-treated bed nets (ITNs), which have been crucial in the fight against malaria infections since the 1990s.
While Uganda and Kenya are mentioned positively in surveys on the use and distribution of ITNS, Tanzania and Burundi feature in lists of countries that are recording drops over the past 20 years.
The "Maps and metrics of insecticide-treated net access, use, and nets-per-capita in Africa from 2000-2020" survey released on June 11, shows that only 14 of these 40 African countries, among them Uganda, have ever achieved 80 percent access or use as per the World Health Organisation benchmark for universal coverage.
When planning mass campaigns, WHO recommends that countries procure one net per 1.8 people at risk to ensure universal access.
In 2020, Uganda, Benin, Mali, Niger and Togo, were the only countries estimated to achieve over 80 percent use. This was sustained by historically large campaigns completed in 2020 despite Covid-related disruptions.
Burundi, Gambia, and Ghana have seen particularly steep coverage declines in recent years, while Kenya, Sierra Leone, Burkina Faso, Malawi, and Mozambique, may distribute sufficient nets for universal coverage within the next one or two mass campaigns. Countries such as Tanzania, Cote d'Ivoire and Liberia, have lost ground or stalled progress.
In 2020, with the exception of western Tanzania and scattered areas of the Sahel, lack of access to a net was a far greater barrier to coverage than deficiencies in use.
Madagascar, which has a strong culture of net use despite limited access, shows slightly higher use than access in many years, suggesting the widespread practice of more than two people sharing a net.
Ghana, Nigeria, and Zimbabwe experienced a considerable use gap beginning in 2010.
The survey, funded by the Bill & Melinda Gates Foundation, found that mass net distributions have rarely reached all those in need to attain universal coverage despite the prodigious effort by national malaria programmes.
"We found that ITN distributions increased enormously since 2000 and those who own nets tend to use them, but a combination of insufficient net volume, distribution inefficiency, and short retention times keep ITN access and use below the WHO targets of 80 percent coverage," said the report authored by Peter W. Gething, the Kerry M. Stokes AC, chair of Child Health at Curtin University, Australia, and Samir Bhatt, a researcher at the Department of Public Health at University of Copenhagen.
As is to be expected, use is high among those with access. For populations with nets, the use rate has increased with small fluctuations across the time series examined, from a low of 71.3 percent in 2004 to a 2020 estimate of 87.1 percent.
However the duo notes that universal ITN coverage is difficult to achieve and maintain due to the volume of nets needed, misallocations and subsequent shorter-than-expected median net retention durations.
"There is some evidence of ITNs being over allocated to more accessible households that already have sufficient nets, leaving coverage gaps for less protected hard-to-reach households," they say, "Resolving these allocative inefficiencies could dramatically increase ITN access in countries with high per-capita net coverage."
Other than logistical, geographic and cultural factors, another unacknowledged source of net misallocation is the mass campaign practice of capping the number of nets any single household can obtain, disadvantaged large households, say the investigators. Such misallocation may have an immense negative effect on the inexpensive malaria intervention.
According to the researchers' estimates, long-lasting insecticide-treated nets (LLINs) -- the primary net distributed in Africa for many years -- have been having shorter lifespans than the three-year retention time assumed by WHO and other agencies. Of the 40 countries in this analysis, 35 show LLIN median retention times of under 3 years, with an overall median value of 1.64 years.
The primary motivation for discarding a net, the study found, was the perception that it was too torn.