Study: Gold Standard of Mosquito Nets Not Sold in Tanzanian Markets

CCP research finds that Tanzanians can only buy untreated nets, which are less effective at malaria prevention than treated ones.
untreated
©WHO/Stephenie Hollyman

In Tanzania, 1.5 million bed nets are sold commercially each year. But new research led by the Johns Hopkins Center for Communication Programs finds that nearly none of them are the insecticide-treated nets that are the gold standard for malaria prevention.

“Untreated nets dominate the market despite not providing the desired protection. There is no market for treated nets,” says Benjamin Kamala, who served as director of monitoring, evaluation and learning for the CCP-led PMI Vector Control Activity, which ended in 2024. “We believe the government should convene relevant stakeholders to ensure that treated nets are available for purchase.”

The findings, based on market surveys, were led by Kamala and published in the journal Tropical Medicine and Infectious Disease in June.

Vector control interventions such as the use of treated bed nets have contributed to a reduction in malaria transmission over the past two decades in Tanzania, from a prevalence of 18 percent in 2007 to 8 percent in 2022. Several studies have shown the value of insecticide-treated nets (ITNs) in preventing malaria.

Insecticide-treated nets are designed to protect people from mosquitoes infected by the malaria parasite as they sleep at night. They offer both a physical barrier and a chemical one, with the addition of an insecticide designed to kill mosquitoes on contact. These nets are a basic rectangular shape and size.

For decades, in Tanzania and other low-and middle-income countries, donors have distributed insecticide-treated nets to wide swaths of the population for free, through a variety of campaigns designed to ensure pregnant women, babies, school-aged children and more are protected. CCP has for years been involved in projects that have helped deliver nets to millions of people in Africa.

But free nets aren’t always available, and there is a concern that funding cuts from donors could mean fewer treated nets for people in the future.

The private sector has picked up some slack. Markets sell nets in different colors and shapes that are often much softer (which is more desirable)  than the ones distributed for free. But these nets, which range in price from $2 to $10, are not treated with mosquito-killing insecticide. While this means they can be somewhat effective for individuals, these nets do nothing to help with efforts to eliminate malaria. Treated nets cost more, Kamala says.

Treated nets stop transmission. Untreated nets allow mosquitoes to go on to bite someone else.

“While it is generally a positive thing that people are buying and using these untreated nets, it could be more effective,” says Dana Loll, a research and evaluation officer at CCP who worked on the study. “We have an opportunity to better contribute to malaria elimination through the use of legitimate insecticide treated nets.”

The findings, Kamala says, suggest that the government conduct research among consumers to identify factors that will trigger them to shift from buying an untreated net to sourcing an insecticide-treated one. He says that Tanzania should look at whether tariffs or other types of regulations could help grow the insecticide-treated net market and look at ways to procure treated nets that come in shapes beyond rectangle that some people prefer.

“Any future government action should seek to maintain and build – and not undermine – the mosquito net use culture that exists in Tanzania,” the authors write.

Says Kamala: “The demand for untreated nets shows that personal investment in malaria vector control is a choice for some consumers. This demand could help fill inevitable gaps that will be created by the current reductions in malaria funding from international donors and the expected reduction in government vector control budgets. Against a backdrop of potential decreasing access to donor-funded insecticide-treated nets, the consistent use of commercially procured untreated nets could play an increasing role in malaria control through bite prevention.”

Persistence of Untreated Bed Nets in the Retail Market in Tanzania: A Cross-Sectional Survey” was written by Benjamin Kamala, Dana Loll, Ruth Msolla, David Dadi, Peter Gitanya, Charles Mwalimu, Frank Chacky, Stella Kajange, Mwinyi Khamis, Sarah-Blythe Ballard, Naomi Serbantez and Stephen Poyer.

This work was funded by the U.S. President’s Malaria Initiative (PMI) under the terms of USAID/JHU contract number 72062120C00001.

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