World Malaria Day 2026

Malaria remains a major public health challenge in regions such as Papua New Guinea and the Solomon Islands. Despite decades of progress using insecticide-treated nets (ITNs) and other interventions, recent research highlights a concerning resurgence.

To celebrate World Malaria Day 2026, we invited Assoc Prof Stephan Karl (James Cook University and Papua New Guinea Institute of Medical Research), an expert in surveillance and control of malaria and arboviruses, to explain why malaria control efforts can fail—not due to lack of tools, but due to declining performance and systemic challenges.

Here are his own words on this important matter.

Papua New Guinea and the Solomon Islands remain among the most significant malaria-endemic settings outside sub-Saharan Africa. These are environments where malaria control is inherently challenging—remote communities, limited infrastructure, and high delivery costs mean that every intervention must work efficiently and reliably.

In such settings, success depends heavily on a small number of highly effective tools. Chief among them are insecticide-treated nets (ITNs), which have been the backbone of malaria control for decades.

For a long time, these countries held an important advantage. Unlike much of Africa, they avoided widespread pyrethroid resistance in mosquito populations. This should have helped sustain the effectiveness of ITNs.

And yet, malaria resurged.

Over the past decade, research led by Stephan Karl and colleagues at the Papua New Guinea Institute of Medical Research and James Cook University has provided important insights into this question.

A series of laboratory and field studies demonstrated that ITNs distributed in Papua New Guinea experienced a marked reduction in insecticidal efficacy compared to earlier products (1,2). Critically, this decline was linked not to the emergence of insecticide resistance, but to changes in ITN manufacturing processes (3).

These findings resolve the apparent paradox. While the underlying cause differs, the outcome is the same: nets that are less effective at killing mosquitoes provide less protection.

This is not about assigning blame, but about recognising a fundamental principle: product performance matters just as much as coverage and use. Whether reduced efficacy arises from biological or manufacturing factors, the implications for malaria control are identical.

From a public health perspective, this distinction is not meaningful. If ITNs fail to kill mosquitoes, they fail to deliver protection—regardless of the reason.

This requires a more consistent application of the same principle across all settings: maintaining high and sustained insecticidal efficacy must be non-negotiable, whether the threat arises from resistance or from variation in product performance.

A key challenge is that current procurement systems treat all WHO-prequalified pyrethroid-only ITNs as equivalent. In practice, however, there are substantial differences in insecticidal performance between these products (1–3). When price becomes the dominant procurement criterion, these differences risk being overlooked.

Recognizing and acting on these differences is essential. If insecticidal performance underpins epidemiological impact, then products that deliver higher and more durable insecticidal efficacy should be prioritized, while those that do not should be reconsidered.

World Malaria Day is an opportunity to celebrate progress—but also to refine our approach.

We know that ITNs work when they maintain strong insecticidal efficacy. We also know that when this efficacy declines, malaria can return—even in the absence of resistance.

The implication is clear: what matters is not why efficacy is lost, but that it is lost—and that the response must be the same.

Evidence from Papua New Guinea provides a clear reminder that maintaining effectiveness is not guaranteed—it must be actively ensured.

Recognizing this consistently across all settings will help ensure that the tools we rely on continue to deliver the impact we expect.

Because in the end, malaria control depends not just on having the right tools—but on making sure they work, everywhere they are used.