Malaria control in Papua New Guinea results in complex epidemiological changes

With a renewed interest in large-scale malaria interventions, knowledge about the possible long-term effects of such interventions on the nature of malaria transmission is essential. We document complex changes in malaria epidemiology over the last 40 years associated with changing malaria control activities in Karimui, an isolated area in Papua New Guinea. An initially equal distribution of Plasmodium falciparum, P. vivax and P. malariae changed to currently 68% P. falciparum, after passing through a phase of transitory P. vivax dominance, when control started to fail. Initial drops in malaria prevalence proved difficult to sustain and present post-control levels are significantly higher than pre-control levels. The example of Karimui indicates that unsustained control can lead to changes in malaria patterns that may leave a population worse off.