| Sumario: |
Malaria resurgence in African highlands in the 1990s has raised questions about the underlying drivers of
the increase in disease incidence including the role of El-Nin ̃o-Southern Oscillation (ENSO). However,
climatic anomalies other than the ENSO are clearly associated with malaria outbreaks in the highlands. Here
we show that the Indian Ocean Dipole (IOD), a coupled ocean-atmosphere interaction in the Indian Ocean,
affected highland malaria re-emergence. Using cross-wavelet coherence analysis, we found four-year long
coherent cycles between the malaria time series and the dipole mode index (DMI) in the 1990s in three
highland localities. Conversely, we found a less pronounced coherence between malaria and DMI in lowland
localities. The highland/lowland contrast can be explained by the effects of mesoscale systems generated by
Lake Victoria on its climate basin. Our results support the need to consider IOD as a driving force in the
resurgence of malaria in the East African highlands.
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