The wavelet power spectrum of the weekly series of P. falciparum (1994–2006) stratified by geographic region. In jungle regions, annual and biennial cycles dominate the beginning of the time series until about 2000 when a triennial pattern starts to show the highest power. An annual pattern in coastal regions shows almost continuously the highest power. In addition, a strong triennial pattern shows high power during 1998–2002. In mountain regions, the annual pattern shows high power during 1995–1997 and then again during 1999–2002. In addition, between 1997 and 2002 a strong triennial pattern shows high power.