Supplementary online materials
Title: Indian Ocean Dipole drives malaria resurgence in East African highlands
Masahiro Hashizume1*, Luis Fernando Chaves2, Noboru Minakawa1*
1
Institute of Tropical Medicine (NEKKEN) and the Global Center of Excellence program on Tropical and
Emerging Infectious Diseases, Nagasaki University, Nagasaki, Japan
2
Graduate School of Environmental Sciences and Global Center of Excellence program on Integrated
Field Environmental Science, Hokkaido University, Sapporo, Japan
Table 1 Model Selection. Time series indicates the malaria time series, autoregressive components indicate the
number of ordinary and seasonal autoregressive components respectively. Covariates indicate the different
covariates with the respective lag, in months, within parenthesis: Trend is the non-linear trend obtained using
loess, Rainfall, the local rainfall (in Maseno and Kendu Bay, rainfall from Kisumu was used as a proxy); Nino3, the
Niño 3 index and DMI, the dipole mode index. Breakpoint indicates whether a breakpoint was considered (Y) or
not (N) and AIC indicates the Akaike Information criterion, highlighted values show the best models (with minimum
AIC).
Time Series
Maseno
Kendu Bay
Kisii
Kapsabet
Autoregressive Autoregressive
components
components
(Seasonal)
1
1
1
1
1
1
1
1
1
1
2
2
1
0
2
0
2
0
1
1
1
0
1
0
2
2
1
0
2
0
2
0
2
0
Kericho
Covariates
Breakpoint
AIC
Trend
Trend, Rainfall(3)
Trend, Rainfall(3)
Trend
Trend, Rainfall(0),
Rainfall(3), dmi(35)
Trend
Trend
Trend, Rainfall(2),
dmi(2)
Trend, Rainfall(2),
dmi(2)
Trend
Trend
Trend, Rainfall (2),
Rainfall (6)
Trend
Trend
Trend, Rainfall(3),
Nino3(2), dmi (1)
Trend, Rainfall(3),
dmi (1)
Trend, Rainfall(3),
dmi (1)
N
N
Y
N
3069.2
3063.1
3024.4
3226.69
N
3211
N
N
2685
2685
N
2668.4
Y
2613.48
N
N
2963.08
2961.13
N
2943.72
N
N
4551.05
4549.37
N
4543.21
N
4542.33
Y
4482.88
Supplementary figure legends
Fig. s1 Autocorrelation (ACF) and cross-correlation functions (CCF) (A) Maseno malaria
ACF; (B) Maseno malaria and Kisumu rainfall CCF; (C) Maseno malaria and Dipole mode
index, dmi, CCF; (D) Maseno malaria and the Niño 3 index, Nino3; (E) Kendu Bay malaria
ACF; (F) Kendu Bay malaria and Kisumu rainfall CCF; (G) Kendu Bay malaria and dmi CCF;
(H) Kendu Bay and Nino3 CCF; (I) Kisii malaria ACF; (J) Kisii malaria and rainfall CCF; (K)
Kisii malaria and dmi CCF; (L) Kisii malaria and Nino3 CCC; (M) Kapsabet malaria ACF; (N)
Kapsabet and rainfall CCF; (O) Kapsabet malaria and dmi CCF; (P) Kapsabet malaria and Nino3
CCF; (Q) Kericho malaria ACF; (R) Kericho malaria and rainfall CCF; (S) Kericho malaria and
dmi CCF; (T) Kericho malaria and Nino3 CCF.
Fig. s2 Cross-wavelet coherence of the malaria time series with rainfall. (A) Maseno
(January 1980-December 2006); (B) Kendu Bay (January 1980-December 2006); (C) Kisii
(January 1986-December 2000); (D) Kapsabet (January 1980-December 1999); (E) Kericho
(January 1966 – November 2006). For Maseno and Kendu Bay rainfall records from Kisumu
where used as a proxy of local rainfall. For all other time series local rainfall series were
employed.
Fig. s3 Rainfall time series. Rainfall in: Kisumu (January 1980, December 2006, 0°6'S 34°45'E
Altitude = 1150 m) (B) Kisii (January, 1986, December 2000); (C) Kapsabet (January 1980,
December 2000); (D) Kericho (January 1966, December 2006).
Fig. s4 Cross-wavelet coherence of the rainfall time series with the DMI (dipole mode
index) and with Nino3 (ENSO index). (A) Kisumu and dmi (January 1980-December 2006);
(B) Kisumu and Nino3 (January 1980-December 2006); (C) Kisii and dmi (January 1986December 2000); (D) Kisii and Nino3 (January 1986-december 2000); (E) Kapsabet and dmi
(January 1980- December 1999); (F) Kapsabet and Nino3 (January 1980-December 1999); (G)
Kericho and dmi (January 1966-November 2006);(H) Kericho and Nino3 (January 1966November 2006). The coherency scale is from zero (blue) to one (red). Other technical details
are presented in the legend of Fig. 2
Figure s1
Figure s2
Figure s3
Figure s4