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Table 2 Summary of wavelet analysis and time-lagged detrended cross-correlation analysis results

From: The correlation between three teleconnections and leptospirosis incidence in the Kandy District, Sri Lanka, 2004–2019

Teleconnection index vs leptospirosis incidence

Wavelet analysis results

Time-lagged detrended cross-correlation analysis results

ENSO

 Niño 4 SSTA vs leptospirosis incidence (LI)

Two patterns of correlation/1. LI peaks after about 14 weeks = 3.3months (varies 7–19 weeks) of Niño 4 SSTA troughs.

2. LI peaks after about 23 week = 5.4 months (varies 4–35 weeks) of Niño 4 SSTA peaks

LI rises significantly 3–4 months after decline of Niño 4 SSTA and again after 9–10 months (3-month lag CCF: 0.155, 4-month lag CCF: 0.187). Second pattern correlation after 6–7-month lag is not significant.

 Niño 3.4 SSTA vs leptospirosis incidence (LI)

Two patterns of correlation/1. LI peaks after about 16 weeks = 3.7 months (varies 6-32 weeks) of Niño 3.4 SSTA troughs.

2. LI peaks after about 29 weeks = 6.8 months (varies 20–46 weeks) of Niño 3.4 SSTA peaks

LI rises significantly 4–5 months after decline of Niño 3.4 SSTA and again after 9–10 months (4-month lag CCF: 0.161, 5-month lag CCF: 0.096). Second pattern correlation after 6–7-month lag is not significant.

 Multivariate ENSO Index (MEI) vs leptospirosis incidence (LI)

LI peaks after about 1.9 months (varies 1–3 months) of MEI Index troughs

LI rises significantly 1–3 months after decline of MEI and again after 7–8 months (2-month lag CCF: 0.125). Second pattern correlation after 4–5-month lag is not significant.

 Southern Oscillation Index (SOI) vs leptospirosis incidence (LI)

LI peaks after about 2.2 months (varies 1-4 months) of SOI peaks

LI rises significantly 2–3 months after rise of SOI (2 months lag CCF: 0.086, 3 months lag CCF: 0.132)

ENSO Modoki

 ENSO Modoki Index vs leptospirosis incidence (LI)

LI peaks after about 11.5 months (varies 4.9–16.1 months) of ENSO Modoki peaks

LI rises significantly 2–4 months after decline of MEI (3-month lag CCF: 0.197)

IOD

 Indian Ocean Dipole Mode Index (DMI) vs leptospirosis incidence (LI)

LI peaks after about 24 weeks = 5.6 months (range varies 6–40 weeks) of DMI peaks

LI rises significantly 2–3 months after rise of DMI (2-month lag CCF: 0.239, 3-month lag CCF: 0.240)