Seasonality of influenza in Brazil:

a traveling wave from the Amazon to the subtropics

Wladimir J Alonso, Cecile Viboud, Lone Simonsen, Eduardo W. Hirano, Luciane Z. Daufenbach, Mark Miller

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Influenza circulation and mortality impact in tropical areas have not been well characterized. The authors studied the seasonality of influenza throughout Brazil, a geographically diverse country, by modeling influenza-related mortality and laboratory surveillance data. Monthly time series of pneumonia and influenza mortality were obtained from 1979 to 2001 for each of the 27 Brazilian states. Detrended time series were analyzed by Fourier decomposition to describe the amplitude and timing of annual and semiannual epidemic cycles, and the resulting seasonal parameters were compared across latitudes, ranging from the equator (+5 degrees N) to the subtropics (-35 degrees S). Seasonality in mortality was most pronounced in southern states (winter epidemics, June-July), gradually attenuated toward central states (15 degrees S) (p < 0.001), and remained low near the equator. A seasonal southward traveling wave of influenza was identified across Brazil, originating from equatorial and low-population regions in March-April and moving toward temperate and highly populous regions over a 3-month period. Laboratory surveillance data from recent years provided independent confirmation that mortality peaks coincided with influenza virus activity. The direction of the traveling wave suggests that environmental forces (temperature, humidity) play a more important role than population factors (density, travel) in driving the timing of influenza epidemics across Brazil.
OriginalsprogEngelsk
TidsskriftAmerican Journal of Epidemiology
Vol/bind165
Udgave nummer12
Sider (fra-til)1434–1442
ISSN0002-9262
StatusUdgivet - 2007

Citer dette

Alonso, W. J., Viboud, C., Simonsen, L., Hirano, E. W., Daufenbach, L. Z., & Miller, M. (2007). Seasonality of influenza in Brazil: a traveling wave from the Amazon to the subtropics. American Journal of Epidemiology, 165(12), 1434–1442.
Alonso, Wladimir J ; Viboud, Cecile ; Simonsen, Lone ; Hirano, Eduardo W. ; Daufenbach, Luciane Z. ; Miller, Mark. / Seasonality of influenza in Brazil: a traveling wave from the Amazon to the subtropics. I: American Journal of Epidemiology. 2007 ; Bind 165, Nr. 12. s. 1434–1442.
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abstract = "Influenza circulation and mortality impact in tropical areas have not been well characterized. The authors studied the seasonality of influenza throughout Brazil, a geographically diverse country, by modeling influenza-related mortality and laboratory surveillance data. Monthly time series of pneumonia and influenza mortality were obtained from 1979 to 2001 for each of the 27 Brazilian states. Detrended time series were analyzed by Fourier decomposition to describe the amplitude and timing of annual and semiannual epidemic cycles, and the resulting seasonal parameters were compared across latitudes, ranging from the equator (+5 degrees N) to the subtropics (-35 degrees S). Seasonality in mortality was most pronounced in southern states (winter epidemics, June-July), gradually attenuated toward central states (15 degrees S) (p < 0.001), and remained low near the equator. A seasonal southward traveling wave of influenza was identified across Brazil, originating from equatorial and low-population regions in March-April and moving toward temperate and highly populous regions over a 3-month period. Laboratory surveillance data from recent years provided independent confirmation that mortality peaks coincided with influenza virus activity. The direction of the traveling wave suggests that environmental forces (temperature, humidity) play a more important role than population factors (density, travel) in driving the timing of influenza epidemics across Brazil.",
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Alonso, WJ, Viboud, C, Simonsen, L, Hirano, EW, Daufenbach, LZ & Miller, M 2007, 'Seasonality of influenza in Brazil: a traveling wave from the Amazon to the subtropics', American Journal of Epidemiology, bind 165, nr. 12, s. 1434–1442.

Seasonality of influenza in Brazil: a traveling wave from the Amazon to the subtropics. / Alonso, Wladimir J; Viboud, Cecile; Simonsen, Lone; Hirano, Eduardo W.; Daufenbach, Luciane Z.; Miller, Mark.

I: American Journal of Epidemiology, Bind 165, Nr. 12, 2007, s. 1434–1442.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Seasonality of influenza in Brazil:

T2 - a traveling wave from the Amazon to the subtropics

AU - Alonso, Wladimir J

AU - Viboud, Cecile

AU - Simonsen, Lone

AU - Hirano, Eduardo W.

AU - Daufenbach, Luciane Z.

AU - Miller, Mark

PY - 2007

Y1 - 2007

N2 - Influenza circulation and mortality impact in tropical areas have not been well characterized. The authors studied the seasonality of influenza throughout Brazil, a geographically diverse country, by modeling influenza-related mortality and laboratory surveillance data. Monthly time series of pneumonia and influenza mortality were obtained from 1979 to 2001 for each of the 27 Brazilian states. Detrended time series were analyzed by Fourier decomposition to describe the amplitude and timing of annual and semiannual epidemic cycles, and the resulting seasonal parameters were compared across latitudes, ranging from the equator (+5 degrees N) to the subtropics (-35 degrees S). Seasonality in mortality was most pronounced in southern states (winter epidemics, June-July), gradually attenuated toward central states (15 degrees S) (p < 0.001), and remained low near the equator. A seasonal southward traveling wave of influenza was identified across Brazil, originating from equatorial and low-population regions in March-April and moving toward temperate and highly populous regions over a 3-month period. Laboratory surveillance data from recent years provided independent confirmation that mortality peaks coincided with influenza virus activity. The direction of the traveling wave suggests that environmental forces (temperature, humidity) play a more important role than population factors (density, travel) in driving the timing of influenza epidemics across Brazil.

AB - Influenza circulation and mortality impact in tropical areas have not been well characterized. The authors studied the seasonality of influenza throughout Brazil, a geographically diverse country, by modeling influenza-related mortality and laboratory surveillance data. Monthly time series of pneumonia and influenza mortality were obtained from 1979 to 2001 for each of the 27 Brazilian states. Detrended time series were analyzed by Fourier decomposition to describe the amplitude and timing of annual and semiannual epidemic cycles, and the resulting seasonal parameters were compared across latitudes, ranging from the equator (+5 degrees N) to the subtropics (-35 degrees S). Seasonality in mortality was most pronounced in southern states (winter epidemics, June-July), gradually attenuated toward central states (15 degrees S) (p < 0.001), and remained low near the equator. A seasonal southward traveling wave of influenza was identified across Brazil, originating from equatorial and low-population regions in March-April and moving toward temperate and highly populous regions over a 3-month period. Laboratory surveillance data from recent years provided independent confirmation that mortality peaks coincided with influenza virus activity. The direction of the traveling wave suggests that environmental forces (temperature, humidity) play a more important role than population factors (density, travel) in driving the timing of influenza epidemics across Brazil.

KW - Brazil

KW - climate

KW - geographic locations

KW - influenza

KW - human

KW - mortality

KW - pneumonia

KW - seasons

M3 - Journal article

VL - 165

SP - 1434

EP - 1442

JO - American Journal of Epidemiology

JF - American Journal of Epidemiology

SN - 0002-9262

IS - 12

ER -