Seasonality of influenza in Brazil: a traveling wave from the Amazon to the subtropics
- PMID: 17369609
- DOI: 10.1093/aje/kwm012
Seasonality of influenza in Brazil: a traveling wave from the Amazon to the subtropics
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.
Similar articles
-
Seasonality of influenza in the tropics: a distinct pattern in northeastern Brazil.Am J Trop Med Hyg. 2009 Jul;81(1):180-3. Am J Trop Med Hyg. 2009. PMID: 19556586
-
Effectiveness of influenza vaccination and its impact on health inequalities.Int J Epidemiol. 2007 Dec;36(6):1319-26. doi: 10.1093/ije/dym208. Epub 2007 Oct 31. Int J Epidemiol. 2007. PMID: 17977871
-
Influenza and the winter increase in mortality in the United States, 1959-1999.Am J Epidemiol. 2004 Sep 1;160(5):492-502. doi: 10.1093/aje/kwh227. Am J Epidemiol. 2004. PMID: 15321847
-
Geographic expansion of dengue: the impact of international travel.Med Clin North Am. 2008 Nov;92(6):1377-90, x. doi: 10.1016/j.mcna.2008.07.002. Med Clin North Am. 2008. PMID: 19061757 Review.
-
Global influenza seasonality: reconciling patterns across temperate and tropical regions.Environ Health Perspect. 2011 Apr;119(4):439-45. doi: 10.1289/ehp.1002383. Epub 2010 Nov 19. Environ Health Perspect. 2011. PMID: 21097384 Free PMC article. Review.
Cited by
-
Integrating dynamical modeling and phylogeographic inference to characterize global influenza circulation.medRxiv [Preprint]. 2024 Mar 15:2024.03.14.24303719. doi: 10.1101/2024.03.14.24303719. medRxiv. 2024. PMID: 38559244 Free PMC article. Preprint.
-
Machine learning in predicting severe acute respiratory infection outbreaks.Cad Saude Publica. 2024 Jan 8;40(1):e00122823. doi: 10.1590/0102-311XEN122823. eCollection 2024. Cad Saude Publica. 2024. PMID: 38198384 Free PMC article.
-
A combination of annual and nonannual forces drive respiratory disease in the tropics.BMJ Glob Health. 2023 Nov;8(11):e013054. doi: 10.1136/bmjgh-2023-013054. BMJ Glob Health. 2023. PMID: 37935520 Free PMC article.
-
Clinical Characterization of Respiratory Syncytial Virus Infection in Adults: A Neglected Disease?Viruses. 2023 Aug 31;15(9):1848. doi: 10.3390/v15091848. Viruses. 2023. PMID: 37766255 Free PMC article.
-
Repeatability and timing of tropical influenza epidemics.PLoS Comput Biol. 2023 Jul 19;19(7):e1011317. doi: 10.1371/journal.pcbi.1011317. eCollection 2023 Jul. PLoS Comput Biol. 2023. PMID: 37467254 Free PMC article.
Publication types
MeSH terms
Grants and funding
LinkOut - more resources
Full Text Sources
Medical
Miscellaneous