Seasonality of Infectious Diseases

David N Fisman

doi:10.1146/annurev.publhealth.28.021406.144128

David N Fisman

Open Access

https://doi.org/10.1146/annurev.publhealth.28.021406.144128

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Abstract

Seasonality, a periodic surge in disease incidence corresponding to seasons or other calendar periods, characterizes many infectious diseases of public health importance. The recognition of seasonal patterns in infectious disease occurrence dates back at least as far as the Hippocratic era, but mechanisms underlying seasonality of person-to-person transmitted diseases are not well understood. Improved understanding will enhance understanding of host-pathogen interactions and will improve the accuracy of public health surveillance and forecasting systems. Insight into seasonal disease patterns may be gained through the use of autocorrelation methods or construction of periodograms, while seasonal oscillation of infectious diseases can be easily simulated using simple transmission models. Models demonstrate that small seasonal changes in host or pathogen factors may be sufficient to create large seasonal surges in disease incidence, which may be important particularly in the context of global climate change. Seasonality represents a rich area for future research.

Highlights

Seasonality, a periodic surge in disease incidence corresponding to seasons or other stereotyped calendar periods, is characteristic of many infectious diseases of public health importance [24]
As Dowell & Ho [24] wrote in the aftermath of the 2003 outbreak of coronavirus-associated severe acute respiratory syndrome (SARS), Nearly every important respiratory pathogen of human beings exhibits distinct seasonal variations, yet after hundreds of years of observing and documenting this phenomenon modern science has only superficial observations and largely untested theories about the underlying causes. Is it the cold? Dry air? Crowding together of people indoors in winter? Where do pathogens such as influenza and respiratory syncytial virus (RSV) go in the summertime? Do they migrate across the equator and return the following winter, or do they remain present at low levels in human or animal populations until environmental or host conditions are suitable for re-emergence?
In aggregating legionellosis and pneumococcal disease incidence by season of occurrence for Philadelphia county, one finds that an increased risk of pneumococcal disease is seen in wintertime relative to other seasons [incidence rate ratio (IRR) 1.50, 95% CI 1.21 to 1.85], whereas the risk of legionellosis is increased in summer relative to other seasons (IRR 3.63, 95% CI 2.43 to 5.47)

Summary

INTRODUCTION

Seasonality, a periodic surge in disease incidence corresponding to seasons or other stereotyped calendar periods, is characteristic of many infectious diseases of public health importance [24]. (b) enhanced accuracy of surveillance systems, (c) improved ability to predict epidemics and pandemics, and (d) better understanding of the long-term implications of global climate change for infectious disease control The latter three benefits are discussed while understanding of host and pathogen factors is described below. The potential utility of such systems is enhanced in the face of marked and ongoing global climate change; global warming may change the reproductive capacity of pathogens and vectors, alter the survival of pathogens in the physical environment, alter patterns of water use and availability, and increase the likelihood of extreme weather events All these factors could have a significant impact on the incidence and seasonal patterns of infectious disease occurrence [39, 50]

METHODS

CONCLUSION AND FUTURE DIRECTIONS

C-2 Fisman

10–35 N 10 N–10 S

Findings

C-4 Fisman