Seasonal Patterns of Invasive Pneumococcal Disease

• Main Authors: Scott F. Dowell, Cynthia G. Whitney, Carolyn Wright, Charles E. Rose, Anne Schuchat
• Format: Article
• Language: English
• Published: Centers for Disease Control and Prevention 2003-05-01
• Series: Emerging Infectious Diseases
• Subjects: child; communicable disease; infection; photoperiod; pneumonia; research
• Online Access: https://wwwnc.cdc.gov/eid/article/9/5/02-0556_article
• ISSN: 1080-6040; 1080-6059

Pneumococcal infections increase each winter, a phenomenon that has not been well explained. We conducted population-based active surveillance for all cases of invasive pneumococcal disease in seven states; plotted annualized weekly rates by geographic location, age, and latitude; and assessed correlations by time-series analysis. In all geographic areas, invasive pneumococcal disease exhibited a distinct winter seasonality, including an increase among children in the fall preceding that for adults and a sharp spike in incidence among adults each year between December 24 and January 7. Pneumococcal disease correlated inversely with temperature (r –0.82 with a 1-week lag; p<0.0001), but paradoxically the coldest states had the lowest rates, and no threshold temperature could be identified. The pattern of disease correlated directly with the sinusoidal variations in photoperiod (r +0.85 with a 5-week lag; p<0.0001). Seemingly unrelated seasonal phenomena were also somewhat correlated. The reproducible seasonal patterns in varied geographic locations are consistent with the hypothesis that nationwide seasonal changes such as photoperiod-dependent variation in host susceptibility may underlie pneumococcal seasonality, but caution is indicated in assigning causality as a result of such correlations.