Epidemiology and Infection

Seasonality in six enterically transmitted diseases and ambient temperature

E. N. NAUMOVA a1c1, J. S. JAGAI a1, B. MATYAS a2, A. DeMARIA Jr. a2, I. B. MacNEILL a3 and J. K. GRIFFITHS a1
a1 Tufts University School of Medicine, Boston, MA, USA
a2 Massachusetts Department of Public Health, Boston, MA, USA
a3 University of Western Ontario, London, Canada

Article author query
naumova en   [PubMed][Google Scholar] 
jagai js   [PubMed][Google Scholar] 
matyas b   [PubMed][Google Scholar] 
demaria a   [PubMed][Google Scholar] 
macneill ib   [PubMed][Google Scholar] 
griffiths jk   [PubMed][Google Scholar] 


We propose an analytical and conceptual framework for a systematic and comprehensive assessment of disease seasonality to detect changes and to quantify and compare temporal patterns. To demonstrate the proposed technique, we examined seasonal patterns of six enterically transmitted reportable diseases (EDs) in Massachusetts collected over a 10-year period (1992–2001). We quantified the timing and intensity of seasonal peaks of ED incidence and examined the synchronization in timing of these peaks with respect to ambient temperature. All EDs, except hepatitis A, exhibited well-defined seasonal patterns which clustered into two groups. The peak in daily incidence of Campylobacter and Salmonella closely followed the peak in ambient temperature with the lag of 2–14 days. Cryptosporidium, Shigella, and Giardia exhibited significant delays relative to the peak in temperature (~40 days, P<0·02). The proposed approach provides a detailed quantification of seasonality that enabled us to detect significant differences in the seasonal peaks of enteric infections which would have been lost in an analysis using monthly or weekly cumulative information. This highly relevant to disease surveillance approach can be used to generate and test hypotheses related to disease seasonality and potential routes of transmission with respect to environmental factors.

(Accepted April 3 2006)
(Published Online June 19 2006)

c1 Department of Public Health and Family Medicine, Tufts University School of Medicine, 136 Harrison Ave, Boston, MA 02111, USA. (Email: elena.naumova@tufts.edu)