Ambient temperature and notified Campylobacter in Israel; a time series analysis

Abstract

Background: Campylobacter infection poses a serious public health problem worldwide. Since the incidence varies between seasons, it is expected to be influenced by global climate changes. Aim: We studied the relationship between ambient temperature and weekly notified Campylobacter infections, using time-series analysis. Methods: Data on 29762 laboratory-confirmed cases of Campylobacter for the period 1999-2010 in the Jewish population were obtained from the Campylobacter Reference Center.Mean temperature and relative humidity for each week were calculated based on the airport monitoring station records. We used piecewise (two-segment) linear Poisson regressions, to estimate the association between weekly cases ofCampylobacterand average temperature value of lags 0-9 weeks. The effect of temperature was adjusted for seasonality, linear long term trends, holiday's indicator and relative humidity. Results: We found a J-shape relationship between temperature and Campylobacter cases. For the whole population, the percent increase in cases for 10C, below and above a threshold of 250C, was 3.5%(95%CI:1-6%) and 12%(95%CI:7-17%), respectively. The thresholds and the exposure-response curves varied between 3 age groups: 0-2y (28% of cases), 2.1-10y (25%) and 10.1+y (47%). For young children (groups: 0-2y and 2.1-10y) the curve was positive below and constant above the threshold; for ages 0-2y the percent increase in cases for 10C below a threshold of 210C was 7.7%(95%CI:4-11%), and for ages 2.1-10y it was 7.2%(95%CI:2-12%) below a threshold of 190C. For ages 10+y, the exposure-response curve was constant below and positive above the threshold; the percent increase in cases for 10C above a threshold of 24.50C was 15%(95%CI:8-22%). Conclusion: Our findings indicate that higher temperatures throughout the year are important and further intervention and education on food-handling behavior is needed. The difference in the age-related curves should be further explored.