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Objective: To define the level of alarm threshold for pertussisaberrations and to detect the aberrations of the reported suspectedcases of pertussis from the Mazandaran province in the north ofIran.Methods: The included cases were composed of the suspectedpertussis patients who came from Mazandaran province andregistered in the Center for Disease Control and Prevention from20 March 2012 to 20 March 2018. A discrete wavelet transformbasedmethod was used to detect the aberrations. All analyseswere performed using MATLAB Software version 2018a andExcel 2010.Results: A total of 1162 cases were recruited in the study,including 545 (46.90％) males and 617 (53.10％) females, withmedian age of 1.47 (0.22-9.56) years. The median age of maleswas 1.18 (0.21-8.24) years, while that of females was 1.82 (0.21-10.75) years. Concing the level of the alarm threshold, it was1.28 case/d when k=2, while it was 1.34 case/d when k=3. Thetotal detected aberration days were 123 d and 57 d by consideringk=2 and 3, respectively. The most defined alarm threshold wasrelated to spring (>2 cases/d) and summer (>1 case/d), respectively.Conclusions: The sensitivity of the surveillance system issubjected to a different time. Thus, determining the level of alarmthreshold periodically using different methods is recommended.