Abstract
Introduction: Determining the temporal variationts and seasonal pattern of disease can help in promoting disease control and management program. Although seasonal variation in pulmonary tuberculosis (PTB) incidence has been described in many countries, it remains unknown in Tunisia.
The objective of the present study is to determinate seasonal variability of PTB in Tunisia.
Materials and methods: A time series study was conducted including pulmonary tuberculosis cases diagnosed in pulmonary departement of Rabta hospital from Junuary 2011 to December 2013. The aggregated number of monthly and seasonal PTB cases was obtained by adding the daily counts. We obtained also data of mean daily temperature from the Tunisian Meteoreological Agency.
Results: A total of 251 cases of active PTB were reported during this time. Seventy-seven percent of the patients were males. The peak of PTB was mainly in spring (36%) and trough in autumn (17%). The highest number of cases was registred in April, Mars and May with respectively 12.5%, 12% and 11.5% cases. There was no difference in season amplitude between males and females. Old peopole (>65ans) are more affected by seasonality (41.2% in winter). Relapse cases are more frequent in April (35%).
Conclusion: PTB is a seasonal disease in Tunisia. The peak and the through of PTB actually are in spring and automn. We suggest that acquiring tuberculosis in spring is due to recurrent respiratory infections, influenza, immunodeficiency and also living in confined spaces in winter , and after passing the pre-clinical stage the diagnosis of tuberculosis occurs in spring.
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