The radiologic perspective of pulmonary tuberculosis seasonality in south-south Nigeria

Background: The periodic variation in the occurrence of disease within a calendar period is relatively common among many diseases, especially infectious diseases like tuberculosis (TB). Objective: The study is to radiologically evaluate the seasonality of pulmonary tuberculosis in our environment. Materials and Method: The study was a descriptive cross-sectional study over a period of 6 years (2017-2022) with one thousand, three hundred and fifty (1350) chest radiographs diagnosed of pulmonary tuberculosis. The chest radiographs were reviewed by three Radiologists with certification from the Faculty of Radiology of the West African College of Surgeons or the National Postgraduate Medical College of Nigeria. The data was analyzed descriptively using the statistical package for social science, SPSS version 23.0. Result: The monthly time series distribution of the radiologic diagnosis of pulmonary tuberculosis showed the lowest occurrences in the year 2020. The monthly average Seasonal Index of the radiologic occurrence of pulmonary TB shows that the months of June (1.29), July (1.95), and August (2.09) demonstrated the highest average seasonal index. The monthly averages from January to December over the 6 years of the study showed the highest occurrences in the month of August, and the lowest occurrences in the month of October. Conclusion: Although there were inconsistencies in the monthly pattern over the six year period, the highest incidence was in the month of August, followed by the month of July. Thus the study concludes that there exist seasonal variations in the radiologic diagnosis of pulmonary tuberculosis.