Epidemiological trends and seasonal dynamics of tuberculosis in Southeastern Turkey

Tuberculosis (TB) is an important public health issue. Determining TB trend and seasonal variability provides useful information for designing treatment strategies and control programs.

The present study attempts to investigate the epidemiological trend and the seasonal variations.

TB data containing 2450 cases were collected over a period of seven years in the province of Diyarbakir in southeast Turkey. Trend function and seasonal variability were investigated by statistical curve fitting, surface fitting, and autoregressive time series analysis.

The study revealed a gradually decreasing trend in the number of TB cases over a period of seven years. Total TB incidence had seasonal variations (P = 0.04); there was a greater number of TB cases between April and July, with a peak in June. There were significant monthly seasonal variations with June peaks among females (P < 0.001), in patients in the age groups of 0-15 (P < 0.001) and 36-45 years (P < 0.001), in new cases (P < 0.001) and in the patients with pulmonary TB (P = 0.01). The extra-pulmonary TB cases peak in May (P = 0.01). Pulmonary TB and TB patients in the 36-45 age group had summer peak, while the other groups peaked at spring.

Spring and summer peaks detected in total TB cases and in many subgroups indicate that multicenter and comprehensive clinical studies are needed to explain these variations.