Seasonal Variation in Incidence and Severity of Dog Bites in a Union Territory of Northern India

Abstract

Introduction: Dog bites pose a serious but underestimated public health problem in developing countries like India as it causes millions of injuries and thousands of deaths among its sufferers due to risk of rabies transmission. Studying their seasonal pattern and variations would help in understanding their determinants and guide in formulating policies to contain this problem and eventually help in achieving elimination of rabies. Aim: To study the seasonal pattern and variations in incidence of dog bites and its association with severity in union territory of Northern India. Materials and Methods: A retrospective study was carried out at an Anti-Rabies Clinic (ARC) providing pre and post-exposure prophylaxis for rabies in Union Territory of Chandigarh, Northern India. All the cases of dog bite registered at the clinic for receiving post-exposure prophylaxis during the time period of 1st January to 31st December 2015 were examined from records and classified across the seasons according to timing of the bite to look for seasonal pattern and variation. Categories of all the dog bites registered as per WHO classification (Category II and III) of bite severity were also extracted from the records and were tabulated across the seasons. The severity of the dog bites was then correlated with the seasonality. One-Way analysis of Variance (ANOVA) was applied for comparing mean number of dog bites per month across the seasons. The chi-square test was applied to determine the statistical significance between the dog bite severity across the seasons. Results: A total of 853 cases of dog bite were registered at the clinic for post-exposure prophylaxis during the reference period. Mean number of dog bite cases per month were recorded highest in the spring season (90.0±16.9) followed by winters (82.5±13.0), the difference across the seasons being statistically significant (F value=5.26, p=0.02). Severity wise too, Category III bites were reported significantly more during spring (57.7%) and winter seasons (65.2%) as compared to summer and autumn seasons (c2=12.87, p=0.005). Conclusion: The present study provides the evidence that dog bites in a union territory of Northern India have wider seasonal variation. A significantly higher number of cases were observed in spring and winter seasons compared to other seasons which require further investigations.

Keywords

• anti-rabies clinic
• post-exposure prophylaxis
• seasonality
• world health organisation