Environmental factors associated with the prevalence of animal bites or stings in patients admitted to an emergency department

Background: Environmental factors may affect the prevalence of different animal bites; however, this area has not been well studied. The aim of this study was to report in detail on the categories of animals involved in causing bites or stings, patient characteristics, outcomes, and associated environmental factors. Methods: This prospective study involved patients visiting an emergency department for animal bites or stings from January 2007 to December 2008. Patient demographics, type and severity of injuries, outcomes, and types of offensive animals were recorded on a predefined database. Environmental factors, including season, temperature, precipitation, and relative humidity, were collected. Analyses were undertaken to check the relationship between animal bite/sting injuries and environmental factors. Results: Mammalian bites (65.2%) were the most common, followed by insect stings (24.9%) and reptile bites (7.2%). Dogs (54.3%), bees (12.9%), and snakes (7.0%) were the three most common animals to attack. Most of the injuries were mild, superficial, and located on limbs. Only 5.3% of patients had moderate effects and 1.5% of patients had major effects in outcomes. Poor outcome-related factors included large size of wound (maximum length of wound > 3 cm; p=0.000), wound type (skin defect; p=0.000), and animal type (reptile bite; p=0.000). The season in which the most injuries occurred was summer for insects and autumn for reptiles. No significant trend was found for mammals and other animals. We found the highest precipitation and insect bites/stings in June (r=0.93, p < 0.001), and increased incidence of insect bites/stings in the hot months (r=0.83, p=0.001). We also found increased reptile bites in May to June and September to October, which may be associated with a significant change in precipitation (r=0.78, p=0.005). Conclusions: The most common animal bites seen in our emergency department are from mammals, especially dogs. Although most animal bites/stings were superficial and minor, there are risks of major effects on outcome in cases with large wounds or reptile bites. Environmental factors, including the season, temperature, and precipitation, were related to insect and reptile stings/bites. Copyright (C) 2012, Taiwan Society of Emergency Medicine. Published by Elsevier Taiwan LLC. All rights reserved.