Epidemiology of Snake, Spider and Scorpion Envenomation in Mashhad, Khorasan Razavi, Iran (2004-2011)

Backgrounds: Envenomation is common in Asia including Iran that induces morbidity and mortality. This study investigated the epidemiological characteristics of cases with snake, spider and scorpion bites. Methods: In this cross-sectional design, epidemiologic data of admitted cases to the Toxicology Department of Imam Reza Hospital of Mashhad, Iran were analyzed across a 7-yr period, from 2004 to 2011. SPSS was used for data analysis. Results: This study reports 686 admissions due to animal envenomation with an incidence rate of 2.9 per 100000. Mean (SD, min-max) age of admitted patients was 30 (19, 1-90) yr, and 471 (69%) were male. Snakebite (n, percentage, annual incidence) (299, 44%, 1.3 per 100000) and spider bite (188, 27%, 0.8 per 100000) and scorpion sting (126, 18.4%, 0.5 per 100000) were most frequent cases. Overall, case fatality rate was 0.09 per 100000 which were due to scorpion and unknown bite. No cases of snakebites died in this period. The highest age-specific incidence rate was 4.6 per 100000 and related to 10-20 yr of age. Conclusion: Animal envenomation is frequent in this area and a matter of health concern. While deaths related to snake bite are no longer reported-presumably due to using effective anti-venom - managing unknown and scorpion bites need to be addressed. Envenomation was not overtly an age-specific event in this province.