Habu bites are nonuniformly distributed in the Okinawa Island and the surrounding isolated islands. Mamushi bites were more distributed in southern part of Japan, and temperature was presumed to have an important influence on the distribution. Overall, the incidence of mamushi bites was estimated to be 1.67 bites/100,000 persons/6 months during July–December. With regard to mamushi bites, we have described the number of bites, the coverage rate of acute care beds and the population, and estimated the incidence of mamushi bites in each region, corresponding to latitudes of 30–34, 34–38, 38–42, and 42–46°N ( Table 1).
Three (0.2%) deaths were identified all were elderly (age range = 79–86 years) women with mamushi bites.Īddresses of 404 hospitals were geocoded, and locations were displayed on a map of Japan and were coupled with information on average annual temperature and population census data by using ArcGIS version 9.3.1 (Environmental Systems Research Institute Inc., Redlands, CA) ( Figure 1). With regard to complications induced by snake bites, 31 (1.9%) had diagnosis of compartment syndrome requiring fasciotomy, 77 (4.6%) cases had hypovolemic shock, 55 (3.3%) had acute kidney injury, and 29 (1.7%) had disseminated intravascular coagulations. Overall, 62.6% were males, and the mean ± SD age was 60.1 ± 20.1 years. The numbers of cases were 393, 575, 415, 234, 42, and 11 in July, August, September, October, November, and December, respectively. We identified 1670 snake bites (1,610 mamushi bites and 60 habu bites) from 404 hospitals (962 in 2007 and 708 in 2008). We obtained data for patients with a diagnosis of snake bite (International Classification of Diseases, 10th Revision code, T63.0) from 5.9 million inpatients during July 1–December 31 in 20. 11 The database includes location of hospitals patients' age and sex diagnoses recorded with the International Classification of Diseases, 10th Revision codes procedures drugs and devices used and lengths of stay and inhospital mortality rates. Data are compiled during July 1–December 31 every year by the DPC Research Group, which is funded by the Ministry of Health, Labor and Welfare, Japan.
The DPC hospitals cover approximately 38% of all the acute care beds in Japan. The DPC database is a discharge abstract and administrative claims data. We verified the incidence and geographic distribution of snake bites in Japan by using a currently available, nationally representative, hospital-based clinical database the Japanese Diagnosis Procedure Combination (DPC) inpatient database. 3 The situation is worse in Japan no national surveillance system is present, and the incidence of snake bites remains obscure. For instance, the American Association of Poison Control Centers reports annual statistics of snake bites in the United States, 10 but many snake bites go unreported because reporting is not mandatory and some treating physicians do not consult with a poison-control center. Surveillance systems on snake bites are not well established even in developed nations. 1 However, few reliable data on the accurate incidence and associated mortality are available, and the public health burden attributable to snake bites remains unclear. Presumably, snakes worldwide envenom hundreds of thousands of persons and kill or injure tens of thousands every year. Habu bites occur on Okinawa Island and the surrounding isolated islands (24–29°N), a region inhabited by 1.5 million persons.
Mamushi bites occur in areas between 30°N and 46°N. Mamushi ( Gloydius blomhoffii) 5, 6 and habu ( Protobothrops flavoviridis) 7 – 9 are two of the major venomous snakes in Japan both belong to the sub-family Crotalinae (pit vipers). Human-inhabited areas are located between 24°N and 46°N, which ranges from a subtropical zone to a temperate zone. 4 Japan has an area of approximately 378,000 km 2 and a population of approximately 127 million. 3 Venomous snakes are widely distributed in almost all countries between latitudes 50°N and 50°S. Snake bites remain a devastating, life-threatening, environmental hazard not only in tropical developing nations 1, 2 but also in developed nations.