Sunday, August 5, 2007

Epidemiology & The Risk of Snakebite

Your risk of being bitten be a snake is small, and so too is your risk of dying if bitten. Although there are an estimated 45,000 bites by all snakes in the United States each year, only about 6680 persons are treated for snake venom poisoning. However, it can be expected that at least 1000 additional bites by venomous snakes occur each year and that they are either not treated or go unreported. During the past five years, the number of deaths from snakebite in the United States has ranged between nine and 14. Most of the deaths occurred in children, in the elderly, in untreated, mistreated, or undertreated cases, in cases complicated by other serious disease states, or in members of religious sects who handle serpents as part of their worship exercises and refuse medical treatment. Almost all reported deaths have been attributed to rattlesnakes. In addition,"25 percent of all pit viper bites do not result in envenomation and another 15% are so trivial, they require only local cleansing and tetanus prophylaxis."

Approximately 75 percent of all snakebites occur in people aged between 19 and 30 years, 1 percent to 2 percent occur in women, and less than 1 percent occur in blacks. Approximately 40 percent of all snakebites occur in people who are handling or playing with snakes, and 40 percent of all people bitten had a blood alcohol level of greater than 0.1 percent. Sixty-five percent of snakebites occur on the hand or fingers, 24 percent on the foot or ankle, and 11 percent elsewhere. One case was reported of a snakebite on the glans penis.

So it seems that getting drunk and messing about snakes is a big cause of getting bitten. It also seems that male yahooism is a precursor to snake toxin poisoning. Women are unlikely to get themselves bitten, and if they do get bitten, it is unlikely that they got that way by doing something stupid. Here is some more interesting data on that point from Curry et al. in Annals of Emergency Medicine 1989 18(6):658-63:

A recent study reviewed medical records of 85 consecutive snakebite victims cared for at a single medical center to determine legitimacy of snakebites. A bite was considered illegitimate if, before being bitten, the victim recognized an encounter with a snake but did not attempt to move away from the snake. A legitimate bite was said to have occurred if a person was bitten before an encounter with a snake was recognized or was bitten while attempting to move away from a snake. The study group was made up of 75 male (87.2 percent) and 11 female (12.8 percent) victims. Seventy-four percent were 18 to 50 years old, and 15 percent had been bitten previously. Only 43.4 percent of all bites were considered legitimate, and pet (captive) snakes accounted for almost one third of all illegitimate bites. The ingestion of alcoholic beverages was associated with 56.5 percent of illegitimate bites versus 16.7 percent of legitimate bites. While 74.4 percent of bites were to upper extremities, only 27 percent of upper extremity bites were legitimate. All bites to the lower extremities were legitimate. Of 14 individuals bitten by pet snakes, all were men and 64.3 percent were under the influence of alcohol at the time of the bite. In our patient population, the data suggest that a 16 percent reduction in rattlesnake bites would result if rattlesnakes were not kept as pets, and more than one half of all rattlesnake bites would be eliminated if persons simply would attempt to move away from a rattlesnake after an encounter is recognized.

It is worth noting that only one woman in Curry et al.'s study group received an illegitimate bite.

No comments:

Post a Comment

Leave me some feedback