Most Snakebites Unexpected, Occurring Without Intentional Contact

October 3rd, 2016

WEST HARTFORD, CT – When a patient presents to the emergency department with a poisonous snakebite, emergency physicians might wonder how that occurred and whether the injury calls into question the patient’s judgment.

New research published in the journal Wilderness & Environmental Medicine provides some answers. An analysis of media reports about snakebites in the United States suggests that most are likely “legitimate,” i.e., occurring by surprise, without intentional contact, in a natural setting.

Previously, it was believed that the majority of snakebites occurred when humans were handling the reptiles in captivity or attempting to kill or move a wild snake.

Interestingly, University of Hartford researchers found that media coverage detailed victim circumstances better than current quantitative data.

"Examining media-reported snakebite accounts provides a novel way to assess snakebite patterns in the United States," explained co-investigator Stephan Bullard, PhD. "Clinical reports tend to contain minimal personal detail, but a great deal of information about the pathologic effects and treatment of snakebites. Media reports vary widely, but are generally human interest stories that extensively detail the victim's activities leading up to the bite and usually contain little information regarding medical implications of the bite."

For the study, researchers looked at 332 media-reported bites from 2011-2013 and found that 307 (92.4%) occurred under natural conditions, while only 25 bites happened in captive-care situations. Most, 67.9%, of the total bites were found to be legitimate, meaning the victim was unaware of the snake's presence. The others were labeled as “illegitimate” bites that resulted from the purposeful handling of the snake.

Results of the media review also indicate that men were much more likely to be bitten by a snake, accounting for 67.1% of the victims in the study. The results also suggest that the location of the bite on the body reliably indicates whether or not the bite was legitimate: Legitimate bites more frequently occurred on the lower extremities, and illegitimate bites occurred more often on the hands and fingers.

A slight majority of the victims, 54%, reported walking or hiking when bitten, and 40.2% were bitten when they placed a body part in an area they could not see, such as while gardening or reaching into a woodpile.

Most of the bites were from rattlesnakes and copperheads, with bites from cottonmouths and coral snakes much less common. The review also gave credence to a theory that snakes release more venom the more threatened they feel.

"Eight of the 10 fatalities resulted from intentional, extended interaction with the snake," co-investigator Dennis K. Wasko, PhD, said in an Elsevier Health Sciences press release. "Although this is a relatively small sample size, these patterns support previous findings that snakes assess threat risks and meter their venom accordingly. Startled snakes frequently at first inflict dry bites in which little or no venom is injected, whereas direct restraint or repeated contact induces a defensive release of more venom."

An estimated 8,000 snakebites occur annually in the United States, according to background information in the article.

"Future efforts should focus on determining more about the specific triggers of snakebites, especially under natural conditions,” Bullard said. “A comprehensive, nationwide database of human envenomation by snakes is also needed for future study.”