November 4, 2008

Snakebites Are A Growing Threat

In a new study, researchers defined new parameters for estimating the global effect of snakebites.

Poisoning incurred by snakebite is a serious threat to many residents of poorer, tropical and subtropical countries.

Researchers note that few attempts have been made to estimate the extent of their affect, due to "the lack of an objective and reproducible methodology." Therefore, experts developed a new method to estimate the disease burden caused by snakebites.

In a WHO-funded study, researchers analyzed data from 3,256 published articles on 68 countries. Countries were grouped into 21 distinct geographic regions that are as epidemiologically homogenous as possible.

If no data were available for a particular country, the lowest incidence rate within a neighboring country was used.

According to a conservative estimate, there are 421,000 cases of envenoming, or venom delivered through biting, each year and which lead to at least 20,000 deaths, researchers said.

However, the number could be much larger, they added.

"These figures may be as high as 1,841,000 envenomings and 94,000 deaths. Based on the fact that envenoming occurs in about one in every four snakebites, between 1.2 million and 5.5 million snakebites could occur annually," wrote the team led by Janaka de Silva at the University of Kelaniya in Sri Lanka.

Researchers found that the highest burden of morbidity and mortality from snakebites exists in South Asia, Southeast Asia, and sub-Saharan Africa.

India has the highest figures -- with 81,000 envenomings and 11,000 deaths each year, followed by Sri Lanka with 33,000 envenomings, Vietnam (30,000), Brazil (30,000), Mexico (28,000) and Nepal (20,000).

"Many victims do not seek hospital treatment and prefer traditional remedies. Some may die at home, with their deaths unrecorded," they wrote.

"Studies from rural Nigeria and Kenya have reported that only 8.5 percent and 27 percent of snakebite victims, respectively, sought hospital treatment."


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