To treat victims of snakebites, it's important to know which type of snake did the biting. Now, a new test looks at the tiny bits of snake DNA that are left in the fang marks on victims, to identify the species, a new study shows.
In the study, researchers collected 194 DNA samples from the bite sites on snakebite victims in Nepal. In 21 cases, the patients actually brought the dead snake that had bitten them to the treatment center, and the researchers were able to verify the source of the bite. In all of those cases, the results of the DNA test agreed with the dead-snake species identification conducted by independent experts.
"You need to know the species that bit your patient [in order to treat them]," said study co-author Ulrich Kuch, of the Department of Tropical Medicine and Public Health at the Goethe University Institute of Occupational, Social and Environmental Medicine in Germany, and the developer of the snake DNA identification test.
"Now, with the DNA-based test, we can substantially increase the number of patients for whom we can identify the snake species [responsible for the bite]," Kuch told Live Science.
Right now, the DNA test is too complex and time-consuming to be performed for every snakebite victim, said study co-author Francois Chappuis, chief of the division of tropical and humanitarian medicine at Geneva University Hospitals in Switzerland.
However, the test could be used as an epidemiological tool to help doctors determine which snake species most commonly bite people in different regions. [The World's 6 Deadliest Snakes]
"When people get bitten by snakes, they rarely come to treatment centers with the snakes" that bit them, so it is often not clear which snake has inflicted a bite, Chappuis said.
In the new study, the researchers found that 87 of the 194 bites were inflicted by venomous species. The spectacled cobra was responsible for 42 bites, and the common krait inflicted 22 bites.
The new DNA test may also help researchers develop faster diagnostic tests for snakebites, Kuch said. Indeed, the researchers are working on developing a blood test that would take only 20 minutes. Doctors could use this test to identify the source of a bite, and more efficiently decide on the best course of treatment, Kuch said.
For example, if krait venom were detected, doctors could quickly administer antivenom instead of waiting for clinical signs of envenomation,as they currently do, the researchers said.
In the study, the investigators also established a relationship between the type of snake that inflicted a bite and the symptoms that resulted from it. They found that krait bites happened more frequently at night and indoors, while victims were sleeping. They found that localized swelling tended to happen with cobra and pit-viper bites.
The World Health Organization currently lists snakebites as one of its 17 "neglected tropical diseases," which are the conditions that cause a significant number of deaths and illnesses but tend to get less attention from people in developed countries.
Snakebite envenomation "affects the poorest of the poor," who often live in regions where there is little awareness of the issue, Kuch said.
"Most people are unaware that snakebite is a very real and serious threat both to the health and economic vitality of rural communities throughout much of the developing world," Dr. Alan J. Magill, president of the American Society of Tropical Medicine and Hygiene, who was not involved in the study, said in a statement. "This innovative research may be enabling for the development of a point-of-care test to positively identify biting snakes."
The study was presented Tuesday (Nov. 4) at the American Society of Tropical Medicine and Hygiene's annual meeting in New Orleans. The results have not yet been published in a peer-reviewed journal.