|King Cobra (Ophiophagus hannah)|
Bites from venomous snakes are common in many parts of the world and a serious unresolved health problem to millions of people living in South and Southeast Asia, as well as Africa and Latin America. Although there are no reliable numbers at the global scale, it has been estimated that at least 421,000 cases of venom snakebites with up to 94,000 deaths occur worldwide each year. However, experts warn that these figures likely underestimate the real problem, which is believed to affect several million people bitten by venomous snakes annually and hundreds of thousands who die or survive disabled, suffering from amputation or deformed limbs as a result of unavailable or delayed treatment.
People bitten by snakes often do not seek treatment at a medical facility, and if they do, the vast majority don't take the snake with them although it is often killed. Of course they also can't identify the species that actually bit them. However, knowing the species of snake is critical to determining the best course of treatment. And even if the victims do everything right, the clinical personal does not necessarily have the expertise to identify the snake species.
Researchers from Thailand have now build a first DNA Barcode reference library for venomous snakes and one non-venomous snake (Python bivittatus bivittatus) found in Thailand. Based on their results they also developed species-specific multiplex PCR markers to allow for rapid delimitation of
eight groups of venomous snakes for which the Thai Red Cross keeps antivenom for clinical use. This assay could easily be applied to venom and saliva samples. If venom could be assigned to a particular species, doctors could quickly give anti-venom instead of waiting for clinical signs of poisoning, as it is current practice. This would also accelerate the transfer of patients to referral hospitals with intensive care units able to ensure adequate respiratory support. Such a test would be easy to administer in rural healthcare settings with limited resources.
This is a promising development in the search for an efficient means of examining snakebites, which could ensure the application of appropriate antivenom therapy. However, improvements in the sensitivity of markers, the limitation of locally restricted markers, and protocols for DNA isolation from a remnant swap are still required in order to produce an optimal and practical procedure for the delimitation of snake species.