Remedy for dangerous cobra bites discovered
Bisses from Cobras Kill Thousands Every Year and Cause Permanent Damages Through Necrotic Tissue at the Bite Site
Cobra bites kill approximately 138,000 people worldwide every year, mostly in Africa and Asia, according to a group writing in the journal "Science Translational Medicine". An additional 400,000 people suffer permanent damages, such as loss of vision or amputations, due to local tissue death caused by the venom. "Snake bites are the deadliest of all neglected tropical diseases (NTDs), and this burden falls mainly on rural communities in countries with medium and low income", it continues.
The World Health Organization (WHO) aims to halve the health consequences of such bites by 2030. This study could potentially contribute to this ambitious goal, as the researchers initially focused on the speckled cobras, specifically the African speckled cobra (Naja nigricollis) and the red speckled cobra (Naja pallida).
Venom is Sprayed Over Several Meters
These species inhabit large parts of Africa south of the Sahara and can spray their venom over several meters. However, bites from the species discussed in the study are generally more dangerous. In general, snake venoms are cocktails of various toxins, with those of cobras primarily consisting of certain forms of the enzyme Phospholipase A2 (PLA2) and the three-finger toxins (3FTx), which also occur in the venoms of many other venomous snakes.
Antivenoms for a specific snake venom are currently produced by injecting a horse with the venom of a particular species and then isolating the antibodies from its blood. This outdated method is labor-intensive: The preparations must be heated, they are injected intravenously, the side effects can be severe, and the success rate is modest - not to mention the significant animal suffering involved.
Moreover, antivenoms do not help against the local effects on the tissue around the bite site. The current study focused on this aspect. Through genetic analyses, the research group identified which human genes are required for the local effect of the cell toxins. It turns out that cobratoxins bind to enzymes that are needed for the formation of similar molecules called Heparan and Heparin. Heparan is a molecule on the cell surface, while Heparin is produced by the immune system.
Neutralization of Cell Toxins
The researchers then searched for small molecules that could block the binding of cobratoxins to these enzymes. They identified a group of compounds called heparinoids, which include the clinically approved low-molecular-weight heparin Tinzaparin. In tests on cells and mice, these heparinoids neutralized the toxins of various cobra species to a large extent.
This is a significant advancement, as snake bites predominantly occur in rural areas and these medications do not need to be refrigerated, emphasized the research team led by Tian Du and Greg Neely from the University of Sydney. However, targeted studies in humans are still pending.
The study found that administered heparinoids bind to toxins and can neutralize them. This was not only the case for the studied cobras, but also for the toxins of Asian species of the Naja genus, such as the Monocled Cobra (Naja kaouthia), the Chinese Cobra (Naja atra), and the South Asian Cobra (Naja naja). However, heparinoids had no effect on the toxins of the West African Sand Viper (Echis ocellatus) and the Puff Adder (Bitis arietans).
"Our discovery could drastically reduce the terrible injuries caused by cell death following cobra bites and also inhibit the toxic effect, thereby increasing survival rates," quoted study leader Neely in a statement from his university. The first author Du added: "Heparin is expensive, common, and listed as essential medicine by the WHO. Following successful clinical studies, it could be quickly approved and become an affordable, safe, and effective antidote for cobra bites."
Despite the threats posed by snakes like cobras, education and awareness about their behaviors and venom can significantly reduce the number of fatalities and permanent damages. For instance, understanding the importance of avoiding these animals and seeking immediate medical attention after a bite can save lives and limbs.
Unfortunately, cobra bites remain a significant cause of death and disability, particularly in regions with limited resources and access to modern medical care. Therefore, the development of more effective and affordable antidotes, such as the use of heparinoids discovered in this study, could be a game-changer in combating this neglected tropical disease.
