Singapore is home to two species of cobra: the king cobra and black spitting cobra (pictured). ST
SINGAPORE: When a snake sinks its fangs into the flesh of its prey, toxins in its venom can destroy the victim’s tissue almost instantly.
Currently, the common treatment for snake bites is an anti-venom delivered to the bloodstream through an intravenous drip. But this does not prevent the venom from creating lesions in skin tissues, which can cause permanent limb damage or amputation.
Treatment is also expensive and requires patients to be at the hospital, which could be hours to days after the bite – often too late for the anti-venom to work.
Scientists from the University of Sydney and Liverpool School of Tropical Medicine have, however, found a cheaper, more effective and more accessible antidote for cobra venom – heparin, a common blood thinner.
Heparin works by binding to the venom’s toxins, preventing them from destroying cells. On mice, heparin also reduced the size of venom-induced lesions if it is injected a few minutes after the venom.
To see which human genes are targeted by snake venom, the research team used gene-editing tool Crispr (clustered regularly interspaced short palindromic repeats), a technology to selectively modify the DNA of living organisms.
They found that the venom’s toxins attach themselves to a sugar known as heparan sulphate, so by editing out the genes that produce heparan sulphates, cells became more resilient to venom.
Heparins, hence, act as “decoys”, distracting the venomous toxins.
“Our discovery could drastically reduce the terrible injuries from necrosis caused by cobra bites – and it might also slow the venom, which could improve survival rates,” said Professor Greg Neely of the University of Sydney, corresponding author of the study.
As heparin is already approved and sold in pharmacies, it can be useful in rural or remote communities where hospitals are more scarce. In Singapore, heparin is a prescription-only drug that is likely available only at the hospital, said a spokesperson for private healthcare provider IHH Healthcare Singapore.
“People could go to the nearest pharmacy to get an injection,” said Professor Nicholas Casewell, head of the Centre for Snakebite Research and Interventions at Liverpool School of Tropical Medicine.
The downside? It can be used only to treat bites of certain snake species. While highly effective against cobra venom, heparin is entirely useless against, say, viper venom, which contains a different type of toxin.
While snakes are not common in Singapore, there are two species of cobra which make their home here: the king cobra and black spitting cobra. While they are highly venomous, they are also generally shy creatures which try to slither away from humans, the National Parks Board told The Straits Times.
When threatened, however, cobras can stand erect, expand their hood, hiss loudly and may attack. The black spitting cobra may also spit venom.
Do not try sucking out the venom of a cobra bite, the Changi General Hospital (CGH) warned on its website. There is no scientifically proven benefit, and it could even increase the possibility of infection.
Instead, the person should seek immediate medical assistance and call an ambulance.
It is best to stay calm, as slowing down the heart rate can slow the absorption of the venom into the bloodstream, said CGH.
Noting that heparin cannot completely replace anti-venoms to prevent death from snake bites, Dr Shirin Ahmadi, researcher of skin cell death, said: “It’s something that’s easy to use in the field and buys us a few hours until they (patients) get to the hospital.”
Clinical trials are under way to test heparin’s efficacy against the venom of other snake species.
“After successful human trials, it could be rolled out relatively quickly to become a cheap, safe and effective drug for treating cobra bites,” said lead author Tian Du, a PhD candidate at the University of Sydney. - The Straits Times/ANN
