The only effective treatment for severe snakebite from a potentially deadly snake is anti-venom. Using it is not easy and it has its disadvantages, but in the right hands, and at the right time, it is life saving.
Yet people often have a poor understanding of how anti-venom works and there are many myths about it killing more people than the snake venom itself, not to mention numerous “miracle cures” including antihistamine, cortisone and Vitamin C.
Anti-venom for snakebite was first used in SA back in 1886, and local production started in Pietermaritzburg in 1901, but in small quantities, with most of the it still being imported from the Pasteur Institute in Paris, France. In those days one could purchase 10ml of cobra or mamba anti-venom from FW FitzSimons, director of the Port Elizabeth Museum.
In 1928, the SA Institute for Medical Research (SAIMR) started producing anti-venom, which was initially limited to Cape cobra and puff adder venom, but Gaboon adder venom was included in the manufacturing process in 1938. Around that time the first monovalent boomslang anti-venom was also developed.
Rinkhals venom was then added, followed by the production of different mamba anti-venoms in the 1950s and 1960s. In 1971 the venom of the forest cobra, Mozambique spitting cobra and snouted cobra were included to produce the polyvalent anti-venom that is still manufactured today.
Anti-venom is raised in a variety of animals including sheep, donkeys and camels, but in SA we use horses. A horse is either “hyper immunised” with a single snake venom (boomslang anti-venom) or against venoms of a variety of snake species (polyvalent anti-venom). This is done over an extended period, during which small quantities of venom are injected into the animal and increased over time as it builds up immunity.
Once the horse is immunised, plasma is collected from it. The plasma then goes through a process to remove proteins, pyrogens and microbes. The polyvalent anti-venom is captured in 10ml glass vials, costs in the region of R1000 a vial. It lasts for three years if stored in a refrigerator.
Anti-venom is now produced by the SA Venom Producers in Sandringham, Johannesburg. The polyvalent anti-venom covers the puff adder, Gaboon adder, rinkhals, green mamba, Jameson’s mamba, black mamba, Cape cobra, forest cobra, snouted cobra and Mozambique spitting cobra.
Even so, few snakebite victims are treated with anti-venom (less than 20 % of those hospitalised after a snakebite) because it is scarce and expensive, and can have disastrous side effects. The biggest danger is an acute allergic reaction (anaphylaxis) or serum sickness that can affect the patient’s immune system several days after treatment.
Snakebite victims are not automatically injected with anti-venom as most of them don’t experience symptoms severe enough to justify its use. Most snakes have full control over their venom glands and are quite reluctant to waste their venom on humans. They often give “dry” bites producing no symptoms of envenomation, or the snake might inject a little bit of venom that will cause discomfort or some symptoms, but nothing serious. In such cases, patients are usually hospitalised for a day, carefully monitored and then sent home.
Anti-venom should only be used in a hospital environment and when absolutely necessary. Patients will already be on a drip and the anti-venom is always administered intravenously, although intraosseous administration may be a consideration if veins prove difficult to find.
Most doctors will start with an initial dosage of six to 10 vials and in a recent severe mamba bite the victim received more than 30 vials before recovering.
As already mentioned, some snakebite victims quickly have an allergic reaction to anti-venom and this happens in more than 40% of cases. Some of those victims go into anaphylactic shock, which is a life-threatening medical condition and must be treated with adrenaline. This has to do with the fact that our anti-venom is made from horse blood and the allergy is basically an allergy to horses. Additional processes in the manufacturing of the polyvalent anti-venom could also reduce the incidence of anaphylaxis.
Anti-venom should only be used if there is a threat to life and limb, and only by a doctor in a hospital environment. It is highly effective and the sooner it is administered, the better.
In neurotoxic bites (mambas and most cobras) the venom may soon affect breathing. These are the dangerous bites that lead to most fatalities, whereas cytotoxic bites (puff adder and spitting cobra) often result in swelling, blistering and necrosis.
The sooner the anti-venom is administered the better the chances of preventing necrosis or reducing its extent.
It is a popular myth that more people die from the anti-venom than from the snake venom itself, but anaphylaxis is common and manageable if dealt with urgently and in the right manner. – Johan Marais