Anti venom for snakebite
Antivenom for snakebite in South Africa is produced by the South African Vaccine Producers (SAVP), part of out National Health Laboratories which is a government institution. They are situated in Edenvale, Johannesburg and not Onderstepoort, as people often think.
For snakebite in South Africa they produce two antivenoms, a monovalent Boomslang antivenom that comes in 10 ml vials and costs R6,800 per vial. As Boomslang bites are extremely rare it is seldom used but when required, most victims receive two vials. It is a Schedule 4 drug and requires a script from a doctor in order to purchase it. A vial lasts three years in a refrigerator and each vial has a three year expiry date printed on it.
They also make a polyvalent antivenom that comes in 10 ml vials and costs R1,910 per vial. It also has a three year shelf life and must be refrigerated at all times. This product can be purchased from SAVP without a script.
The polyvalent antivenom is prepared using the venom of ten snake species – the Puff Adder, Gaboon Adder, Black Mamba, Green Mamba, Jameson’s Mamba, Cape Cobra, Forest Cobra, Snouted Cobra, Mozambique Spitting Cobra and the Rinkhals. In addition to these species there is evidence that there is cross-coverage and the polyvalent antivenom has been used for bites from other snakes like the Black-necked Spitting Cobra and the Black Spitting Cobra.
Depending on what snake is responsible for a bite and a variety of other factors, victims receive anything from 6-12 vials of polyvalent antivenom and in severe Black Mamba bites up to 40 vials have been used. The most important consideration in serious snakebites is to give sufficient antivenom sooner rather than later and it appears that in some bites like Mozambique Spitting Cobra bites the antivenom must be given within the first few hours after a bite (less than 6 hours) to effectively neutralise the snake venom and prevent severe necrosis.
SAVP produce antivenom by hyper immunising horses, a process that takes around nine months during which small quantities of snake venom are injected into horses, not enough to do harm the horse, but enough to trigger its immune systems. The amount of venom injected is gradually increased as the horse becomes more resistant to the venom. Snake venom is sourced from individuals and companies locally and elsewhere in Africa. Once immune, blood is drawn from the horse at two month intervals and the serum is removed from the blood, the latter is returned to the horse and the serum purified. It is bottled in 10 ml vials in liquid form.
The correct treatment for serious snakebite envenomation is antivenom provided it is administered for the right snakebite, early enough and in sufficient quantity. It is not a first aid treatment and should only be administered in a hospital environment by a medical doctor. Part of the reason for this is that nine out of ten snakebite victims do not require antivenom. Some victims also have an allergic reaction and for this reason antivenom should only be administered in a hospital environment where a medical team can cope with such reactions.
We are often asked which hospitals carry antivenom. There is no register of hospitals that do as a hospital can purchase antivenom today, use it tomorrow and not replace it. Hospitals in high risk snakebite areas tend to keep antivenom and those in low risk areas seldom do. Several hospitals also keep far too little antivenom for a single treatment. Bear in mind that snakebite deaths, in the short term, are largely because venom effects breathing and for that reason it is important to get the patient to the nearest hospital where he or she can be ventilated. Once stabilised they can establish whether they have antivenom or if the patient needs to be transferred to another centre. The disadvantage with cytotoxic bites (like Mozambique Spitting Cobra or Puff Adder bites) is that the longer it takes to administer antivenom, the more severe the subsequent tissue damage.
Source: African Snakebite Institute