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ASI Newsletter - April 2018

The Deadly Dozen
In South Africa we have a dozen snakes (out of a total of 121 different types) that are considered deadly. These are the mambas, cobras, Rinkhals, Puff Adder, Gaboon Adder, Boomslang and Twig Snake. There have been reports of deaths from the Berg Adder, Speckled Shield Cobra, Coral Shield Cobra and even the Many-horned Adder but most reports cannot be substantiated. Bites from very large Rhombic Night Adders and Stiletto Snakes could also be life-threatening, especially where small children are involved.

The Black Mamba (Dendroaspis polylepis) is undoubtedly one of the deadliest snakes in the world and accounts for around half of the dozen snakebite fatalities in South Africa every year. Its venom is potently neurotoxic and may soon affect breathing. Other symptoms include a metallic taste in the mouth, numbness of the lips, slurred speech, nausea and vomiting, ptosis and progressive weakness. Untreated bites may result in death within 3 – 16 hours but in exceptional cases people have died within 30 minutes. Despite popular belief the Black Mamba is far from aggressive and is very quick to avoid people, but if surprised or accidentally cornered it will not hesitate to strike and may do so more than once.

Black Mamba (Dendroaspis polylepis)

Like the Black Mamba, the Cape Cobra (Naja nivea) also has a potent neurotoxic venom and victims may experience problems with breathing in under 30 minutes, especially small children. Unlike the Black Mamba this snake stands its ground, is quick to hood and bites readily. It adapts quickly to urbanisation and is often found around informal dwellings. It is quite common in some areas and is often found in gardens. This snake varies in colour from near black to dark, medium or light brown, golden brown or orange to yellow or may be speckled. By the time victims are hospitalised they are often in a non-responsive state of paralysis and need to be ventilated.

Cape Cobra (Naja nivea)

The Mozambique Spitting Cobra (Naja mossambica) accounts for the majority of serious snakebites in South Africa. It is a common and abundant snake that is often found in gardens or even in houses or lodges where victims are often bitten while asleep. Victims often include small children or even babies and the bites are not as a result of people rolling onto snakes seeking heat in their beds but rather the snakes finding people asleep in the dark and mistaking them for a potential meal. Its venom is potently cytotoxic, causing severe pain, swelling, blistering and tissue damage. While fatalities are rare the extent of tissue damage may require reconstructive surgery. The early administration of sufficient polyvalent antivenom (10 vials or more) may reduce the extent of tissue damage but not always. This snake also spits its venom.

Mozambique Spitting Cobra (Naja mossambica)

The Puff Adder (Bitis arietans) is the most widely distributed of our deadly snakes and relies heavily on camouflage to avoid detection. It moves around mostly at night and will bite if stood on. This snake has massive fangs – reaching close on 2 cm in length – that deposit the snake’s destructive cytotoxic venom very deep into muscle. Like the Mozambique Spitting Cobra the venom of the Puff Adder causes pain, swelling, blistering and tissue damage but fatalities are rare. Interestingly enough recent research by Prof. Graham Alexander and his team at Wits University showed that Puff Adders in camouflage mode (which they are in most of their lives) will not bite even if accidentally stood on. The Puff Adder and Mozambique Spitting Cobra account for well over 90% of all serious snakebites in South Africa.

Puff Adder (Bitis arietans)

The Green Mamba (Dendroaspis angusticeps) has a limited distribution in South Africa and is found along the coast in KwaZulu-Natal usually within a few kilometres of the sea. In Zululand it may go as far as 20 km inland but does not occur in Mpumalanga, Swaziland or the KNP. This snake inhabits thick coastal forest and is quick to disappear into dense foliage when disturbed. Sadly many of the harmless green snakes of the genus Philothamnus are mistaken for the venomous Green Mamba and needlessly killed. Bites are few and far between and fatalities quite rare. The venom of the Green Mamba is both cytotoxic and neurotoxic and in recent bites there has been quite a bit of swelling. This is not a common snake but is found in suburban gardens from time to time.

Green Mamba (Dendroaspis angusticeps)

The Snouted Cobra (Naja annulifera), previously known as the Egyptian Cobra, is one of our largest cobras reaching 2.5 m in length. It is often found in fowl runs in search of food but bites from this snake are quite rare. Like most cobras its venom is a mixture between cytotoxins and neurotoxins, often resulting in tissue damage. While most individuals are light to medium yellowish-brown to dark purple in colour, some individuals are clearly banded and referred to as Banded Cobras.

Snouted Cobra (Naja annulifera) 

The Forest Cobra (Naja melanoleuca) occurs from Ballito in KZN northwards and just enters the KNP at Pafuri. It is an excellent climber and prefers dense vegetation where it can easily escape. It is also a large cobra, reportedly reaching 2.5 m in length. The Forest Cobra is by far the most placid of our cobras and rarely bites unless handled or stood on. This snake can be distinguished from other cobras in that the front half is a shiny mottled golden brown colour becoming very dark towards the tail. It lifts it head well off the ground when threatened and forms a narrow hood. The venom of the Forest Cobra is both cytotoxic and neurotoxic.

Forest Cobra (Naja melanolauca)

The Black Spitting Cobra (Naja nigricincta woodi) in habits dry riverbeds in Namaqualand but moves into rocky hills in the Northern Cape and southern Namibia. It is extremely shy and very quick to move off – bites are extremely rare. When cornered it spreads an impressive hood and spits effectively. Like all of our spitting snakes its venom is largely cytotoxic. The effectiveness of polyvalent antivenom against its venom is not well known as its venom is not used in the production of polyvalent antivenom.

Black Spitting Cobra (Naja nigricincta woodi) (Photo by: Dionne Miles) 

The Rinkhals (Hemachatus haemachatus) is largely a grassland species but is also found in fynbos in the Cape. It is a shy and elusive snake that often has a permanent home into which it will escape quickly if disturbed. If cornered it will lift as much as half of its body well off the ground, form a hood and spit while lunching forward. Dogs are often bitten while trying to kill a Rinkhals but bites on humans are rare. The venom of the Rinkhals is largely cytotoxic and the last fatal bite on a human was more than 40 years ago.  On the Highveld individuals are dark grey to black with two or three white bars across the chest but in KZN and the Cape provinces individuals have bars.

Rinkhals (Hemachatus haemachatus)

The Gaboon Adder (Bitis gabonica) occurs from Mtunzini in KZN northwards through Richards Bay, St. Lucia and Ndumu, living on the edges of thick coastal forest where it is seldom seen. Most individuals encountered are seen crossing roads at night. It is our largest adder and has the longest fangs of any snake in the world – close on 5 cm in length. Like the Puff Adder, the venom of this snake is potently cytotoxic causing severe pain, swelling, blisters and tissue damage. Bites from this snake are virtually unheard of – quite fortunate as it has a large venom yield.

Gaboon Adder (Bitis gabonica)

The Boomslang (Dispholidus typus) spends most of its life in trees and is extremely placid. Bites are rare and usually only when stood on or when a snake handler grabs one. Despite being back-fanged the Boomslang can open its mouth very wide and bite quite easily. In trees this snake poses no great threat and the chances of being bitten while walking under a tree are close on zero.  Having said that, there are one or two bites every year and one fatal bite in 2017. The venom of the Boomslang is potently haemotoxic with little or no symptoms for up to 20 hours or longer after a bite, then bleeding from the nose, mucous membranes and eventually internal bleeding. There is a highly effective monovalent Boomslang antivenom available.

Boomslang (Dispholids typus)

The Twig or Vine Snake (Thelotornis capensis), like the Boomslang, is a placid snake that rarely attempts to bite unless handled. It is usually found in trees and shrubs, quite close to the ground and is perfectly camouflaged. When threatened, it will inflate the neck region and eventually most of the body (the Boomslang does the same), and then strike readily. Bites are virtually unheard of and usually on snake handlers. Twig snake venom is potently haemotoxic, like that of the Boomslang, and while a few fatal bites have been reported from further north there have been no fatal bites in South Africa. There is no antivenom for the venom of this snake.

Twig Snake (Thelotornis capensis)