ASI Newsletter 

Dangerous Scorpions of southern Africa

With around 150 described species of scorpions in southern Africa (and new species still being described) scorpion identification is no easy task.

All scorpions are venomous, however, stings from a number of species are mild and are not of medical importance. They may be painful for a few hours but are not potentially life-threatening.

There are several old and incorrect stories about scorpions and scorpion identification. One such story is that only black scorpions are dangerous. There is no rule of thumb for determining whether a scorpion is dangerous or not based on colour alone. Highly venomous scorpions come in a variety of colours ranging from black, brown, yellow, light brown, orange and a mixture of all of the above.

Another story is based on the size of the scorpion, with many people incorrectly telling us that smaller scorpions are far more venomous than larger scorpions. The size of a scorpion makes little difference as to how dangerous it is. A baby Thicktail Scorpion of a few centimetres long will deliver a painful and potentially dangerous sting compared to the mild prick delivered from a large (up to 20cm) Rock Scorpion.

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The main rule for identifying potentially dangerous scorpions is based on the size of their tail in relation to the size of their pincers: those with thick tails and small pincers being far more venomous than those with a thin tail and large pincers.

The genus Parabuthus (A) is known as our Thicktail Scorpions and some of them are considered potentially deadly in southern Africa. There are two species that are potentially life-threatening and the other species may deliver a painful sting. Note the ratio of small pincers to thick tail in Parabuthus.

Nomads (Hottentota sp.) and Pygmy-thicktails (Afrolychus sp.) are not represented on this chart as they are not commonly encountered in Southern Africa. These two genera are small scorpions and are not life-threatening but have a nasty venom that causes intense pain.

The genus Uroplectes (B) are known as Lesser-thicktails or bark scorpions. These are generally small scorpions of a couple of centimetres in length. They too have thick tails and small pincers and a sting from one of these may be very painful, although not life-threatening.

The Burrowers (C) and Creepers (D) are made up of three genera: Opistophthalmus (C) and Opisthacanthus and Cheloctonus (D). These genera have large pincers and medium to small tails. The pain from the sting of these scorpions can be compared to that of a bee sting. They can also pinch pretty hard with their large pincers.

The Plain Pygmy-thicktails in the genus Pseudolychus (E) are small scorpions that usually live in leaf litter and are commonly encountered in houses, especially in Gauteng. The sting burns for a few minutes and then fades away and is less than a wasp sting in pain.

Lastly, we get the Rock Scorpions (F) in the genus Hadogenes. These large scorpions often exceed 20cm in length and are gentle giants, their sting is barely noticeable. It is comparable to the thorns of an Acacia tree, where there is a slight tingling feeling and then becomes itchy. If the scorpion is upset however, those pincers give a good pinch!

The two potentially life-threatening species in southern Africa are:

The Rough Thicktail Scorpion (Parabuthus granulatus) is one of the largest scorpions in the region, reaching 18 cm in length with the tail extended. Individuals can be black in colour, dark brown or yellow, sometimes with lighter legs and a darker back segment.

It occupies karoo and bushveld habitat on the drier western side of the country, occurring in the Western Cape, Northern Cape, North-west and Limpopo in South Africa. It occurs throughout Namibia and Botswana, extending into western Zimbabwe. It has one of the largest distributions of the Thicktail Scorpions and overlaps with a number of other species. It is therefore often confused with the Cape and Transvaal Thicktail Scorpions.
This is the most venomous scorpion in southern Africa and accounts for a few fatalities every year. There is an effective antivenom for the sting of this species. On lab tests, this species is three times as venomous as the Transvaal Thicktail Scorpion (Müller et al. 2012). Bergman (1997) showed that of the ten Rough Thicktail Scorpion stings they examined, 30% were severe.

The Transvaal Thicktail Scorpion (Parabuthus transvaalicus) is a large scorpion in southern Africa reaching a length of around 15cm with the tail extended. It is dark brown to black in colour, often with lighter pincers. It occupies bushveld habitat and can be found under rocks, logs and other debris.

It often ventures into houses and can also be found under outdoor lights at night, hunting insects and other prey. It occurs from north of the Magaliesberg into Limpopo, Mpumalanga and the North West province and north into south-eastern Botswana and southern Zimbabwe as well as parts of Mozambique. It is often confused with the Rough Thick-tail Scorpion as their size and colour can be similar. The venom is medically important and antivenom is effective for stings. Excessive sweating and ptosis (drooping of the eyelids) are common symptoms of envenomation. Bergman (1997) showed that of the 184 Transvaal Thicktail Scorpion stings they examined, 10% were severe. In the recorded stings, deaths have occurred, taking between 12 hours and six days.

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The Cape Thicktail Scorpion (Parabuthus capensis) is a medium-sized scorpion of around 10cm with the tail extended. They are usually a pale orange or yellow in colour, often with a darker last segment of the tail. Pitch black individuals are common around Lambert’s Bay on the west coast.

This species is known from the Western and Northern Cape provinces, usually sheltering under rocks and logs. It is easily confused with the Rough Thicktail Scorpion and the Drab Thicktail Scorpion.

The venom of this species causes intense pain and generally isn’t considered life-threatening, although there is one unconfirmed death by this species mentioned in Müller et al. (2012). As far as we know, antivenom is not effective against the sting of this species.

Most southern African scorpions are not life-threatening to humans. Only the Thicktail Scorpions (Parabuthus sp.) are considered dangerous, and of the 22 species of Thicktail Scorpions, only two have accounted for confirmed human fatalities.

Most victims are stung on the foot between sundown and midnight. Most stings happen outside, although a number have been reported in houses, especially with the Transvaal Thicktail Scorpion and Lesser-thicktail scorpions, which often enter houses and may hide in bags or clothes (Müller, 2012). Scorpion stings are immediately painful. This pain may last from a few minutes to hours or even days depending on the species. Local paraesthesia (pins and needles) is often experienced. There is usually very little swelling and often the sting site is difficult to locate (Müller, 1993). In stings from Thicktails, hyperaesthesia (sensitivity of the skin) is often experienced with the nerves being hypersensitised. This results in the victim experiencing pain if the skin is touched or if ice is placed on the sting site. Victims also talk of a feeling of vibration of the skin similar to an electric current (Müller, 2012).

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The venom of the Thicktail Scorpions is a neurotoxic venom that affects potassium and sodium channels in the cells of the body. This may cause hyperexcitability of certain muscles and often results in jerks and twitches of the body as well as tremors and spasms of muscles, especially in the face. Children are often excessively restless. Other symptoms include extreme pain at the site of the sting that may spread throughout the body. Excess salivation, a slow heart rate, high blood pressure and gastric distension (enlargement of the stomach which may cause abdominal pain) is also noted. Muscle weakness often follows, and victims may struggle to walk, or walk as if they are drunk. Bulbar paralysis causes the victim to struggle to swallow, reduces the gag reflex and may restrict the ability to pronounce words. The final symptom, and most dangerous, is difficulty with breathing which may lead to respiratory failure. In stings to children where the species is not known, it is advisable to monitor the child for at least 12 hours (Müller, 1993; Müller, 2012).

Symptoms are directly related to the size of the victim, the amount of venom injected and the physical health of the victim. Unfortunately, children and the elderly are often at a higher risk and may show symptoms rapidly (within one to two hours), whereas in healthy adults, symptoms may be delayed for up to 8 hours (Müller, 1993). Pain killers are not recommended as they are often ineffective against scorpion venom and may reduce the breathing rate of the victim (Müller, 1993). In hospitals, they may inject local anaesthetic around the sting site to help with pain control (Müller, 2012). In severe cases, 10 - 20 ml of SAVP Scorpion antivenom is delivered via an intravenous drip. An additional 10 ml is advisable if there are no improvements after six hours. Respiratory support is vital during these times. Patients who receive antivenom and treatment in a hospital generally make a full recovery within a few days. Patients who do not receive antivenom may take up to seven days to recover (Bergman, 1997).

In the event of a sting from any of the above three species:

• Try get a photo of the scorpion (this can be sent to ASI for identification)
• Get the victim to a hospital as soon as possible.
• Immobilize the affected limb to slow the spread of venom.
• If the victim stops breathing, apply artificial respiration or use a bag valve mask reserve.
• Call the Poison Information Centre helpline 0861 555 777

DO NOT:

• Apply a tourniquet
• Cut or suck the wound
• Use ice or very hot water
• Give the victim anything to eat or drink (especially not alcohol)
• Apply electric shock
• Inject antivenom randomly (antivenom, if required must be administered by a trained medical professional)
• “Antihistamines are very commonly given, these have no beneficial effect and should be discouraged” Bergman, 1997.
• Opioid painkillers such as pethidine and morphine are ineffective and create a low breathing rate in the patient which may cause respiratory distress.

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How to avoid scorpion stings:

Scorpions are nocturnal and caution should be taken when out and about at night.

• Wear closed shoes when outside at night.
• Use a scorpion torch when out a night (scorpions fluoresce under ultraviolet light and are easy to see at night)
• Be cautious when collecting firewood as many species hide under branches or bark.
• Be careful when packing up tents, as scorpions like to hide underneath them.
• Shake out shoes before putting them on.

We have a number of links on our website that can assist with the quick identification of common scorpions for each province:

Eastern Cape
Free State
Gauteng
KwaZulu - Natal
Limpopo
Mpumalanga
North West Province
Northern Cape
Western Cape

You can also make use of the scorpion information on our free app, ASI Snakes. As well as our free downloadable poster on the Common Scorpions of Southern Africa. 

References
 

1. Bergman, N.J. 1997. Scorpion sting in Zimbabwe. South African Medical Journal, 87(2), pp.163-167.
2. Müller, G.J. 1993. Scorpionism in South Africa: a report of 42 serious scorpion envenomations. South African Medical Journal, 83(6), pp.405-411.
3. Müller, G.J., Modler, H., Wium, C.A. and Veale, D.J.H., 2012. Scorpion sting in southern Africa: diagnosis and management. Continuing Medical Education, 30(10)..
4. Newlands, G. 1978. Review of southern African scorpions and scorpionism. South African Medical Journal, 54(15), pp.613-615.

For those who missed it, the February edition of our ASI Herpetological Association Herp Bulletin is live on our website.

This edition includes notes on a Puff Adder bite, more on Thanatosis, a trip report of Niassa reserve, the typical Toads of South Africa and a recap on the new species from 2020.

You can view the latest Herp Bulletin on our website here.

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