SAMT VOL 73 20 FEB 1988 235

Review of southern African spiders ofmedical importance, with notes on thesigns and symptoms of envenomationG. NEWLANDS, P. ATKINSON

Summary

Medically important spiders in southern Africa arediscussed in terms of their morphological featuresand distribution, the signs and symptoms of enveno­mation and the possible treatment thereof. A simplepictorial key is provided to enable the non-specialistto identify the neurotoxic and cytotoxic species. Thefollowing spiders are now known to be medicallyimportant in southern Africa: Latrodectus indistinctus(neurotoxic), Chiracanthium lawrencei (cytotoxic),Loxosceles sp. (cytotoxic) and Sicarius sp. (cytotoxic- haemotoxic).

structure of egg cases can also be important. With all thesefeatures noted, it should be a simple matter to recognise thespider in the pictorial key (Fig. 1).

Since publication of the' last review,1 52 cases of proven orsuspected spider bite in South Africa have been brought to myattention. Of these, 11 were diagnosed as having been causedby bacterial infection (Staphylococcus sp.) probably unrelatedto spider bite, and 1 as having been due to chromium sensitivitycaused by a watch strap. The remaining 40 were thought to bespider bites (Table I). Oearly, Chiracanthium sp. is responsiblefor most bites in the Pretoria-Witwatersrand area, followed byLoxosceles sp. and Lacrodectus sp. It appears to be a rule ofthumb that spiders that live in webs are generally neurotoxicwhereas the free-ranging species are cytotoxic.

S Afr Med J 1988; 73: 235-239.

'Genus and species could nol be established.

Pretoria-WitwatersrandN. Transvaal, N. W. CapeJohannesburgPretoriaWindhoekJohannesburg

LocalityPretoria-WitwatersrandPretoria-Witwatersrand

422111

1811

Species

Chiracanthium sp.Loxosceles sp.LatrodectusindistinctusSicarius sp.Harpactira sp.Palystes nataliusGnaphosid*Salticid*

TABLE I. ANALYSIS OF 40 CASES OF SPIDER BITE OVER A. 10-YEAR PERIOD

No. ofbites

Notes on the species and their toxic effects

Neurotoxic speciesLatrodectus indistinctus ope (family Theridiidae)(Fig. 2)

Synonym. Formerly known as L. maccans.Vernacular names. Black widow, button spider, knoppie­

spinnekop.Distribution. Widespread throughout southern Africa.Description. This is an intensely black spider of velvet

texture. Young specimens have a prominent red stripe orstripes dorsally on the abdomen. With each moult, the sizeand intensity of these stripes diminishes until all that remainsin old specimens is a dull red dot above the spinnerets.Occasionally, specimens have faint yellow transverse markingsanterodorsally on the abdomen but there are never any ventralmarkings. The first pair of legs is the longest and the thirdpair the shortest. Body length is about 13 mm and leg span upto 40 mm. Egg cases are of smooth silken texture. The male ofthe species is very small, inconspicuous and of no medicalimportance whatever.Accepted 11 Nov 1986.

Since medically important spiders were last reviewed,1a greatdeal of research ·has been done. Spiders of the generaChiracanthium (Clubionidae) and Sicarius (Sicariidae) havebeen added to the list. 2

,3 Loxosceles (Scytodidae) has beenincriminated beyond doubt,4-6 especially in the' Johannesburgarea, and Palysces nacalius (Sparassidae) has been provedharmless.7 In addition, the taxonomic status of the local blackwidow spider has changed.8These changes tend to confuse thenon-specialist and there is thus a need for a review and key tothe species at this stage. A simple key to the species has beendevised for use by non-specialists.

The medically important spiders of southern Africa can bedivided into two categories according to the action of theirvenoms, viz. neurotoxic and cytotoxic species. A single species,Lacrodectus indiscinceus, represents the neurotoxic group insouthern Africa. Formerly, this species was known as L.maccans which was thought to have a world-wide distribution. 1,8Three genera represent the cytotoxic category in southernAfrica, viz. Chiracanthium, Loxosceles and Sicarius. Species ofthe first two genera are known to be medically important inother parts of the world but Sicarius is a unique new find.

Although more than 30 000 spider species are known toscience, the medically important species are surprisingly easyto identify if a few simple observations are possible. Theseobservations are best made' with a stereomicroscope or powerfulhand lens. The following should be carefully noted: bodylength, leg span, general colour, body markings and the preciseeye pattern. Note if the species was found in a web. The

Department of Entomology, University of PretoriaG. NEWLANDS, PH.D.Department of Haematology, South African Institute forMedical Research, JohannesburgP. ATKINSON, M.B. RCH., PH.D. (MED.)

236 SAMJ VOL 73 20 FEB 1988

ISPIDER WITH 6 EYES 11 SPIDER WITH 8 EYES I

Body length gmm, leg span 50mm

Small and delicate with long thin legs

Body length 14mm, leg span 35mm

Medium sized spider

Lives in cobwebs amongst grass and rocks

Black with red dorsal stripe or stripes orsimply red dot above spinnerets. No ventralred marking whatever. Velvet texture.

Egg case smooth and lOmm across

Free ranging hunter. Found in foliage, fastmoving species.

Medium sized spider

Straw . colou red body with glossy blackchelicerae

NEUROTOXIC

CYTOTOXIC

Latrodec tus sp

•••••••••I••••••••••

it

•••••••••••••••

~;

~. .t• •• •••••••

dorso-ventral'yspider,

Loxosceles sp

Brownish or dark brown with black markings

Violin-shaped marking on carapace

Free ranging h~nter, found beneath rocksin caves or dark corners of houses

Body covered with sand particles fromhabitat lodged amongst body setae

Lives buried in sand beneath stones, incaves, animal burrows etc.

Large· robustcompressed

Freshly moulted colour yellowish or reddis.hbrown

CYTOTOXIC

CYTOTOXIC

Eyes very smallBody length 13mm, leg span 35mm

Body length 15mm, leg span 50mm

Sicarius Sp Chiracanthium ,Sp

Fig. 1. A pictorial key for the identification of the medically important spiders in southern Africa.

•

Fig. 2. Dorsal view of the black widow spider, Latrodectusindistinctus.

A very closely related species, L. geomeln'cus Koch, is notdangerous although its bite is painful. This species has aprominent orange hour-glass shaped marking ventrally on theabdomen. Its body varies considerably in colour from grey tobrown to black and some specimens have very intricate colourpatterns. Egg cases have numerous pointed projections overtheir entire surface which is characteristic of the species.

Clinical features of envenomation. Systemic symptomsoccur within 20 minutes of the normally painful bite. Thesemay include excruciating cramp-like pains in the chest andabdomen, and in the articulation points of limbs. Other possiblesymptoms include abdominal rigidity, difficulty in breathing,tightness across the chest, blurred vision, perspiration, pyrexiaand restlessness. 1

,9,1O While the symptoms are dramatic, thereis little threat to life in healthy adults.. People with cardio­respiratory problems and very young children are at smue risk.

Treatment. Calcium gluconate 10% (10 ml) given intra­venously provides relief for between IS and 30 minutes. Aspecific antivenom is available from the South Mrican Institutefor Medical Research, PO Box 1038, Johannesburg 2000; tel.(011) 640-7130 (a/h 640-5959).

SAMT VOL 73 20 FEB 1988 237

10 mm

Fig. 3. Dorsal view of the sac spider, Chiracanthium lawrencei.

Cytotoxic speciesChiracanthium lawrencei Strand (family Clubio­nidae) (Fig. 3)

Vernacular name. Sac spider.Distribution. Very common and widespread in South

Mrica.Description. A straw-eoloured spider with large, shiny

black mouthparts. It has 8 eyes arranged in two parallel rowsof 4. The eyes in the upper row ;rre smaller than those in thelower row. These spiders are fast-moving and aggressive. Thebody length is up to 14 mm and the leg span about 40 mm forfemales and 50 mm for males. The male's body is smaller andmore slender than the female's.

Habitat. Sac spiders live in the concavity of leaves overwhich they spin a few strands of silk to form a sack, hence thecommon name. They are equally at home in the corners ofdoors and walls and among the folds of curtains and garments.At night these spiders leave their retreats in search of food andmates.

Clinical features of envenomation. Most victims arebitten while asleep in bed or when dressing in garmentsharbouring the spiders. The bite'is not particularly painful andinitially the only signs of envenomation are two small greenishor yellowish necrotic spots 6 - 8 mm apart representing thefang entry points. Chinuanrhium sp. have the widest gapbetween the fangs of all the local medically important species,and this is thus of great diagnostic value. The venom is agreenish-yellow colour. Gradually, the area surrounding thesite of the bite becomes erythematous and oedematous andvery painful. Mter 4 - 5 days the lesion ulcerates leaving anecrotic area about 10 mm across. The lesion should healwithin 2 weeks. A secondary, painless lesion often develops

238 SAMJ VOL 73 20 FEB 1988

Fig. 4. Dorsal view of the violin spider, Loxosceles parrami.

soon after the primary lesion has healed and is characterisedby very slight oedema and a blueish skin discoloration re­sembling a bruise. However, histological examination of theselesions in rabbits failed to reveal extravasation. Roughly aquarter of victims present with signs and symptoms of tick­bite fever 3 days after envenomation. This can lead to mis­diagnosis. However, the lack of a black eschar at the site of thebite and the short incubation period should guide the clinicianin this regard. The symptoms are a direct toxic effect of thevenom. Spiders are extremely unlikely vector species.

Treatment. The lesion is self-limiting and normally healswithout problems provided secondary infections are prevented.Treatment should thus be directed at preventing secondaryinfection from about the 2nd day after envenomation. Noantivenom is available.

Loxosceles sp. (family Loxoscelidae) (Fig. 4)Common species. L. parrami Newlands (Witwatersrand),

L. spiniceps Lawrence (Natal, Transvaal, Botswana, Zimbabwe),L. pil/osa Purcell (South West MricalNamibia, north-westernCape), L. bergeri Strand (South West MricalNamibia).

Vernacular names. Violin spider, fiddle-back spider, brownspider.

Distribution. Widespread in southern Mrica south of 17°S.Diagnosis. Two distinct groups of species occur in southern

Mrica, viz. 4 spelaean and 5 savanna species. Loxoscelinespiders can be recognised by the 6 eyes arranged in a U­shaped recurved row, the violin-shaped marking on the carapace(head region), the small body (9 mm in length) and the wideleg span (50 mm). The legs are very delicate and easilydamaged. The savanna species are light brown to goldenbrown with black markings whereas the spelaean species aredark brown with black markings. The spelaean species havesmaller more widely spaced eyes than the savanna species.

Habitat. Savanna species live beneath rocks and logs or insmall abandoned burrows. The natural habitat of spelaeanspecies is beneath rocks and in the 'cracks and crevices of cavewalls. L. parrami, which was artificially introduced into the

Witwatersrand,4,6 survives very well in the urban environment.It is found in the dark nooks and crannies of many homes orin the cracks and crevices of the foundations. It is often foundbehind picture frames, in dark corners of cupboards anddrawers, or in boxes used for storage. Other day-time hidingplaces are among clothing and in shoes. Roughly 70% ofloxosceline envenomations take place while the victim is asleep.In most of the remaining cases (3 out of the 11 patientsstudied) loxoscelism occurred when the victims put on shoesharbouring spiders.

Clinical features of envenomation. The bite of localloxoscelines is very superficial and rarely penetrates the epi­dermis, because the fangs are so small. Accordingly, the bite isseldom if ever felt and the venom takes some time to diffuseinto the underlying tissues with vascular supply. Roughly 2hours after the bite, an oedematous, erythematous lesion witha purple centre develops about the site. No fang marks arevisible. Gradually over a period of 1 - 2 days, the lesiondevelops, into a blackish area of intense oedema 20 - 60 mmacross, surrounded by an inflamed zone up to 120 mm across.On the 4th day, the oedematous area subsides and the necrosisspreads slowly. Mter about 10 days, the necrotic tissues sloughleaving an ulcerating wound up to 100 mm across, and involvingthe entire depth of the dermis. The lesion takes a long time toheal.

While the local signs and symptoms are essentially the sameas those reported for loxoscelism in north and southAmerica,! I, 12 there are important differences. None of the localvictims of loxoscelism has had systemic complications. Thereason is not that the venom of southern Mrican species is lesstoxic but rather that the dose administered during biting isconsiderably lower. Local species are roughly half the size ofthe American species, L. guacho and L. reclusa. The venomglands are cylindrical and if the size is doubled the volumeincreases eightfold, so while adults are unlikely to developsystemic symptoms, the possibility exists that they coulddevelop in very young children. Rabbits challenged with localloxosceline venoms developed mild disseminated intravascularcoagulation (DIC). Defibrination syndromes have been reportedin America following bites by L. reclusa. 13

,14 Another importanttoxic difference is that both experimentally envenomated rabbitsand local victims developed no signs whatever of haemolysis.Haemolysis has frequently been described in cases of Americanloxoscelism.II,15,16 In vicro tests done in our laboratory inwhich human erythrocytes were incubated with Loxosceles andSican'us venoms failed to demonstrate any haemolytic effect.

Treatment. A great deal of controversy exists regarding theuse of steroid therapy for loxoscelism, and there is no convinc­ing evidence that even early treatment reduces the inflammationand eventual necrosis. Rabbits challenged with Loxoscelesvenoms in our laboratory were routinely treated with Kemi­spray (panvet; Kempton Park), a veterinary product consistingof 10% chloramphenicol and gentian violet designed for thetreatment of foot rot in cattle and sheep. The lesions dried outand healed surprisingly quickly and no case of secondaryinfection developed. Four human victims have been treatedwith this product and they appear to have healed more rapidlythan would otherwise have been expected. In any event, it isexpedient to administer antibiotics to human sufferers sincesecondary infections are a problem. It should also be borne inmind that fungal infections are a real possibility and it ispossible that the gentian violet in the Kemispray will preventsuch infection. No antivenom is available.

Sicarius sp. (family Sicariidae) (Fig. 5)Common species. S. hahni Karsch (north-western Cape,

South West MricaINamibia), S. cestaceus Purcell (western andsouthern Cape), S. oweni Newlands (Transvaal).

•

Fig. 5. Dorsal view of the Transvaal 6-eyed crab spider, Sicariussp. This species is to be named in honour of E. Owen.

Vernacular name. Six-eyed crab spider.Distribution. Widespread in the arid and seini-arid regions

of southern Mrica.Description. A large spider with a body length of 15 mm

and a leg span of 50 mm. The body is dorsoventrally com­pressed and very firm, and the cuticle is leathery and denselycovered with tiny hair-like spines. The spider has 6 tiny eyesin 3 diads which are widely separated and arranged in arecurved U-shaped row. These spiders do not make webs at alland spend virtually their entire lives motionless while buriedin sand beneath rocks or in caves. Sand particles from theenvironment become. trapped between spines covering thebody surface. Thus the spider takes on the colour and textureof the environment and is well camouflaged. The spider'sintegument is yellowish- or reddish-brown. These spiders livefor at least 12 years.

Clinical features of envenomation. Two cases of sus­pected sicarism have been reported to us but as we did not seethe patients personally, it will be more expedient to describethe signs and symptoms seen in numerous experiments withrabbits. The lesions began with a purple discoloration at thecentre of a well-defmed weal which persisted for about anhour. Mter 6 hours, a 50 - 100 mm lesion had developed. Thislesion had a black central zone 20 - 30 mm across which wasintensely necrotic and disintegrated if touched. This wassurrounded by a haemorrhagic and ecchymotic zone whichshowed little sign of oedema or erythema and thus contrastedmarkedly with lesions caused by loxoscelism. The rabbits

SAMT VOL 73 20 FEB 1988 239

collapsed and died within 5 - 12 hours. Other importantfindings were petechial haemorrhages in the liver, lungs andheart. Haematomas were seen in the skin far removed from thebite site. Eosinophilic aggregates were detected histologicallyin the liver and lungs where foci of necrosis were also found.Aggregates of mononuclear cells were seen in the endocardiumand there were also foci of necrosis of the cardiac muscle. Therabbits developed biocheinical evidence of DIe. The mainfeatures of Sicarius envenomation can be summarised as massivetissue destruction and widespread haemorrhage in keepingwith DIe. .

Treatment. No antivenom is available and treatment shouldbe directed at combating seconaary infections and DIC if itdevelops.

Note. At least two species, S. hahni and S. albospinosus,must be regarded as potentially lethal. Based on rabbit experi­ments, they must be regarded as beipg among the world'smost dangerously venomous spiders. Fortunately they are notat all aggressive and most people are extremely unlikely ever tocome into contact with them. The only people at risk areamateur spider collectors, geologists and people who sleep onthe ground in sandy areas in or near caves and rock overhangs.National servicemen inight fall into this latter category.

I am most grateful to the South African Medical ResearchCouncil for funding much of the research which made this reviewpossible, to Miss Beth Grobbelaar for the illustrations, and toMessrs C. R. and E. Owen for collecting spiders.

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I!. Schenone H, Suarez G. Venoms of Seytodidae: genus Lorosceles. In: BettiniS, Bertini S, eds. Handbook of Erperimenral Pharmacology. New York:Springer-Verlag, 1978: 247-275.

12. Wasserman GS, Anderson Pc. Loxoscelism and necrotic arachnidism. ]Toncol Clin ToncoI1984; 21: 451-472.

13. Vorse H, Woodruff K, Humphrey GB. Disseminated intravascular coagula­parhy following fatal brown spider bite (necrotic arachnidism). ] Pediarr1972; 80: 1035-1038.

14. Berger RS, Adelsrein EH, Anderson Pc. Intravascular coagulation: thecause of necrotic arachnidism.] Invesr Dermarol 1973; 61: 142-150.

15. Chu J, Rush cr, O'Connor DM. Hemolytic anemia following brown spider(Lorosceles reclusa) bite.] Tomol Clin Tomo11978; U: 531-534.

16. Eichner ER. Spider bite hemolytic anemia: positive Coombs' test, erythro­phagocytosis, and leukoeryrhroblastic smear. Am] Clin Parhol 1984; 81:683-687.