Part 2 – SPIDERS WITH MEDICALLY SIGNIFICANT VENOM

Our button or widow spiders have neurotoxic venom (venom that affects the central nervous system).

BLACK BUTTON OR WIDOW SPIDERS

Family Theridiidae, species Latrodectus cinctus, Latrodectus indistinctus, Latrodectus karrooensis & Latrodectus renivulvatus

Black button spiders are regarded as the most dangerously venomous spiders found in southern Africa.

Those found in southern Africa do not have the red hourglass marking under the abdomen but can have a variety of pretty red and gold markings on the upper side, fading in older individuals to a dull red dot above the spinnerets or disappearing altogether.  Egg sacs are smooth, usually spherical, sometimes tear-drop shaped and about the size of a large green pea. Mature female’s abdomens are also about pea sized.  They make three dimensional webs of very tough silk with a retreat to one side in a variety of sheltered spots, usually outdoors.  Males are very small and harmless to humans.

The potent venom affects the nervous system, causing severe systemic symptoms and local pain, this is called Latrodectism.  In South Africa there have been no recorded human deaths for more than 7 decades. An antivenin is available in South Africa.  Although they are reluctant to bite, preferring to “play dead” if disturbed, proven button spider bites must be taken seriously and medical attention sought.

Brown Button Spiders (Widow Spiders)

Latrodectus geometricus and Latrodectus rhodesiensis Family Theridiidae

Brown Button spiders, despite their name, can be creamy white to very dark blackish brown.  They do have a red or orange double-isosceles-triangle marking under the abdomen.  Egg sacs of the Rhodesian Button spider are spherical, large and fluffy.  The much more common Brown Button Spider’s egg sacs are spherical and covered in little silken spikes.   They make three dimensional webs of very tough silk with a retreat to one side in a variety of sheltered spots.  Brown Button Spiders are common, widespread and often found in and around human habitation.   Males are very small and harmless to humans.

Venomous

Brown button spider venom is similar to that of black button spiders but less potent. They are reluctant to bite, preferring to “play dead” if disturbed.    Medical attention should be sought if symptoms occur although there are only a few known cases of Latrodectism from the bite of a brown Button Spider that have needed treatment.  The antivenin for all cases of Latrodectism is available in South Africa.  No human deaths have been recorded.

TREATMENT OF BUTTON/WIDOW SPIDER BITES (Neurotoxic venom)

Hospitalisation and monitoring of vital signs for at least 24 hours

There are no investigations of value in establishing the diagnosis.

If symptoms develop (they don’t always) they should at first be treated symptomatically and in severe cases Latrodectus spider antivenin obtainable from South African Vaccine Producers (Pty.) Ltd. Tel (011) 386-6000 or 386-6063 must be administered and this should only be done by a trained medical professional.  It should be readily available and kept in all hospitals.   Calcium gluconate solution can be given intravenously to give some relief from cramps. Patient should be hydrated intravenously.

The bite site must be kept clean, uncovered and not interfered with.

Avoid Opioids and give a Tetanus toxoid.

Next week  Part 3- SPIDERS WITH MEDICALLY SIGNIFICANT VENOM – Violin and Six-Eyed spiders

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