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Latrodectus hasseltii
General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid , Antivenoms
Latrodectus hasseltii ( Redback Spider )  [ Original photo copyright © Dr Julian White ]
Suborder: Araneomorphae
Family: Theridiidae
Genus: Latrodectus
Species: hasseltii
Common Names
Redback Spider, Jockey Spider, Red back Spider , Red-back Spider
Local Names
Murra-ngura , Kapara , Kana-jeri
Australia, Belgium, Japan, New Zealand
Taxonomy and Biology
No information available for Taxonomy and Biology
General: Venom Neurotoxins
Excitatory neurotoxins (alpha-latrotoxins)
General: Venom Myotoxins
Not present
General: Venom Procoagulants
Not present
General: Venom Anticoagulants
Not present
General: Venom Haemorrhagins
Not present
General: Venom Nephrotoxins
Not present
General: Venom Cardiotoxins
Not present
General: Venom Necrotoxins
Not present
General: Venom Other
Not present or not significant
Clinical Effects
General: Dangerousness
Severe envenoming possible, potentially lethal
General: Rate of Envenoming: 10-20%
General: Untreated Lethality Rate: Unlikely to prove lethal
General: Local Effects
Initially minor "sting", then progressively severe local pain ± sweating & erythema/blanching.
General: Local Necrosis
Does not occur, based on current clinical evidence
General: General Systemic Effects
General: Myotoxicity
Very rarely cause mild myolysis (CK up to 1500IU/l).
General: Coagulopathy & Haemorrhages
Does not occur, based on current clinical evidence
General: Renal Damage
Does not occur, based on current clinical evidence
General: Cardiotoxicity
Does not occur, based on current clinical evidence
General: Other
Occasionally cause headache, arthralgias, tremors, psychosis, severe trismus, dysuria, dyspnoea.
First Aid
Description: First aid for Widow Spider Bites (includes Australian red back spider)
1. After ensuring the patient and onlookers are no longer at risk of further bites by the spider, the bitten person should be reassured and persuaded to lie down and remain still. Some will be terrified, fearing sudden death and, in this mood, they may behave irrationally or even hysterically. The basis for reassurance is the fact that many bites do not result in envenoming, death is a very rare outcome, and the effectiveness of modern medical treatment.
2. The bite wound should not be tampered with in any way.
3. Some victims find the application of a local cold pack may relieve local pain.
4. Do not apply a local bandage, tourniquet, or cut or suck or incise the wound or apply electric shock. Application of local heat has not proved beneficial.
5. If there is any impairment of vital functions, such as problems with respiration, airway, circulation, heart function, these must be supported as a priority. In particular, both airway and respiration may be impaired, requiring urgent and prolonged treatment, which may include the mouth to mask (mouth to mouth) technique of expired air transfer. Seek urgent medical attention.
6. If the offending spider has been killed or caught it should be brought with the patient for identification.
7. Avoid peroral intake, other than clear fluids, in the first 6 hours, absolutely no alcohol. No sedatives outside hospital. If there will be considerable delay before reaching medical aid, measured in several hours to days, then give clear fluids by mouth to prevent dehydration.
8. Most traditional, and many of the more recently fashionable, first aid measures are useless and potentially dangerous. These include local cauterization, incision, excision, amputation, suction by mouth, vacuum pump or syringe, combined incision and suction ("venom-ex" apparatus), injection or instillation of compounds such as potassium permanganate, phenol (carbolic soap) and trypsin, application of electric shocks or ice (cryotherapy), use of traditional herbal, folk and other remedies including the ingestion of emetic plant products and parts of the snake, multiple incisions, tattooing and so on.
Treatment Summary
Widow spider bites are mostly minor and even significant envenoming is unlikely to be lethal, so after a 6 hr observation, asymptomatic patients can be discharged. Symptomatic patients should be considered for IM or IV antivenom therapy, as this is the only effective treatment for envenoming.
Key Diagnostic Features
Bite felt as "sting", delayed (10+min) local pain ± sweating, then regional pain, tender draining lymph nodes, nausea, hypertension, malaise.
General Approach to Management
While most cases will be minor, not requiring admission, some cases will be more severe, requiring admission and treatment, so assess carefully before early discharge.
Antivenom Therapy
Antivenom only required for major regional or systemic envenoming.
1. Antivenom Code: IAuCSL05
Antivenom Name: Red-backed spider antivenom
Manufacturer: CSL Limited
Phone: ++61-3-9389-1911
Toll free: 1800 642 865
Address: 45 Poplar Road
Victoria 3052
Country: Australia
Latrodectus hasseltii ( Redback Spider ) [ Original photo copyright © Dr Julian White ]
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