spiders; however, as these cases are often mild and the evidence of its effectiveness is limited, this treatment is not recommended. Similarly, the antivenom has been reported as effective with bites of L. katipo, and L. tredecimguttatus. Animal studies also support its use against envenomation from other widow spiders, having successfully been tested against venom from L. mactans, L. hesperus, and L. tredecimguttatus (synonym L. lugubris). Signs and symptoms Envenomation from a redback spider bite produces a syndrome known as latrodectism. A small but significant percentage of people bitten develop significant pain or systemic symptoms. The diagnosis is made from the clinical condition, often based on the victim being aware of a bite and ideally with identification of the spider. Laboratory tests are rarely needed and there is no specific test for the venom or latrodectism. The redback's small size means that swelling or puncture marks at the bite site are uncommon. The bite may be painful from the start, but more often only feels like a pinprick or mild burning sensation. Within an hour, a more severe local pain may develop with local sweating and sometimes piloerection (goosebumps)—these three symptoms together are a classic presentation of redback spider envenomation. Pain, swelling and redness can spread proximally up a limb or away from the bite site and regional lymph nodes may become painful. Some subjects with delayed symptoms may present with a characteristic sweating and pain in the lower limbs, generally below the knees, or a burning sensation in the soles of the feet. This may eventuate even if the person was bitten somewhere else on their body. Around one in three subjects develops systemic symptoms; after a number of hours, or rarely, delayed for more than 24 hours. Symptoms typically include nausea, vomiting, abdominal or chest pain, agitation, headache, generalised sweating and hypertension. Other non-specific systemic effects such as malaise and lethargy are also common. Rarely, other effects are reported such as neurological manifestations, fever and priapism (uncontrolled erection of the penis). Severe pain usually persists for over 24 hours after being bitten. Symptoms of envenomation may linger for weeks or even months. Rare complications include localised skin infection, seizure, coma, pulmonary oedema, or respiratory failure. Children, the elderly, or those with serious medical conditions are at much higher risk of severe effects resulting from a bite. Infants have died within hours of a bite, but adult fatalities have