The redback spider (Latrodectus hasselti) is a species of venomous spider
indigenous to Australia. The spider firstly discovered at Osaka prefecture in
1995, has a widespread distribution now in Japan. Female redback spiders have
a body length of about 10 millimeters and are black with a characteristic red
stripe on the upper abdomen. The redback spider is found in proximity to
human habitation, with webs being built in dry, sheltered sites among artificial
products in factory, park, residential and parking area.
The venom of the redback spider contains a neurotoxin called alpha-latrotoxin.
Envenomation from the spider bite produces a significant pain or systemic
symptoms such as generalized sweating, vomiting, abdominal or chest pain,
agitation, headache and hypertension. The diagnosis is made from the clinical
condition with identification of the spider. Various medical conditions including
insect bites, acute myocardial infarction and acute abdomen should be
differentiated from latrodectism.
Treatment is based on the severity of poisoning from the bite. Pain control and
sedation for patients with latrodectism are often required. Antivenom is effective
for severe pain or systemic symptoms but it is difficult to get the antivenom in
Japan in the present situation.