Accidents with venomous animals are frequent in Brazil, including snakes, scorpions and spiders. In our country there are three genera of spiders that are of medical importance: Phoneutria, Loxosceles and Latrodectus . Crab ( Megalomorphae) , although much feared, do not cause serious problems.
Among the species that cause the most accidents, those of the Phoneutria genus stand out , popularly known as “armadeira spiders” . They receive this name because, when they feel threatened, they raise their front legs and support themselves on their rear legs. These species do not build webs and are hidden during the day under debris, firewood, in plants, such as banana and palm trees, among other places.
The bite of the spider spider causes local pain that radiates through the limb that was hit. There is swelling and redness at the site. In more severe cases, intense vomiting, seizures, heart failure, pulmonary edema, coma and even death can occur. Analgesics and anesthetics are used for the treatment. Serotherapy is only indicated for children under seven and people who have serious accidents.
Spiders of the genus Loxosceles , also known as ” brown spiders” , have nocturnal habits and are hidden in places that have little light, such as under debris, clothing and shoes. Unlike wanders, these spiders build webs.
The bite of this spider only causes symptoms after a few hours of the accident, making people slow to seek medical help. Two different forms of clinical manifestations due to the bite are recognizable: the cutaneous and the visceral cutaneous. In the cutaneous form, signs and symptoms are observed exclusively at the site of the bites, such as pain, tingling, swelling and redness. Over time, the color of the site changes to purple and whitish areas and hemorrhagic areas appear. After approximately two weeks, the formation of an ulcer begins.
In the cutaneous-visceral form, there are fever, chills, weakness, nausea, vomiting, myalgia, anemia, jaundice, bleeding, among other symptoms. In more severe cases, it can cause renal failure and death.
The treatment for accidents with Loxosceles spiders is based on serotherapy and the use of anti-inflammatory and analgesics.
The species of the genus Latrodectus are popularly known as “black widows ” and cause few accidents in Brazil, with the female always being responsible for the bite. They are characterized by having a relatively small body and building webs. Its poison is highly toxic and attacks the nervous system, causing severe muscle pain, as well as nausea, headache and cardiorespiratory problems. In some cases, it can lead to death. In cases of serious accidents, serotherapy is indicated.