Spiders are arthropod animals that may not be mistaken for insects. More than 40.000 different species of them exist all over the world.
They don't bite unless they are menaced and, a lot of the times, the bites go totally unnoticed.
When symptoms are caused, those are usually in the form of reddening, pain, and swelling of the bitten area. The symptoms are very common and are pretty similar to those of other types of bites so it is difficult to assess if it really was a spider bite if the animal was not observed at the moment of the bite. Some of the species inoculate a venom that is strong enough to cause severe symptoms; usually this happens in black widow bite cases, that can cause severe pain in both thorax and abdomen, nausea, vomits, tremor, sweats and a fall in the arterial tension. Brown recluse spider bites can also be severe, manifesting with acute pain, fever, hypotension and lesions in the skin of purple colouration that can turn into ulcers.
Usually it is diagnosed when observing the spider at the moment of the bite. Taking a picture or describing the spider can guide professionals or rule out the bite for its venomous factors.
The vast majority of bites don't need treatment and heal by themselves. It is recommended washing with water and soap the area of the bite to avoid its infection; in some occasions an antibiotic unguent can be used as a treatment. If there is pain and/or swelling analgesics and/or anti-inflammatory drugs can be administered; If those cannot be administered, a cold pack can be applied for 15 minutes every hour to relief the symptoms. If there are signs of infection or if it turns into a cutaneous ulcer, antibiotic treatment must be started.
If it is a black widow bite, there is an antidote that can be administered intravenously. It must be administered under medical supervision because it can cause severe allergic reactions.
Black widows tend to live in garden areas, barns, wood piles, behind flowerpots, etc. It is also common to find them in unused cabinets.
The brown recluse spider lives in atics and basements where shelters and less used wardrobes can be found.
- Vetter RS, Isbister GK. Medical aspects of spider bites. Annu Rev Entomol 2008; 53:409.
- Liu K, Wang M, Herzig V, et al. Venom from the spider Araneus ventricosus is lethal to insects but inactive in vertebrates. Toxicon 2016; 115:63.
- Isbister GK, Fan HW. Spider bite. Lancet 2011; 378:2039.
- Russell FE, Gertsch WJ. For those who treat spider or suspected spider bites. Toxicon 1983; 21:337.
- Wong RC, Hughes SE, Voorhees JJ. Spider bites. Arch Dermatol 1987; 123:98.
