Morning Report: Spider Bites

Dr. Kopping presents today’s Morning Report!

Spiders…who needs that many legs, am I right?

Several medically important specimens throughout the world
- I live in North America, which should I care about most?
  - Black Widow
  - Brown Recluse
  - Hobo spider
Black Widow (Latrodectus mactans)
- Likes temperate/tropical climates
- Found in stone walls, crevices, wood piles, barns, trash heaps
  - Think “places where bugs hang out”
- Classic red “hour glass” shape on ventral suface
  - Ventral markings are species specific and vary between other widow spiders
- Female much more dangerous than males given much larger size and fangs that can penetrate human skin
- 6 active components which ultimately lead to leakage of NT’s such as NE, DA, ACh causing the symptoms described below
- Usually not aggressive, nocturnal
  - Bites occur when disturbed or inadvertent contact in shoes/clothing
- Initial bite not that impressive, range from pin prick to unnoticed
- In systemic poisoning, severe pain starts at the site of envenomation and progresses centrally
- Rapid symptom/pain onset is usually concerning for severe envenomation
  - Grade 1- asymptomatic to local pain, normal vitals
  - Grade 2- migration of pain centrally, diaphoresis at the bite site, normal vitals
  - Grade 3- above with abnormal VS, diaphoresis distant from bite, generalized myalgias to back/chest/abdomen, priapism
    - Classic scenario is rigid abdomen, often confused with acute peritonitis, especially in children unable to relay history
  - Life threatening complications- Severe HTN, respiratory distress, MI, CV collapse, gangrene
  - Muscle cramps usually last several hours, but can recur for several days to weeks after envenomation
- Treatment mainly supportive +/- antivenom for critical patients
  - Pain/muscle spasm control
    - Grade 1 likely only needs cold pack and NSAIDs
    - Opiates and BZDs for Grade 2 or 3
  - There is an antivenom available- controversial use
    - Rapidly effective, but high risk of anaphylaxis and serum sickness
      - Horse IgG
    - Morbidity very high, but mortality is low
    - Recommend in very high risk patients (pregnant women with threatened ab, hypertensive crisis, intractable pain, priapism)

References

Hahn I. Chapter 119. Arthropods. In: Nelson LS, Lewin NA, Howland M, Hoffman RS, Goldfrank LR, Flomenbaum NE. eds. Goldfrank’s Toxicologic Emergencies, 9e . New York, NY: McGraw-Hill; 2011. http://accessemergencymedicine.mhmedical.com.newproxy.downstate.edu/content.aspx?bookid=454&Sectionid=40199539. Accessed April 29, 2015.
“Black Widow vs. Brown Recluse” http://www.medicinenet.com/black_widow_brown_recluse_pictures_slideshow/article.htm
Latrodectus. (2015, April 28). In Wikipedia, The Free Encyclopedia. Retrieved 23:01, April 29, 2015, from http://en.wikipedia.org/w/index.php?title=Latrodectus&oldid=659701443