Close
New

Medscape is available in 5 Language Editions – Choose your Edition here.

 

Widow Spider Envenomation

  • Author: Sean P Bush, MD, FACEP; Chief Editor: Joe Alcock, MD, MS  more...
 
Updated: Jun 29, 2016
 

Background

Widow spiders belong to the genus Latrodectus and include the black widow spider (Latrodectus mactans mactans) in the United States. The term widow spider is used because not all species in the genus Latrodectus are black. Other widow spiders in North America include the brown widow (Latrodectus geometricus), the red-legged widow (Latrodectus bishopi), Latrodectus variolus, and Latrodectus hesperus. The redback spider (Latrodectus hasselti) is endemic to Australia. Latrodectus mactans tredecimguttatus and Latrodectus pallidus are found in Europe and South America, and the button spider (Latrodectus indistinctus) is found in South Africa.

The adult female black widow spider is approximately 2 cm in length and shiny black with a red-orange hourglass or spot on the ventral abdomen. The male is much smaller, brown, and incapable of envenomating humans. Juvenile females are also brown but have the general body morphology of the adult. Males and juveniles have a pale hourglass shape, similar to adult females. The female sometimes eats the male during or after copulation. Webs are irregular, low-lying, and commonly seen in garages, barns, outhouses, and foliage. Other widow spiders are generally black but may have red spots, such as Latrodectus mactans tredecimguttatus, or a dorsal red stripe, such as the redback spider. Latrodectus geometricus is brown with red and yellow markings.

Latrodectus mactans is shown in the images below.

Black widow spider (Latrodectus mactans) with egg Black widow spider (Latrodectus mactans) with egg sac. Photo by Sean Bush, MD.
Black widow spider (Latrodectus mactans) and offsp Black widow spider (Latrodectus mactans) and offspring. Photo by Sean Bush, MD.
Black widow spider. Reprinted with permission from Black widow spider. Reprinted with permission from Cutis 1995; 56: 257.

Envenomation is an uncommon occurrence with an extremely variable presentation. Treatment of envenomation often is based on speculation and anecdote, and much of the literature is contradictory. This article attempts to keep recommendations in agreement with the most current standards of care. This article serves as a guideline, and the clinician should use judgment for individual patient encounters.

See Arthropod Envenomation: From Benign Bites to Serious Stings and Venomous Spider Bites: Keys to Diagnosis and Treatment, Critical Images slideshows, for help identifying and treating various envenomations.

Next

Pathophysiology

Alpha-latrotoxin causes the toxic effects observed in humans by opening cation channels (including calcium channels) presynaptically, causing increased release of multiple neurotransmitters. This results in excess stimulation of motor endplates with resultant clinical manifestations. Clinically, the predominant effects are neurological and autonomic, in contrast to the dermonecrotic local effects associated with spiders causing necrotic arachnidism (eg, brown spiders [Loxosceles species]).

Previous
Next

Epidemiology

According to the 2014 Annual Report of the American Association of Poison Control Centers’ National Poison Data System (NPDS), approximately 1700 widow spider bites were reported for 2014,[1] although this figure is probably conservative because of underreporting. No deaths caused by widow spider envenomation have been reported to the AAPCC since its first annual report in 1983.[1] Deaths after black widow spider bites were reported in 2001,[2] 2003,[3] and 2006 in Spain, Greece, and Albania (2 deaths), respectively.[4]

Previous
Next

Prognosis

The vast majority of patients with widow spider envenomations recover fully.

Previous
Next

Patient Education

For patient education resources, see the Bites and Stings Center, as well as Black Widow Spider Bite and Brown Recluse Spider Bite.

Previous
 
 
Contributor Information and Disclosures
Author

Sean P Bush, MD, FACEP Professor of Emergency Medicine, The Brody School of Medicine at East Carolina University

Sean P Bush, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians, International Society on Toxicology, Society for Academic Emergency Medicine, Wilderness Medical Society

Disclosure: Received honoraria from BTG Inc. for speaking and teaching.

Coauthor(s)

Jennifer P Cohen, MD Emergency Physician, Mt Graham Regional Medical Center; Medical Toxicologist, Arizona Poison and Drug Information Center

Disclosure: Nothing to disclose.

Specialty Editor Board

John T VanDeVoort, PharmD Regional Director of Pharmacy, Sacred Heart and St Joseph's Hospitals

John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists

Disclosure: Nothing to disclose.

James Steven Walker, DO, MS Clinical Professor of Surgery, Department of Surgery, University of Oklahoma College of Medicine

James Steven Walker, DO, MS is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Osteopathic Emergency Physicians, American Osteopathic Association

Disclosure: Nothing to disclose.

Chief Editor

Joe Alcock, MD, MS Associate Professor, Department of Emergency Medicine, University of New Mexico Health Sciences Center

Joe Alcock, MD, MS is a member of the following medical societies: American Academy of Emergency Medicine

Disclosure: Nothing to disclose.

Additional Contributors

Robert L Norris, MD Professor, Department of Emergency Medicine, Stanford University Medical Center

Robert L Norris, MD is a member of the following medical societies: American College of Emergency Physicians, Society for Academic Emergency Medicine, International Society of Toxinology, American Medical Association, California Medical Association, Wilderness Medical Society

Disclosure: Nothing to disclose.

References
  1. Mowry JB, Spyker DA, Brooks DE, McMillan N, Schauben JL. 2014 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 32nd Annual Report. Clin Toxicol (Phila). 2015. 53 (10):962-1147. [Medline]. [Full Text].

  2. Gonzalez Valverde FM, Gomez Ramos MJ, Menarguez Pina F, Vazquez Rojas JL. [Fatal latrodectism in an elderly man]. Med Clin (Barc). 2001 Sep 22. 117(8):319. [Medline].

  3. Pneumatikos IA, Galiatsou E, Goe D, Kitsakos A, Nakos G, Vougiouklakis TG. Acute fatal toxic myocarditis after black widow spider envenomation. Ann Emerg Med. 2003 Jan. 41(1):158. [Medline].

  4. Hoxha R. Two Albanians die from black widow spider bites. BMJ. 2006 Aug 5. 333(7562):278. [Medline]. [Full Text].

  5. Bush SP, Thomas TL, Chin ES. Envenomations in children. Pediatr Emerg Med Rep. 1997. 2:1-12.

  6. Woestman R, Perkin R, Van Stralen D. The black widow: is she deadly to children?. Pediatr Emerg Care. 1996 Oct. 12(5):360-4. [Medline].

  7. Bush SP. Black widow spider envenomation mimicking cholecystitis. Am J Emerg Med. 1999 May. 17(3):315. [Medline].

  8. Allen RC, Norris RL. Delayed use of widow spider antivenin. Ann Emerg Med. 1995 Sep. 26(3):393-4. [Medline].

  9. Cohen J, Bush S. Case report: compartment syndrome after a suspected black widow spider bite. Ann Emerg Med. 2005 Apr. 45(4):414-6. [Medline].

  10. Clark RF. The safety and efficacy of antivenin Latrodectus mactans. J Toxicol Clin Toxicol. 2001. 39 (2):125-7. [Medline].

  11. Murphy CM, Hong JJ, Beuhler MC. Anaphylaxis with Latrodectus antivenin resulting in cardiac arrest. J Med Toxicol. 2011 Dec. 7 (4):317-21. [Medline]. [Full Text].

  12. Isbister GK, Page CB, Buckley NA, Fatovich DM, Pascu O, MacDonald SP, et al. Randomized controlled trial of intravenous antivenom versus placebo for latrodectism: the second Redback Antivenom Evaluation (RAVE-II) study. Ann Emerg Med. 2014 Dec. 64 (6):620-8.e2. [Medline].

  13. Dart RC, Bogdan G, Heard K, Bucher Bartelson B, Garcia-Ubbelohde W, Bush S, et al. A randomized, double-blind, placebo-controlled trial of a highly purified equine F(ab)2 antibody black widow spider antivenom. Ann Emerg Med. 2013 Apr. 61 (4):458-67. [Medline].

  14. Dart, RC, Heard, K, Bush, SP et al. A Phase III Clinical Trial of Analatro [Antivenin Latrodectus (Black Widow) Equine Immune F 9ab')2] in Patients with Systemic Latrodectism. Accepted to Clin Tox (will be presented as abstract at 2016 NACCT).

  15. Boyer LV, Binford GJ, Degan JA. Spider Bites. Auerbach PS, ed. Wilderness Medicine. 6th ed. St. Louis, Mo: Mosby; 2011. 975-95.

  16. Bush SP, Naftel J. Injection of a whole black widow spider. Ann Emerg Med. 1996 Apr. 27(4):532-3. [Medline].

 
Previous
Next
 
Black widow spider (Latrodectus mactans) with egg sac. Photo by Sean Bush, MD.
Black widow spider (Latrodectus mactans) and offspring. Photo by Sean Bush, MD.
Black widow spider. Reprinted with permission from Cutis 1995; 56: 257.
 
 
 
All material on this website is protected by copyright, Copyright © 1994-2016 by WebMD LLC. This website also contains material copyrighted by 3rd parties.