Widow Spider Envenomation

Author: Sean P Bush, MD, FACEP; Chief Editor: Rick Kulkarni, MD more...

Updated: Oct 28, 2010

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Background
Pathophysiology
Epidemiology
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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 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.

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]).

Frequency

United States

Approximately 2500 widow spider bites were reported to the American Association of Poison Control Centers (AAPCC) in 2006, although this figure is probably conservative because of underreporting.^[1]

Mortality/Morbidity

In the United States, an average of 4 deaths per year are reported to occur as a result of spider bites.^[2]However, no deaths caused by widow spider envenomation have been reported to the AAPCC since its first annual report in 1983.^[3]Deaths after black widow spider bites were reported in 2001^[4]and 2003^[5]in Spain and Greece, respectively.^[6]

Proceed to Clinical Presentation

Contributor Information and Disclosures

Author

Sean P Bush, MD, FACEP Professor of Emergency Medicine, Loma Linda University School of Medicine; Consulting Staff, Envenomation Specialist, Department of Emergency Medicine, Loma Linda University Medical Center

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, and Wilderness Medical Society

Disclosure: Protherics Consulting fee Consulting; Nycomed (formerly Fougera) Grant/research funds Speaking and teaching; Rare Disease Therapeutics Grant/research funds Research; Bioclon Grant/research funds Research

Coauthor(s)

Jennifer C Smith, MD Medical Toxicology Fellow, Banner Good Samaritan Poison Center

Jennifer C Smith, MD is a member of the following medical societies: American College of Emergency Physicians

Disclosure: Nothing to disclose.

Specialty Editor Board

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

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

Disclosure: Nothing to disclose.

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, and American Osteopathic Association

Disclosure: Nothing to disclose.

John D Halamka, MD, MS Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center

John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Chief Editor

Rick Kulkarni, MD Attending Physician, Department of Emergency Medicine, Cambridge Health Alliance, Division of Emergency Medicine, Harvard Medical School

Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine

Disclosure: WebMD Salary Employment

References

Bronstein AC, Spyker DA, Cantilena LR Jr, Green J, Rumack BH, Heard SE. 2006 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS). Clin Toxicol (Phila). Dec 2007;45(8):815-917. [Medline].
Langley RL, Morrow WE. Deaths resulting from animal attacks in the United States. Wild Environ Med. 1997;8:8-16.
Watson WA, Litovitz TL, Klein-Schwartz W, Rodgers GC Jr, Youniss J, Reid N, et al. 2003 annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med. Sep 2004;22(5):335-404. [Medline].
Gonzalez Valverde FM, Gomez Ramos MJ, Menarguez Pina F, Vazquez Rojas JL. [Fatal latrodectism in an elderly man]. Med Clin (Barc). Sep 22 2001;117(8):319. [Medline].
Pneumatikos IA, Galiatsou E, Goe D, Kitsakos A, Nakos G, Vougiouklakis TG. Acute fatal toxic myocarditis after black widow spider envenomation. Ann Emerg Med. Jan 2003;41(1):158. [Medline].
Hoxha R. Two Albanians die from black widow spider bites. BMJ. Aug 5 2006;333(7562):278. [Medline].
Boyer Hassen LV, McNally JT, Binford GJ. Spider bites. In: Auerbach PS, ed. Wilderness Medicine. 4^th ed. St. Louis: Mosby-Year Book; 2001:807-838.
Clark RF, Wethern-Kestner S, Vance MV, Gerkin R. Clinical presentation and treatment of black widow spider envenomation: a review of 163 cases. Ann Emerg Med. Jul 1992;21(7):782-7. [Medline].
Bush SP, Thomas TL, Chin ES. Envenomations in children. Pediatr Emerg Med Rep. 1997;2:1-12.
Woestman R, Perkin R, Van Stralen D. The black widow: is she deadly to children?. Pediatr Emerg Care. Oct 1996;12(5):360-4. [Medline].
Bush SP. Black widow spider envenomation mimicking cholecystitis. Am J Emerg Med. May 1999;17(3):315. [Medline].
Allen RC, Norris RL. Delayed use of widow spider antivenin. Ann Emerg Med. Sep 1995;26(3):393-4. [Medline].
Cohen J, Bush S. Case report: compartment syndrome after a suspected black widow spider bite. Ann Emerg Med. Apr 2005;45(4):414-6. [Medline].
Bush SP, Naftel J. Injection of a whole black widow spider. Ann Emerg Med. Apr 1996;27(4):532-3. [Medline].