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  2. Mexico and Central America
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  4. Pit Vipers
  5. Clinical entry: Sistrurus sp.

Clinic: Sistrurus sp.

Examine for venom effects

Autopharmacological effects

  • Nausea, vomiting
  • Sweating
  • Urticaria, angiooedema
  • Arterial hypotension / hypovolaemic shock (transient, recurrent; immediate; delayed (CLS))
  • Diarrhoea
  • Bronchospasm 

Local Effects

  • Pain
  • Tender local (spreading) swelling
  • Blistering
  • Lymphangiopathy and lymphadenopathy
  • Necrotic skin

Haematological effects 

  • Clotting disturbances:
    • Bleeding from the fang marks and from injuries, in particular ones that are not located in the region in which venom application occurred.
    • Bleeding into the skin (ecchymosis, petechiae)
    • Gingival bleeding, bleeding from the nose, conjunctiva, haematemeis, bleeding per rectum, including melaena, haematuria, haemoptysis.
    • Oliguria, anuria (VICC / AKI)
  • Bleeding and/or haemolytic anaemia:
    • Arterial hypotension (haemorrhagic shock)
    • Acute abdomen (intra-abdominal bleeding!)
    • Loin pain/renal bed sensitive to percussion (ischaemia, renal haemorrhage!)
    • Local neurological signs, meningism, coma (intracranial bleeding!)
    • Pale sclera (bleeding, haemolysis!)
    • Oliguria, anuria (arterial hypotension / AKI!)

Species-specific envenoming pattern

The assessment of the envenoming pattern is based on the data from publication in which the identification of the snakes is clearly specified and in accordance with accepted criteria.

  

Autopharma-
cological effects1

 Local effects2 Haematological effects
Bleeding3  Coagulopathy4
Sistrurus sp.         

1Autopharmacological effects

Not mentioned in the available case reports.

2Local effects

Sistrurus miliarius
Local swelling with ecchymosis 3.5 h after the bite (Ahlstrom et al. 1991).
Necrosis (Zabawa 2024).

Haematological effects

3Bleeding
Not mentioned in the available case reports.

4Coagulopathy
Type of haemostatic defect 
Defibrin(ogen)ation (Kitchens 1992, pers. comm.).

Case fatality rate

Rarely life-threatening or ultimately fatal (Wasko et al. 2021).

Clinical management

See also Clinical Management: North America

for advice on post-First Aid measures, diagnosis (clinical, laboratory) and treatment (supportive, antivenom).

First Aid

Release of any type of tourniquet follow link above.

Local treatment

Pain control
Tetanus prophylaxis
Standard wound care
WHO (2010) 

Systemic supportive treatment

A general understanding of emergency medicine is required, or can be found in emergency medicine guidelines, e.g. ABCDE approach, WHO-ICRC Basic Emergency Care.

Follow SAMPLE & ABCDE ApproAch

Obey sistrurus sp. - specific features

see

  • 'Species-specific envenoming pattern above'

and

  • Evidence-informed unified treatment algorithm for pit viper snakebite management in the US (Lavonas et al. 2011)
  • Brandehoff et al. (2026)

Key issues

See footnotes above.

Specific treatment (antivenoms)

References

see also references in section 'species specific evidence' (below). 

  • Wasko DK, Bullard SG, Beauvais TF. Epidemiology of Eastern Massasauga (Sistrurus catenatus) Snakebites in the Great Lakes States, 1800-2015. Wilderness Environ Med. 2021 Sep;32(3):308-314. Epub 2021 Jun 23. PMID: 34172376. https://doi.org/10.1016/j.wem.2021.03.011
  • WHO-ICRC Basic Emergency Care: approach tothe acutely ill and injured (2018)
    https://www.who.int/publications-detail-redirect/basic-emergency-care-approach-to-the-acutely-ill-and-injured
  • WHO ABCDE Approach
    https://cdn.who.int/media/docs/default-source/integrated-health-services-(ihs)/csy/bec-quick-cards/becp-edu29-pdf-en-finl.pdf?sfvrsn=2532d61b_2
  • WHO (2010) Wound and lymphoedema management. WHO/HTM/NTD/GBUI/20101 I. 2010. https://www.who.int/publications/i/item/9789241599139
  • WHO Snakebite Information and Data Platform
    https://www.who.int/teams/control-of-neglected-tropical-diseases/snakebite-envenoming/snakebite-information-and-data-platform
  • Warrell DA. Venomous and poisonous animals. In: Farrar J, Garcia PJ, Hotez T, Junghanss T, Kang G, Laloo D (eds.). Manson’s tropical diseases. 24th ed. Elsevier; 2023.
  •  Warrell DA, Williams DJ. Clinical aspects of snakebite envenoming and its treatment in low-resource settings. Lancet. 2023 Apr 22;401(10385):1382-1398. PMID: 36931290. https://doi.org/10.1016/s0140-6736(23)00002-8 

Species-specific evidence

Sistrurus miliarius 

USA

  • Ahlstrom et al. (1991)
    1 patient; identification: morphological.
  • King et al. (2012)
    1 patient; identification: morphological.
  • Sequeira and Sequeira (2019)
    1 patient; identification: morphological.
  • Zabawa (2024)
    1 patient; identification: morphological.

Sistrurus catenatus 

  • Hankin et al. (1987)
    1 patient; identification: geographical exclusion criterion.

References

  • Ahlstrom, N. G., W. Luginbuhl, C. C. Tisher (1991) Acute anuric renal failure after pigmy rattlesnake bite. S. med. J. 84: 783-785
  • Hankin, F. M., M. D. Smith, J. A. Penner, D. S. Louis (1987) Eastern massasauga rattlesnake bites. J. Ped. Orth. 7: 201-205
  • 1 King AM, Crim WS, Menke NB, Pizon AF. Pygmy rattlesnake envenomation treated with Crotalidae Polyvalent Immune Fab Antivenom. Toxicon. 2012 Dec 1;60(7):1287-9. Epub 2012 Aug 30. PMID: 22963729. https://doi.org/10.1016/j.toxicon.2012.08.007
  • Sequeira MJ, Sequeira AJ. What's eating you? dusky pigmy rattlesnake envenomation and management. Cutis. 2019 Nov;104(5):284-287. PMID: 31886787.
  • Zabawa LM. Western Pygmy Rattlesnake Envenomation and Bite Management. Cutis. 2024 Oct;114(4):117-119. PMID: 39621570. https://doi.org/10.12788/cutis.1111