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Physiology of Stingray Venom

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Effects of Stingray Envenomation

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Effects of Stingray Envenomation: Symptoms/Effects


            On average, about 750 to 2,000 human injuries caused by stingrays occur in the United States each year. (Diaz, 2008).  In a clinical review of 119 cases of stings in the California area over an 8-year period, the average age of the victims was 28.3 years with a range from 9 to 68 years of age.  Males were also most predominantly affected, making up 96 of the 119 patients.  Furthermore, 94% of these injuries were in the patients’ lower extremities mainly due to the accidental stepping of rays resting along the ocean floor (Clark et al., 2007). Lethal cases are extremely rare, such as the death of Steve Irwin after getting stung in his chest, however when it does occur, it is mainly due to the stinging of vital organs(Barbaro et al., 2007).

After getting stung, the pain typically peaks at 30 to 60 minutes following the injury and it radiates centrally, lasting around 48 hours  (Magalhaes et al., 2006).  The first phase of envenomation involves erythema and edema of the skin and tissues respectively.  Such intense inflammation in humans suggests that the stingray venom affects the extracellular matrix of cells(Barbaro et al., 2007).  This phase is followed by central necrosis of the fat and muscle causing tissue flabbiness and the formation of a pink ulcer about 96 hours after the sting (Magalhaes et al., 2008; Germain et al., 2000).  Below is an image of this underlying tissue necrosis. 


Figure 4: Photomicrograph (x150) of epidermal necrosis expansion near the puncture site. Used with permission from (Germain et al., 2000).


Further effects of stingray stings include fever, paresthesia, dizziness, nausea, vomiting, salivation, diarrhea, abdominal cramps, sweating, muscle fasciculations, and convulsions (Haddad Junior et al., 2003; Dehghani et al., 2010; Russell et al., 1958).  More serious effects deal with limb paralysis, hypotension, respiratory depression, and cardiac arrhythmias (Evans and Davies, 1996; Germain et al., 2000; Dehghani et al., 2010).  More information on cardiovascular effects are located on the similarly-named page.  Below is a table detailing the percentages of patients that exhibited certain symptoms following stingray injuries.

 

Table 3: Percent of signs and symptoms exhibited by 84 individuals in freshwater stingray injuries. Adapted from (Haddad Junior et al., 2003).

Signs and symptoms N (%)
Intense pain 100
Erythema 100
Edema 100
Skin necrosis 90.4
Ulcers 90.4
Systemic manifestations 80.9


Although fatalities resulting from stingray injuries are rare, there are common symptoms that may result in death.  These effects include delayed wound infections with gangrene, botulism, septic shock, airway compromise, and thoracic trauma.  (Diaz, 2008).  In most cases, complete healing without functional loss occurs about 2 months after the initial injury (Germain et al., 2000)

The serrated spines of stingrays oftentimes causes damage to underlying soft tissue as it is retracted from the wound (Evans and Davies, 1996).  Such mechanical impact can oftentimes cause more damage than the venom itself, delaying the healing process. Infections and cellulitis from such lacerations are not uncommon among stingray injuries (Dehghani et al., 2009).

Differences:
Freshwater and marine stingray injuries can sometimes differ in their effects on the victim.  The more severe reactions tend to occur with freshwater injuries.   Freshwater tissue extracts have been shown to cause more prominent necrosis and an intense inflammatory reaction at the injection point.  Ulcers and nocicpeption are also more prominent in freshwater stingray injuries. Below is a graph comparing nociception responses in mice caused by freshwater and marine stingray tissue extracts (Barbaro et al., 2007)


Figure 4 - Nociception in mice in response to Potamotrygon falkneri (freshwater) and Dasyatis guttata (marine) tissue injection. PBS was used as the control. Reactivity is the time it took the mice to bite or lick the injured area in 30 minutes. Adapted from (Barbaro et al., 2007).

 

 

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