Stingray Envenomation 

Updated: May 04, 2017
Author: John L Meade, MD; Chief Editor: Joe Alcock, MD, MS 

Overview

Background

Stingrays (ie, elasmobranchs) are bottom-dwelling cartilaginous fish that have a flattened body, one or more stout spines on the tail, gill slits on the lower surface of the head, teeth modified into 2 large crushing plates, and no dorsal fin. They are not aggressive toward humans; however, injuries from these animals are very common. Stingrays are shown in the images below.

Stingray. Stingray.
Stingray. Stingray.

Stingrays from the northern hemisphere make up the family Dasyatidae. These fish are marine creatures (ie, live in salt water) but also have been found in brackish waters and bays. Another ray family (Potamotrygonidae)[1] contains poisonous species known as freshwater stingrays. These freshwater stingrays live in lakes and rivers of South America.

See Deadly Sea Envenomations, a Critical Images slideshow, to help make an accurate diagnosis.

Also see Cutaneous Manifestations Following Exposures to Marine Life.

Prognosis

Stingray injuries (eg, puncture wounds, lacerations, envenomations) tend to have good outcomes. If patients do not develop infection or other complications, they can expect to have minimal pain in 24-48 hours and healing within 1-2 weeks.

Patient Education

Following is an example of discharge instructions that could be given to patients after treatment of stingray injuries.

Because so many areas of water are nearby, many types of injuries associated with being in or near the water are encountered. These injuries may occur while fishing, walking on the beach, playing in the surf, diving, or working with a home aquarium.

Stingrays often cause lacerations and puncture wounds when the tail whips up and thrusts its barbed spine into the victim, depositing venom (poison). The pain is severe immediately and worsens over the next hour. The pain may last 48 hours. Although rare, deaths have occurred from stingray injuries.

As soon as possible, the wound should be soaked for 30-90 minutes in very hot water (as hot as can be endured without causing burns). The heat inactivates the poison and dramatically relieves the pain. The physician may prescribe pain medication. Also, because the risk of infection is very high, antibiotics are given to prevent infection.

Despite the best of care, any wound can develop infection or other complications. If any of the following occur, it is recommended that patients call their own doctor, the referral physician, or clinic (If a physician cannot be contacted, return to the ED is advised.):

  • Wound drainage increases, shows pus, or develops a foul odor

  • Wound bleeds heavily

  • Wound becomes more sore or swollen

  • Wound develops increasing redness, or red streaks develop

  • A fever develops

  • Wound does not appear to be healing properly

  • Any other new or worsening symptoms that are of concern

For patient education resources, see the Bites and Stings Center, as well as Stingray Injury.

 

Presentation

History

Stingrays commonly are found lying half-buried in the sand or mud of coastal temperate areas.

Injuries tend to occur when an unsuspecting person steps on the fish, causing the animal to reflexively strike the person with its defensive mechanism.

The stingray's tail has one or more barbed stingers and two ventrolateral venom-containing grooves that are encased in an integumentary sheath. The tail is thrust into the victim, usually in the foot or lower leg, producing a deep jagged laceration from the serrated spine(s). A stingray spine is shown below.

Spine removed from stingray injury. Image courtesy Spine removed from stingray injury. Image courtesy of Scott Plantz, MD.

The stinger apparatus then injects a protein-based toxin into the wound, causing immediate intense (even excruciating) pain in the victim. Injury may occur without envenomation because many stingrays lose or tear the integumentary sheath covering the venom glands.

This subject has taken on worldwide interest due to the unfortunate death of the celebrity wildlife naturalist Steve Irwin (also known as "The Crocodile Hunter") on September 4, 2006. Irwin was filming a documentary on stingrays in Queensland, Australia, when he reportedly suffered a puncture wound of the heart from a stingray barb. He died on the scene. This is a very rare injury since most stingray puncture wounds occur on the extremities and are superficial.

Physical Examination

The wound may bleed freely and the patient may have systemic symptoms, including the following:

  • Syncope

  • Nausea

  • Vomiting

  • Diarrhea

  • Diaphoresis

  • Muscle cramps

  • Fasciculations

  • Abdominal pain

  • Seizures

  • Hypotension

Puncture wounds can cause injury to large vessels, and exsanguination following laceration of lower extremity arteries has been reported. Pseudoaneurysm of the superficial femoral artery has been reported following stingray envenomation.[2]

Stringray wounds are shown in the images below.

Typical stingray puncture wound on a foot, approxi Typical stingray puncture wound on a foot, approximately 60 minutes after injury. Photo by John L. Meade, MD.
Stingray barb in forearm. Photo by John L. Meade, Stingray barb in forearm. Photo by John L. Meade, MD.
 

DDx

 

Workup

Laboratory Studies

No laboratory studies are indicated in the usual case of stingray injury.

Imaging Studies

Plain radiography should generally be used to obtain images of the injured area in at least 2 planes. Plain radiography is useful to rule out the presence of any foreign bodies, such as retained components of the barb mechanism, as well as to differentiate injuries caused by some other object (eg, sharp object stepped on in the water, causing a retained foreign body).[3]

A stingray barb is shown in the radiograph below.

Stingray barb broken off in ring finger. Photo by Stingray barb broken off in ring finger. Photo by John L. Meade, MD.
 

Treatment

Prehospital Care

As soon as possible, immerse the affected body part in very hot water (as hot as the patient can tolerate without actually getting burned) or apply a hot pack to the affected body part. Heat rapidly decreases the patient's pain, presumably due to the direct effect on the poison.

Emergency Department Care

If a patient has demonstrated any sign of systemic effect, it should be addressed quickly.

No specific antidote is available, and supportive care is recommended, including use of analgesics.

An easy and important initial treatment that can be started (sometimes at the scene of the injury) is immersion of the injured extremity in hot water (preferably 110-115°F). The water should be as hot as the patient can tolerate but should not cause burns. The water should be exchanged for more hot water as it cools, for an immersion duration of 30-90 minutes.

Very little has been written about the toxin left in wounds after a stingray injury. It is known that the stingray toxin is a protein and is very sensitive to heat. The patient should obtain very rapid symptomatic improvement with heat as the poison denatures and becomes neutralized. Some thought exists that the protein does not truly denature but that some sort of gateway effect occurs on the nerve conduction. Whatever the mechanism, heat is a rapid, effective treatment to reduce pain almost instantaneously.

In addition, some practitioners also infiltrate the wound with a local anesthetic, such as lidocaine (lignocaine)[4] or the longer-acting bupivacaine. Oral or parenteral narcotics may also be given if the patient is suffering severe pain. The effectiveness of hot water immersion may eliminate the need for local anesthetic infiltration.

After the toxin has been deactivated by the hot water, attention to local wound care should begin because it is not uncommon for part of the stinging apparatus to break off in the wound.

Obtain a plain radiographic image of the injured area to look for retained barbs or other foreign material. Explore the wound thoroughly and irrigate it. Perform any necessary debridement.[5]

Remove any foreign body from the wounds, including the spine and sheath from the stingray stinger (if present), as well as any dirt or sand.

As with other potentially contaminated wounds, consider allowing the wound to heal without closure. Because most of the wounds are small, this usually is not an issue. If the wound is very large or gaping, consider loose primary closure.

Address the patient's tetanus immunization status and administer a booster as needed.

Prevention

When stepped on, the stingray reflexively strikes out, causing the injury to the person who stepped on it. Advise patients to walk in the shallow areas of the beach with a shuffling gait. This is effective in causing stingrays to move away and help decrease the possibility of accidentally stepping on a stingray.

Long-Term Monitoring

Give patients explicit instructions regarding attention to local wound care and advise them to watch for infection. Requesting that the patient seek a wound check in 2-3 days (with a family doctor or at the ED) is not unreasonable.

It is especially vital that the patient understands that for any sign of infection with Vibrio organisms, time is of the essence in returning to the ED for immediate care.

 

Medication

Medication Summary

Infection is not common but, if it occurs, is likely to result in high morbidity because of injury location and the possible infecting agents in the water environment. Staphylococci and streptococci remain the most common infecting agents and must not be ignored. However, pathogens of specific concern to such envenomations are Vibrio species in saltwater and Aeromonas species in freshwater. Optimal coverage should include staphylococci, streptococci, and pathogens expected in the involved water (freshwater or saltwater). Such antibiotics include quinolones (eg, ciprofloxacin, levofloxacin), doxycycline, trimethoprim/sulfamethoxazole (Bactrim, Septra), cefuroxime or other late-generation cephalosporins, an aminoglycoside, or chloramphenicol.

As one study[6] showed a significant number of patients returning to the ED with wound infections when prophylactic antibiotics were not administered at initial presentation, many physicians choose to treat the wounds associated with stingray envenomations prophylactically with a short course (~5 d) of oral antibiotics.

Prescribing oral narcotics for patients to use as needed upon discharge is appropriate.

Antibiotics

Class Summary

Antibiotics are used in the treatment of uncomplicated infections and wound prophylaxis. Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Levofloxacin (Levaquin)

Levofloxacin is first-line treatment for infections caused by Vibrio species found in saltwater. It is indicated for Staphylococcus aureus and infections caused by multidrug resistant gram-negative organisms.

Cefixime (Suprax)

By binding to one or more of the penicillin binding proteins, cefixime arrests bacterial cell wall synthesis and inhibits bacterial growth. It is an advanced-generation cephalosporin.Its advantages include a once-per-day dosing schedule and broad spectrum. A disadvantage is relatively high cost.

Cephalexin (Keflex)

Cephalexin is a first-generation cephalosporin, which is usually effective against Staphylococcus and Streptococcus species. It is inexpensive and readily available, but it has no real efficacy against Vibrio species.

Doxycycline (Bio-Tab, Doryx, Vibramycin)

Doxycycline inhibits protein synthesis and, thus, bacterial growth, by binding to 30S and, possibly, 50S ribosomal subunits of susceptible bacteria. It covers Vibrio species well, although coverage is not as good for Staphylococcus and Streptococcus species. Generic versions are inexpensive.

Trimethoprim and sulfamethoxazole (TMP-SMZ, Bactrim, Septra)

This combination inhibits bacterial growth by inhibiting the synthesis of dihydrofolic acid. It is an inexpensive combination agent that covers Vibrio and some Staphylococcus and Streptococcus species.

As with doxycycline, many individuals can develop photosensitive skin rashes while on the medication. (This is important if the patient is on vacation or lives at the beach and is likely to get significant sun exposure while on the medication.)