Sting Ray Injuries
While sailing in the Sea of Cortez, I have been surprised at the number of cruisers who have been stung by stingrays. Since there seems to be a variety of treatment opinions, I thought I would present the latest information regarding stingrays and stingray injuries. The main source of information on stingray injuries is the text Wilderness Medicine, Management of Wilderness and Environmental Emergencies by Paul S. Auerbach, MD. Out of print is a much smaller, less expensive and lighter-weight text, A Medical Guide to Hazardous Marine Life. Both are excellent references. For those with computer access, there are also several sites available on the web.
Stingrays are the most common group of fishes involved in human envenomations (stings) - over 1500 stings are reported every year. Sometimes referred to as aquatic land-mines, stingrays often lie buried in the sand or even stacked upon one another in shallow areas of water. There are several stingray species found in Baja. The first is the Round Stingray (Urolophus maculatus). This small stingray only grows to 2 feet across, has round pectoral wings and is brownish in color often with dark spots. The Bullseye Stingray (Urolophus concentricus) looks similar to the Round Stingray but has concentric circles and has no fins on the tail. These two species are the most common to be stepped upon as they enjoy shallow sandy or muddy areas of water. For divers, the Diamond Ray (Dasyatis brevis) is often seen buried beneath the sand and is easy to step on with your foot (fin) if you are not looking. Diamond Rays grow to 5 feet across and have been reported to have caused one death in the Sea of Cortez of California. There are two additional stingrays found in the waters of Baja. The uncommon Butterfly Ray (Gymnura marmorata) is often described as a handsome ray with large (up to 5 feet) spotted wings and a small stinger. The Bat Ray (Myliobatis californica), which grows to 6 feet, has a long stinger and a distinctive large raised head.
Stingrays are not aggressive animals. In fact, they are docile creatures that would prefer not be stepped upon. The best way to prevent stings is to adopt the "stingray shuffle." When walking in shallow waters, shuffle your feet along, preferably wearing some sort of footwear, without lifting your feet and stepping down. Another option, if towing your dinghy to shore, is to take one of your oars and gently probe or slide your oar along the ground in front of you. Wearing Tevas, reef walkers or tennis shoes does not eliminate the possibility of stingray injuries. Most stings, in fact, are not through the sole of the foot or shoe but commonly in the ankle, side or top of the foot. Clothing provides little or no protection, as stingray spines (stingers) have been know to penetrate neoprene, leather or rubber.
There are two aspects of a stingray injury. The first is direct trauma from the stingray spine or stinger. The stinger (usually one, but some species have up to four) is a modified fin spine located at the base of the ray's tail. The spine has rows of incredibly sharp one-way barbs resembling the serrated blade of a knife. The spine is bone-hard, has a pointed end, and can be up to fourteen inches long. When stepped on, the stingray flips its tail forward or sometimes side-to-side when reflexively stinging. This produces the typical injury pattern on the top of the foot or in the lower leg. More severe injuries occur when the spine enters the chest or abdomen. Deaths have been reported from injuries to vital organs such as the heart or from lacerations of major arteries. In addition to these injuries, the spine and/or the sheath are often left embedded into the victim, complicating infections secondary to the presence of a foreign body under the skin.
The second cause of injury occurs as a result of evenomation from the stingray. The entire spine or stinger is covered with a sheath, which discharges venom when ruptured. The venom or toxin is a heat-labile (degraded by heating) protein for which no anti-venom exists. On the off chance that you are worried about the well being of the stingray, they are able to regenerate broken spines, similar to how we regenerate our fingernails. One can often find old stingers on the beach among the shells and they make great letter openers.
Stingray injuries can be fairly serious depending upon the location of the sting and the amount of venom, barbs, mucous and spine that are left in the wound. The wound may be solely an uncomplicated puncture wound or a significant laceration due to the incredibly sharp nature of the spines. Envenomations cause immediate, intense pain at the site of the injury, often described as "the worst pain ever felt." The pain may last for up to 48 hours but typically peaks at 30-60 minutes. The wound will often initially look blue or dusky in color and then may become bright red. Swelling and bleeding occurs. Common symptoms caused by the venom include dizziness, headache, weakness, sweats, nausea/vomiting, diarrhea, headache, muscle cramps, fainting and anxiety. Necrosis (tissue death) and infection are common problems following envenomations.
First aid treatment is the same regardless of the species of stingray. The rate of recovery from a stingray injury/evenomation depends upon rapid and thorough medical treatment. Deep wounds and wounds to the chest and abdomen need immediate treatment at a medical facility.
- The wound should be immediately irrigated with fresh, clean water to remove the venom. Ideally, the water should be sterile, but tap water will work. Saltwater should be used only as a last resort due to the presence of bacteria in seawater. Contrary to folklore, vinegar and urine are not effective treatments for stingray injuries.
- Manually remove as much foreign material as possible; this will decrease the chance of persistent infection. Immersion in hot water should not be delayed in order to meticulously remove material, but obvious foreign matter can be quickly extracted.
- Immersion in hot water will greatly decrease the pain. The water should be as hot as possible without causing burns (less than 114-115 °F), and the injury should be immersed for 30-90 minutes. The water should be changed frequently to maintain the temperature. While the wound is soaking, continue to remove any foreign material in the wound. In the absence of hot water, hot compresses or hot sand may be useful. It is essential, however, that the wound be thoroughly irrigated to remove any sand after treatment. While there are several theories as to why hot water decreases pain, the exact mechanism is unknown. Denaturing the protein toxin has been postulated, but studies show that it takes temperatures over 120°F to deactivate the toxin.
- Pain can be treated with oral pain medications, or, if you are trained and carry a local injectable anesthetic such as lidocaine (Xylocaine®) or bupivacaine (Marcaine®), infiltration around the wound will relieve pain and allow easier removal of foreign matter. The wounds usually continue to be painful for up to 48 hours.
- After soaking in hot water, apply a sterile dressing over the wound and change daily. Elevation of the wounded area is recommended and staying out of seawater is essential. Since seawater is contaminated with bacteria, most authorities do not recommend suturing (stitching) the laceration. If sutures are placed, it is recommended that the wound be closed loosely, allowing space for infection to drain if it occurs.
- Bacterial infections are very common with stingray injuries, and most experts recommend at least five days of prophylactic antibiotic treatment. The most common infection is caused by either Staphylococcus aureus or Streptococcus species, both common bacteria found on skin. In addition, salt water is usually contaminated with other bacteria, especially Vibrio species. Antibiotics chosen for treatment or prophylaxis should be active against all three of these species. Vibrio is best treated with Ciprofloxacin, although trimethoprim/sulfamethoxazole (Bactrim® or Septra®) and doxycycline are good alternatives. Ciprofloxacin and doxycycline are both contraindicated in children, so trimethoprim/sulfamethoxazole should be used. Coverage of Staphylococcus and Streptococcus by these drugs is variable, and addition of dicloxacillin or cephalexin/cephradine is recommended, especially if the would appears infected or is not improving. See table below.
- Definitive treatment should be sought as soon as possible. Wounds that are not healing or in which infection is not improving in spite of antibiotics need immediate medical attention. Retained foreign material (spine, sheath, or clothing) should be considered in all non-healing wounds. Often x-rays, ultrasound or an MRI are needed to find these foreign materials.
Drug Usual Adult Dose Coverage and Comments
- Ciprofloxacin (Cipro®) 500 mg orally twice a day for five days, Covers Vibrio and Staphylococcus aureus. Not as good for Streptococcus.
- Trimethoprim/Sulfamethoxazole(Bactrim® or Septra®) One double strength (DS) tablet orally twice a day for five days Good coverage for Vibrio but some resistance recently reported. Staphylococcus and Streptococcus coverage not optimal.
- Doxycycline 100 mg orally twice a day for five days Good coverage for Vibrio. Staphylococcus and Streptococcus coverage not optimal
- Dicloxacillin 500 mg orally four times a day for five days Covers Staphylococcus and Streptococcus. Not active against Vibrio.
- Cephalexin (Keflex®) or Cephradine (Velosef®) 500 mg orally four times a day for five days Covers Staphylococcus and Streptococcus. Not active against Vibrio.
The above should only be used as a guide and in collaboration with your medical provider who understands the unique situation of a cruiser, your medical history, medicines you are taking and your allergies to medicines. Remember that many medications need dosage adjustments for age (young or old), kidney or liver disease. In addition, some medications are not appropriate for children or pregnant women. We cannot emphasize the importance of reviewing this list with your medical provider.
Article contributed by
Jan Loomis with significant contributions from James Bryan, MD, PhD and Steven Webster, Senior Biologist for the Monterey Bay Aquarium.
Jan Loomis, RN, is an Adjunct Assistant Professor with the Department of Emergency Medicine and the former Coordinator of the International Travel Health Services at Oregon Health Sciences University in Portland, Oregon. She has been sailing for most of her life.
Another Treatment Possibility
From Shirley Daley 10/18/07 - I was just looking at the website & it reminded me that a few weeks ago I was unfortunate enough to be "stung" by a Stingray. It was, as noted, incredibly painful but the soaking in very hot water (unfortunately 1/2hr. later) did wonders eventually. What really helped, was, somewhat later, the use of a Snakebite kit syringe. I was in the process of explaining the stingray shuffle to friends when I was "got". These same friends had their friends bring down Snakebite kits for all of us & just last week under very similar circumstances another friend was 'stung & within 2mins. the syringe was used & although the pain was initially excruciating, it was, after 3 extractions of venom, almost immediately pain free. What a find!!! The kits were purchased at an REI sporting goods store for around $15 & I would suggest, be a very useful addition to cruisers medical kits.