A Severe Accident Caused by an Ocellate River Stingray (Potamotrygon motoro) in Central Brazil: How Well Do We Really Understand Stingray Venom Chemistry, Envenomation, and Therapeutics?

Abstract

Freshwater stingrays cause many serious human injuries, but identification of the offending species is uncommon. The present case involved a large freshwater stingray, Potamotrygon motoro (Chondrichthyes: Potamotrygonidae), in the Araguaia River in Tocantins, Brazil. Appropriate first aid was administered within ~15 min, except that an ice pack was applied. Analgesics provided no pain relief, although hot compresses did. Ciprofloxacin therapy commenced after ~18 h and continued seven days. Then antibiotic was suspended; however, after two more days and additional tests, cephalosporin therapy was initiated, and proved successful. Pain worsened despite increasingly powerful analgesics, until debridement of the wound was performed after one month. The wound finally closed ~70 days after the accident, but the patient continued to have problems wearing shoes even eight months later. Chemistry and pharmacology of Potamotrygon venom and mucus, and clinical management of freshwater stingray envenomations are reviewed in light of the present case. Bacterial infections of stingray puncture wounds may account for more long-term morbidity than stingray venom. Simultaneous prophylactic use of multiple antibiotics is recommended for all but the most superficial stingray wounds. Distinguishing relative contributions of venom, mucus, and bacteria will require careful genomic and transcriptomic investigations of stingray tissues and contaminating bacteria.

Transcriptomic Characterization of the South American Freshwater Stingray Potamotrygon motoro Venom Apparatus

“…Afterwards, purification and isolation of mRNA with poly(A) tails was performed using Oligo-(dT)-attached magnetic beads, and the obtained mRNA was proceeded to Illumina cDNA library construction and sequencing through Illumina HiSeq2000 platform (Illumina, San Diego, CA, USA) at BGI-Tech (BGI, Shenzhen, Guangdong, China). The lack of a well-defined gland structure makes tissue extraction challenging and thus not all the molecules found may be representative of the stingray venom [59,60].…”

Delayed healthcare and secondary infections following freshwater stingray injuries: risk factors for a poorly understood health issue in the Amazon

“…Trimethoprim/sulfamethoxazole, ciprofloxacin, or tetracycline have been suggested for the treatment of fish wound infections 36 . Treatment failure has previously been reported in Central Brazil for ciprofloxacin 21 and in California, United States, regarding trimethoprim/sulfamethoxazole 42 for patients presenting with stingray wound infections.…”

“…Since reporting of work-related injuries in Brazil is compulsory, stingray injuries, especially those that progress to complications such as secondary infection, are more likely to be reported than accidents occurring within other groups, and reporting bias may have elevated this association. However, specific hygiene behaviors, including the use of homemade medicines and environmental workplace exposures predisposing to secondary infection, cannot be discarded 21,22,40 .…”

“…In the Brazilian Amazon, while stingray injuries have been associated with bacterial infection and necrosis, the complication frequency rate is not well known. The most severe cases associated with secondary bacterial infections required antibacterial treatment and a prolonged recovery 20 with longterm disabilities 21 , all associated with social and economic losses. Necrotizing fasciitis due to Vibrio alginolyticus (marine stingrays) and Aeromonas hydrophila (freshwater stingrays) 22,23 , tetanus 24 , and invasive mycoses 25 secondary to stingray injuries, as well as other severe infections, seem to be less common complications.…”

Stingray venom activates IL-33 producing cardiomyocytes, but not mast cell, to promote acute neutrophil-mediated injury

“…In some cases, subsequent bacterial infection may contribute to sequelae. The use of analgesics such as tramadol hydrochloride, carbamazepine, thiamine, non-steroidal anti-inflammatory agents like ketoprofen, or synthetic opioid like meperidine, concomitantly with antibiotics administration, is ineffective to treat the pain or to prevent the development of necrosis 10 .…”