​Patients often present to the primary care clinic when faced with envenomation, bites and stings. In many cases, prompt action is of the essence when it comes to long-term patient outcomes. Singapore General Hospital outlines the key points for general practitioners to note in the management of potential wounds inflicted by local sea and land creatures.

INTRODUCTION

Though envenomation, bites and stings are frequently encountered in the emergency department setting, patients may first choose to visit a nearby neighbourhood clinic.

Hence, it is important for general practitioners (GPs) to get to know some of the common creatures found in Singapore’s ecosystem, and what to do when a patient who has crossed paths with them requires medical attention.

Managing Envenomation, Bites and Stings by Sea Creatures

The sea creatures listed below can be found at our local beaches, including at Sentosa.

When presented with envenomation, bites or stings by these creatures, the general principles would be to pour vinegar over the affected site followed by warm water immersion at 40 to 45°C. Ensure that the water temperature is not too hot, or the patient might end up getting scalded.

Read on for more tips on primary care management of envenomation, bites or stings by sea creatures.

JELLYFISH

  • Pour vinegar on the wound

    • This inactivates undischarged nematocysts, also known as barb used for prey capture, defence and locomotion

  • Remove embedded tentacular material with forceps

  • Warm water immersion afterwards

  • Consider analgesia, antihistamines or hydrocortisone

  • Update tetanus immunisation status if not already done

  • Consider antibiotics if the wound appears macerated or grossly contaminated

    • Cover for vibrio species or aeromonas (i.e., doxycycline)

  • If an anaphylactic reaction occurs, treat with adrenaline

  • Evacuate immediately if there is severe toxicity (systemic signs and symptoms)

  • There is no role for urine

  • Symptoms can recur intermittently over days (e.g., Morbakka species causing Irukandji syndrome)

Tips for patients

  • Notify authorities (National Parks Board [NParks] or beach patrol officers if in Sentosa)

  • Locations with box jellyfish sightings:

    • Palawan Beach (Sentosa)

    • ONE°15 Marina Sentosa Cove

    • Lazarus Island

    • Pulau Seringat

    • Tuas

    • East Coast Park

STONEFISH / STINGRAYS

  • Warm water immersion

    • 40 to 45°C water x 20 minutes x 3 cycles (with 10 minutes rest)

    • Consider soaking both the affected and unaffected limbs as well so that the patient can gauge if the temperature of the warm water immersion is tolerable

    • Analgesia must not cause sedation or mask the patient's perception of pain to avoid scalding

    • Serious iatrogenic thermal injuries have been sustained from warm water immersion therapy, some even requiring plastic reconstructive surgery

SEA URCHINS

  • Remove as many spines as possible (use a magnifying glass)

  • Warm water immersion

  • Consider vinegar to dissolve spines (calcium carbonate)

  • Update tetanus immunisation status

  • Monitor for infection or foreign body granuloma reaction

  • May require referral to Orthopaedic Surgery for punch biopsy or surgical debridement if there are prolonged symptoms from retained spines


Managing Envenomation, Bites and Stings by Land Creatures

This section will cover a broad range of animals and creatures, some more commonly encountered than others.

It will also explore when it is necessary to consider wound management and rabies treatment. An interesting point to note is that while all dogs and cats (including strays) in Singapore have been declared rabies-free by the National Environment Agency, bats are an exception.

For wounds, do note to avoid primary closure.

BEES

  • Consider antihistamines and update tetanus immunisation status

  • Treat anaphylaxis with intramuscular adrenaline

    • Toxic dose: 4-8 stings per kg of body weight

    • A patient can experience anaphylaxis and/or death with only one sting

  • Scrape off stingers with the edge of a card (e.g., credit card)

    • Do not use fingers, as this may squeeze the venom or break the venom sac

    • Beware of stingers hidden in the hairline

  • Evacuate (immediately to the nearest hospital facility) if there are multiple stings or systemic toxicity

Tips for patients

  • Gently brush off the bee or move the body part where it lands

    • Bees like to land on skin to drink sweat

    • Do not swat – this may cause the bee to sting or release alarm pheromones

    • Cover the face and run straight, against the wind

    • Do not flail arms or swat bees

    • Do not submerge in water

SPIDERS

  • Painful, venomous but not lethal

  • Tarantulas have urticating hairs

    • Can be embedded in the cornea causing ‘tarantula keratitis’

Tips for patients

  • Wear an eye shield for your own protection in the clinic

  • Avoid too close proximity to tarantulas if rearing these as pets

SCORPIONS

  • Painful, venomous but not lethal 

SNAKES

  • If the bitten limb has not been immobilised, consider splinting to immobilise the limb and instructing the patient not to walk on the bitten limb

  • Monitor for signs of envenomation requiring antivenom:

    • Local – mark out edges of swelling, monitor for compartment syndrome

    • Neurological – ptosis, bulbar palsy, dysarthria, dysphagia

    • Cardiovascular – monitor pulses, blood pressure and heart rate

    • Haematological – ecchymoses, bruising

    • Rhabdomyolysis

  • Evacuate to the hospital with antivenom if necessary or if high suspicion

  • Antivenom

    • Polyvalent antivenom – risk of anaphylaxis due to higher protein load

    • Choice between antivenom for haematotoxin vs neurotoxin

Tips for patients

  • Maintain safety

    • Call NParks at 1800-476-1600 as per the advisories on www.nparks.gov.sg, or the ACRES Wildlife Rescue hotline at 9783 7782

  • Identify the snake safely with photos

    • Patterns – Download the SG Snakes app by Wildlife Reserves Singapore from https://appadvice.com/app/sg-snakes/669392463.amp

​Commonly encountered snakes 

​Non-venomous

​Venomous​

  • Common wolf snake
  • Reticulated python
  • Black equatorial spitting cobra (most venomous; aims for eyes and face to cause maximum pain)
  • King cobra
  • Oriental whip snake (mildly venomous)
  • Banded krait
  • Mangrove pit viper
  • Wagler’s pit viper
  • Malayan blue coral snake
  • Paradise tree snake (mildly venomous)


  • Immobilise, splint, and do not walk on the bitten limb

    • Keep the bitten limb below the level of the heart

    • Do not tourniquet, apply suction or ice, or debride

OTTERS

  • Wound care – avoid primary closure (unless on the face, though there is a high risk of infection)

  • Antimicrobial prophylaxis

    • Augmentin (ciprofloxacin and clindamycin if there is a penicillin allergy)

    • Tetanus

    • Consider referral to the Emergency Department or an infectious diseases physician for consideration of rabies treatment (although NParks conducts regular rabies screening for large otter families, such as those in Bishan and Marina Bay)

MACAQUES (MONKEYS)

  • Acyclovir 800 mg orally 5 times a day, or valacyclovir every 8 hours for 14 days for B virus prophylaxis

  • Rabies vaccination or immunoglobin per Table 1

  • Update tetanus immunisation status

  • Consider antibiotics

BATS

  • Clean wound with copious water and soap

    • Bat scratches are ‘better felt than seen’ as they are not always obvious

    • They may not bleed or have obvious signs

  • Rabies risk (refer to Table 1)

    • Uniformly fatal if symptoms develop

    • The infected animal may not show rabid symptoms

    • Post-exposure prophylaxis:

      • For individuals who have been previously vaccinated

        • Rabies vaccine at days 0 and 3

        • The deltoid region should be used

        • Avoid the gluteal area as immune response may be reduced

      • For individuals with no previous vaccination

        • Full dose of human rabies immunoglobulin (HRIG) infiltrated around wound if anatomically feasible

        • Important to avoid the gluteal area due to risk of sciatic nerve damage

        • Give in anterolateral thigh

        • Do not administer rabies vaccine and immunoglobulin at the same site or in the same syringe

        • Immunisation schedule

          • Immunocompetent patients: days 0, 3, 7 and 14

          • Immunocompromised patients: days 0, 3, 7, 14 and 28


When wound care or rabies treatment is needed - SGH

Table 1


CONCLUSION

In summary, while bites and stings from wild animals and creatures are not very commonly encountered in the GP setting, it is important to have knowledge of what creatures exist that can cause potential harm and the treatments to be instituted, as this can change long-term patient outcomes.

There are many resources available to assist medical providers in the event of such encounters, such as the NParks hotline and website, ACRES Wildlife Rescue hotline and SG Snakes identification app.


Dr Ng Mingwei graduated from the Yong Loo Lin School of Medicine, National University of Singapore (NUS) and completed his training in Emergency Medicine in 2021. He is currently pursuing his sub-specialty interest in toxicology as a Fellow with the SingHealth Toxicology Service and recently completed his post-graduate diploma in Medical Toxicology with Cardiff University.


Dr Jeevan Raaj graduated from the National University of Singapore Yong Loo Lin School of Medicine in 2012 and subsequently completed his training in Emergency Medicine in 2020. His areas of interest are in emergency observational medicine, emergency critical care as well as medical education.


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