CHAPTER 13

Numerous species of fish are capable of inflicting painful or even dangerous stings by means of dorsal or caudal spines provided with complex venom glands.

In warmer waters species of stingray, scorpion fish, catfish, rabbit fish, stonefish and stargazers are potentially dangerous.

Fish stings usually present with painful lacerations or punctured wounds.

Intense pain may continue for several hours .

Swelling and erythema around the wounds may simulate an infective cellulitis.

Fig.151a. Dermatitis due to fish toxins

Treatment

1. Hot water:

   This is very effective in treating the stings of weaver fish, as well as those of the stingrays, lionfish and other scorpion fishes . The injured part should be submerged in water as hot as the victim can bear for approximately 30 minuets.

2. Antihistamines

3. Corticosteroids

Severe cases may need topical and systemic corticosteroids .

This phylum includes the jellyfish, hydroids, and other types living mainly in ocean water .

The  most common sites involved are the forearms, feet, thighs and sides of the trunk .

Linear erythematous or urticarial and sometimes hemorrhagic lesions appear at the site of contact with the barbs and tentacles of the organism. Intense pain and sharp stinging sensations are common manifestations.

Nausea , vomiting and abdominal cramps .

Dyspnea and prostration .

Irritability and emotional distress.

Different methods can be used and these depend mainly on removal of the tentacles from the skin .

1. Bathing of the affected area with water and rub with dry sand and scrape the area with sharp knife.

2. Rinse the area again and apply topical steroid ointment .

3. Aromatic spirits such as ammonia to the affected area may cause relief of the symptoms .

Mild cases respond well to oral antihistamines .

Severe cases may need intramuscular injection of ACTH or corticosteroid injections such as (Solu-medrol) and intravenous antihistamine .

These medications usually cause immediate and dramatic relief .

Erythematous wheals may appear few hours after bathing in the ocean. The most common site involved is the area covered by the bathing

 suite.

In children, the lesions appear mainly on the buttocks and about the waist on the pressure areas of the bathing suite. The rash may be due to Schistosoma, jellyfishes or other organisms .

Topical corticosteroid ointment .

Antihistamine orally may be effective to relieve itching .

Systemic steroids are rarely required .

The effects of snakebite vary according to the composition of the venom.

The severity of the reaction depends mainly on the type of toxin carried by different snake venom.

The bites of the spitting cobra produce local swelling, necrosis, hematological abnormalities and complement depletion .

Other species contain a neuro-toxin that interferes with transmission at the neuromuscular junction besides marked coagulation disturbances.

The first aid and field management of victims of snakebites has changed since 1979 when the compression bandage-splinting method of first-aid treatment was introduced and proved to be effective.

This consists of the application of a firm compression bandage to the limb that has sustained the bite, and it is immobilized by splinting .

If it is not possible to apply this method and for time saving, an immediate tourniquet from any available cloth or string can be used. This legation should not be too tight or too loose, just to obstruct venous and lymphatic flow and not the arterial blood.

Specific antivenom vaccine if the type of snake is identified or polyvalent vaccine is available.

Sucking of the site of the bites is used by some natives on condition that there is no any trauma or abraded area of the lips and the mouth. Sucking devices are available and can be used if there is an indication for that especially to detect the type of venom.

Anti-shock measures .

Treatment of secondary infection and lacerated skin .

An enzyme immunoassay method on urine ca be used.

Swabs taken from the bite site, or serum, may allow the venom to be identified within 30 minutes .

Scorpions are widely distributed in the tropics and subtropics. Their poisonous stings are responsible for considerable morbidity and mortality rates especially in infants and young children.

The venom is carried in the curved sting at the tip of the tail, which is swung over the scorpion‘s head to strike its victim. The principal component of the venom is a neuro-toxin agent with adrenergic and cholinergic effects, but some venoms also contain 5-hydroxytryptamine.

Fig. 152. Scorpion

Many scorpions are quite harmless, and their stings are of little effect .

The effects of scorpion stings may be local or systemic.

This is usually immediate, manifesting with severe burning pain, numbness of the affected limb and marked swelling.

Systemic manifestations include the following: restlessness, profuse sweating. muscle spasms, difficulty with speech, marked increase in salivary and lachrymal secretion, tachycardia, bradycardia and arrhythmia.

Tightness sensations develop in the throat.

Death is usually due to respiratory or cardiac failure.

1. Proximal tourniquet should be applied immediately to the affected site , releasing of the tourniquet every 10 minuets .

2. Ice packs should be applied for two hours to the site of the sting .

3. Local anesthetic injection around the sting site helps to relieve pain.

4. Specific antivenom by intravenous injection is the treatment of choice.

5. Atropine to counter the cholinergic effects of the venom.

6. Adrenergic blocking agents to antagonize the effects on the cardiovascular system .

7. Barbiturates to counter the neuroexcitatory effects.

8. Corticosteroids may be needed.

N.B. : Demerol is contraindicated .

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