Latrodectism

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Latrodectism is the clinical syndrome caused by a neurotoxic venom that can be injected by the bite of any spider that is a member of the spider genus Latrodectus, in the family Theridiidae.

The most well known of member of the Latrodectus genus is the Black Widow Spider (L. mactans).

1 Venom method
2 Symptoms
3 Treatment
4 Risk indications for complications
5 Mortality rate
6 External links

[edit] Venom method

The venom spreads rapidly throughout the body and acts by causing the release of the neurotransmitter acetylcholine, which is involved in muscular contraction.

If enough venom is injected into a person's body, initially a severe pain in local muscle groups occurs, and the pain then spreads to regional muscle groups.

The spread relates to the toxin initially being carried by the lymphatic system until it reaches the blood stream. Once in the blood, the venom is moved by circulation, causing its toxins to be deposited in nerve ends where nerves insert into muscle.

The venom acts at nerve endings to prevent relaxation of muscles, causing tetany — constant, strong, painful muscle contractions. Thus initial pain is often followed by severe muscle cramps.

Contraction of musculature may extend throughout the body, though cramping in the abdomen is frequently the most severe. Back and leg muscles can often be affected too.

[edit] Symptoms

Symptoms occur in three main phases: exacerbation phase, dissipation phase and residual phase.

[edit] Exacerbation phase

During the first 24 hours after a bite:

Severe pain in muscle groups local to the bite.
Muscle cramping, primarily in the abdomen, back and thighs.
Headache, dizziness, tremors, salivation, diaphoresis (excessive sweating), nausea and vomiting.
Anxiety, fatigue, insomnia.
Lacrimation (tearing of the eyes).
Migratory arthralgia (joint pain).
Tachycardia (rapid heart beat), bradycardia (very slow heart beat), restlessness, hypertension (elevated blood pressure), Tachypnea (hyperventilation).

In some rare and extreme cases, severe complications can arise:

Acute renal failure (failing of kidney function).
Myocarditis, rhabdomyolysis, paralysis.
Shock, coma, and death.

Symptoms that may be present at or near the wound:

Rash, slight erythema (redness of skin), Piloerection (goose bumps).
Mild edema (swelling due to excess fluid).
Lesion or mild infection (rare).

[edit] Dissipation phase

During the first 1 to 3 days after the bite:

Symptoms start to decline.

[edit] Residual phase

During the following weeks or months:

Muscle spasm, tingling, nervousness and weakness.

[edit] Treatment

People who have been bitten by a poisonous spider should always seek out professional medical assistance immediately. Though complications are rare, and death is even rarer, when things go wrong, it can happen quite quickly. Any changes in heartbeat, breathing or blood pressure should be considered especially ominous.

Standard treatments usually involve symptomatic therapy with pain medication, muscle relaxants, and, rarely, antivenom. The venom does not typically cause problems at the bite site itself, unless a secondary skin infection occurs.

Antivenom is generally reserved for use only when absolutely necessary. Due to the low mortality rate of victims, the risk of major injuries or death due to serum sickness are greater than the risk of death due to the venom itself. In past years, injections of calcium gluconate were used to replace calcium rendered unusable by the neurotoxins, but hospitals have been switching over to the use of prescription painkillers — especially opiates such as morphine — to reduce symptoms, as the calcium injections do very little for the pain and do not significantly reduce the recovery time.

[edit] Risk indications for complications

In general, bite victims who are very young, old, hypotensive, pregnant, or who have existing heart problems are the most likely to suffer complications with latrodectism.