Almost all spiders produce poison. However, often the spider bite can not pierce man’s skin because most spiders have very fragile teeth, so they are harmless.
The spider bite can cause mild itching for a few hours, but sometimes it can be dangerous.
Some species that cause dangerous reactions in humans are:
- The Black Widow (Latrodectus) has a size ranging from 8 to 40 mm. The color is black but has a red hourglass-shaped blotch on the abdomen;
- The brown spider (also known as spider-violin or brown recluse) is 6 to 20 mm in size, red-brown and has a darker small spot on the abdomen in the shape of a violin.
These spiders can cause a serious reaction that needs to be treated with a skin graft or even amputation.
Brown Spider Sting
The brown spider is recognized by the tiny violin-shaped patch on its back.
This spider rests during the day and is not aggressive, but it attacks when it is provoked .
Generally, people are stung only if they wear clothes and shoes on which the spider is.
Most brown spider bites are asymptomatic.
Loxoscelism is a disorder caused by the brown spider.
Generally, the bite is painless , but then it becomes an injury:
- Painful (1)
Necrosis (cell death) spreads a few days after the bite and causes a necrotic dermatitis , the surrounding skin becomes color :
- Redness ( erythema ),
- White (Ischemia),
- Blue (necrosis).
The venom of this spider contains enzymes hyaluronidase and sphingomyelinase D and causes necrosis.
In addition, the activity of neutrophil white blood cells and platelets increases necrosis.
Among the symptoms in the bite area are:
In addition, it may cause systemic symptoms, including:
In some cases, clotting problems can cause a stroke .
Hobo Spider Sting
The Hobo spider is brown with gray markings on the body.
His behavior is aggressive even after slight provocation.
The symptoms caused by their sting are similar to those of the spider but, more:
- Necrosis is rare,
- Generally, a permanent scar remains in the area of the bite (3).
The causes of necrosis can be:
- The hemolytic properties (destroys the red blood cells) of the venom,
- The transmission of bacteria within the bite area.
The systemic symptoms of the bite may be:
- Headaches ,
- Anaphylaxis or anaphylactic shock (severe allergic reaction),
The treatment is similar to that of the brown spider.
In addition, tissue tissue resection should not be performed prior to the completion of the necrosis process, ie when the lesion stops growing.
Black Widow’s Sting
The black widow has a black hairless body.
Males are smaller than females.
The main feature of its appearance is a red spot on the abdomen, similar to an hourglass.
It is not aggressive under normal circumstances, it only attacks if provoked, especially to protect the eggs.
In addition, it is the most important poison spider:
- In North America,
- In Australia.
Its venom is alpha-latrotoxin (neurotoxic) that stimulates and causes the release of neurotransmitters at the level of parasympathetic neurons that release:
- The catecholamines,
The symptoms caused by the bite of this spider are called latrodectismo. The pain caused by your sting is like a pinch.
An injury surrounded by several red rings (resembling an ox eye) can be seen in the area of the bite.
Latrodectism begins in a few minutes with the development of pain throughout the body and in a few hours appear symptoms such as:
- Vomiting ,
- Respiratory insufficiency,
- Partial paralysis of the limbs,
- Abdominal cramps ,
- Arterial hypertension
- Fever ,
- Fasciculation (muscular contractions that do not produce movement),
- Muscle spasms.
Symptoms may be confused with an acute abdomen ( very severe belly pain ).
Generally, and black widow stings during the hot months. Rarely does a visible signal remain on the skin , but in 25% of cases it occurs:
- Sweating ,
- Erection of hair.
The diagnosis is based on the patient’s medical history.
Rarely the sting is lethal, the mortality after sting is less than 1%.
Picado de Tarântula
The tarantula has a brown or black furry body.
The size can reach 7-8 cm.
This type of spider also represents a pet.
Its venom is not dangerous to humans and only creates lesions without symptoms, except fever .
The tarantula defends itself with stinging hairs on its body (2).
If these hairs penetrate the eyes, they can cause inflammation.
In the case of uveitis , your doctor may advise:
- Eye wash,
- The application of topical corticosteroids .
Bite of Phoneutria nigriventer (banana spider)
These spiders have long legs.
Since they often hide in banana boxes, they are known as banana spiders.
The bite symptom is a severe pain (in 96% of patients).
The sting of this spider can cause respiratory failure and death:
- In newborns,
- In children,
- In the elderly.
Its venom is neurotoxic and stimulates the autonomic nervous system causing:
- tachycardia ,
- High pressure ,
- Excessive salivation ,
- Priapism (painful erection),
- Dizziness ,
- Visual disturbances.
There is an antivenom for the treatment of these patients, but it is rarely used.
Symptoms of spider bite
The most common spider bite symptoms are:
Signs of worsening of the sting or spread of the venom are:
- The blisters on the surrounding skin,
- Sensation of numbness and tingling .
Some symptoms of spider bite can spread to other parts of the body.
If you experience the following symptoms, you should see your doctor:
- Leg cramps
- Stomach cramps
- Excessive sweating
- Generalized muscle and joint pain
- Fast heart rate.
The weakness can be one of the symptoms of spider bite, so it is essential to make a cure.
The spider type can not be identified by the type of venom injected, except in some cases.
Bite Symptoms of the Brown Spider
The brown spider is among the most dangerous and can be recognized by the venom.
Initially, the sting of this spider does not cause pain, but after about one hour symptoms occur in the bite area, including:
- Intense pain,
- Itching can also be generalized,
- A bubble surrounded by reddish skin,
- Ulcer, the bubble stretches, breaks and forms an ulcer on the skin.
The brown spider bite causes so much localized discomfort, systemic symptoms rarely occur, such as:
Black Widow Bite Symptoms
The black widow causes severe symptoms that include:
- Numbness in the affected area,
- Muscle cramps and stiffness (thorax, abdomen and shoulders)
- Severe respiratory distress.
In severe cases, an antidote is needed, otherwise it continues to spread.
What to do? Treatment for spider bite
You should see your doctor if the symptoms:
- They begin to reach a wider area,
- Persist for more than 24 hours.
If the person has not had the anti-tetanus vaccination recently, contact a doctor immediately.
It is difficult to predict the severity of the spider bite because you can not easily recognize the type of arachnid you stung.
First aid for spider bite are:
- Clean the wound,
- Apply ice .
If the spider bites one end (legs or arms), it is advisable to keep the limb raised.
Treatment for brown spider
All bites should be cleaned.
Patients who develop systemic symptoms need hospitalization.
The antivenom reduces the size of the necrotic area.
Before the antiveneno is administered, less the manifestations.
Studies show that it is useful when administered the first 4 hours after the bite, but according to one study, is also useful after 12 hours (5).
The sting-induced necrosis spreads in a few days and expands within a few weeks.
Surgical excision of cutaneous lesions is indicated only for stabilized (non-expanding) lesions.
Cortisone is indicated:
- For bites that cause severe skin lesions,
- For loxoscelismo,
- In young children.
The antibiotic Dapsone should only be used in adult patients with necrosis who also have glucose-6-phosphate dehydrogenase deficiency.
Topical nitroglycerin may be useful in blocking the expansion of necrotic ulcers.