Generally spiders do not cause any harm to the human beings,even spider bite do not cause rupture of skin.There are about 30000 species of the spiders are known out of which only few are known to us.Spiders such as black widow spiders and brown recluse are poisonous.Tarantulas bites are painful. Black widow spider is a medium sized spider.The name so called as the female black widow spider kills her male counterpart just after the mating.Black widow spider generally found in the southern united states.This is generally found in darker areas as it is a nocturnal animal and hence it is active during the night.They are not present in human houses but in unused areas they can be present.Five species of a black widow spider is known out which only two can cause harm:Southern black widow and northern black widow.The two can be esaily differntiated on the basis that SBW has black and shiny abdomen while the NBW has red spots  on the abdomen.She bites humans when her eggs are being disturbed by someone owing to the protection of eggs.

The bite of a black widow spider causes this condition.

Prevention from the bite of black widow spider is to avoid accessing to the areas where the fear of biting form it is more like indark areas,etc
 

After biting, when a patient is taken into ahospital then it should be confirmed that there is availability of antivenin in the hospital
 

Sensitization from the rattlesnake antivenin can occur if black widow spider antivenin is use to treat.So, physician should discuss life style habits that might affect the person's risk of incurring a snake bite in the future.