• There are 6000 species of spiders in Africa, of which a few are venomous.spider image by wilmar huisman from Fotolia.com
  
  Africa is home to as many as 6000 of the named 35,000 species of spider in the world. While most spiders are not harmful to humans, a traveler to Africa should be wary of four groups of spiders that are: the button spiders, the violin spiders, the six-eyed sand spiders and the long-legged sac spiders. These spiders produce a toxic venom that can be lethal. The effect of a spider bite depends on the age and sensitivity of the person bitten, the site of the bite, the quantity of venom that enters the body and the species of the spider. Since treatment depends on the species of spider, identification is very important.
  
  

Button Spiders

• There are four species of black button spiders and two species of brown button spiders found in Africa. They are usually found in natural habitats and very rarely, if ever, in built-up areas. These spiders have round abdomens marked with spots or stripes and slender legs, of which the third pair of legs is the shortest. The male is considerably smaller than the female, and only the female has the capacity to pierce the skin of humans.
  
  The black button spider is pitch black in color. The male has red and white bands of color on its abdomen while the underside of the female abdomen could either have no color or have one distinct hourglass pattern. The female spider is also called the widow spider because she kills the male after mating with him.
  
  The black button spiders are more venomous than the brown button spiders.
  The brown button species are cream, gray, brown or black in color. The underside of the abdomen has red to orange hourglass markings, and the upper side of the abdomen often has a geometrical pattern. This is especially common in the paler species.
  
  The symptoms of a black button spider bite include sweating, increase in blood pressure, restlessness and palpitations, nausea, pain and cramps with stiffness of the stomach muscles and weakness in the legs. The patient must be hospitalized and an anti-venom should be administered.
  
  The symptoms of a brown spider bite include a burning sensation and pain restricted to the site of the bite. Often there is a localized rash that clears up in a couple of days.
  
  

Violin Spiders

• Violin spiders live in caves and under rocks and wood logs. Their color ranges from brown to reddish brown. They are about 8 mm long with long slender legs around 18 mm long. The abdomen is either plain or has light and dark markings. Often, a violin-shaped marking is noticeable. These spiders have three pairs of eyes that are very closely spaced.
  
  The bite of a violin spider becomes painful only after a few hours of the bite. The region turns red and swells. If it turns purplish, it indicates local tissue death. A tetanus injection is administered. Sometimes skin grafts are required. Healing could take weeks or months depending on the severity of the bite.
  
  

Six-Eyed Sand Spiders

• These spiders are found in sand, on sand dunes, under rocks and on rock overhangs. They are usually found covered in sand and this makes them difficult to spot. They have a flattened appearance and are 9 to 19 mm long with a leg span of 50 mm. The legs resemble those of a crab. They have three pairs of eyes that are widely spaced.
  
  There have been no definitive cases of sand spider bites recorded, and there is no anti-venom treatment available either. However, toxicology reports suggest that the venom of sand spiders is very potent; experiments on rabbits have proved lethal.
  
  

Long-Legged Sac Spiders

• These spiders are pale yellow to yellowish green in color. They have two pairs of legs directed forward and another two directed backward. Of these, the first pair of legs is the longest. The tips of the legs and the mouth are darker than the rest of the body.
  
  The symptoms of a sac spider bite include fever and a red, swollen and itchy rash. A tetanus injection is required and sometimes antibiotics are needed, too.