Insect bites and stings are a common source of injury to the skin, particularly during warm weather when outdoor activities are popular. Insects bite because they require human or animal blood for food or to produce eggs. An insect may sting when it feels threatened and is trying to defend itself.  

Although generally referred to as insect bites or stings, many such injuries are caused by creatures other than insects, including various arachnids (e.g., spiders, ticks, mites). When the skin is bitten or stung, the insect or arachnid injects saliva or venom. In most cases the body’s immune system reacts mildly to the saliva or venom, typically resulting in a small, red and itchy bump that disappears within a few hours or days. However, some patients develop large sores (ulcers) with pain and swelling.

Most bites and stings do not require emergency medial treatment, although young children and the elderly may be more affected by bites and stings.

In some cases, bites and stings can result in a variety of complications, including:

• Dermatitis. An inflammation of the skin that can have many causes and occur in many forms. The term usually describes skin that is swollen, red and itchy and can be an allergic reaction. It is neither life threatening nor contagious.
  
  

  

• Other allergic reactions. A mild allergic reaction may result in nausea, swelling and other discomforts. In rare cases, an insect sting can result in a severe, potentially life-threatening allergic reaction known as anaphylactic shock. This can impair breathing and heart function, leading to death in some people.
  
  
• Infection. Some insect bites can cause bacterial infections, such as impetigo, a contagious superficial skin infection produced when bacteria commonly present on the skin enter through the bite opening. If not treated properly, cellulitis, a skin infection of the deeper layers of the skin characterized by redness, swelling and pain, may occur.
  
  
• Disease. Some insects carry bacteria or viruses. Some of the most common diseases caused by bites and stings include:
  
  
• • Lyme disease. An infectious disease spread by bacteria-carrying ticks. Symptoms can be as mild as a rash at the bite site, fever and chills and as serious as muscle paralysis, severe arthritis or heart and neurological disorders in the late stages of the disease.
    
    
  • West Nile virus. A disease primarily spread through the bite of an infected mosquito that affects the central nervous system in humans and animals. Mosquitoes become infected when they feed on infected birds. Most people infected with the virus experience no symptoms, although some may experience flu-like symptoms. Some severe cases have resulted in death.
    
    
  • Rocky Mountain spotted fever. A rare bacterial disease transmitted to humans through the bites of ticks. It is characterized by small pink spots on the wrists and ankles that spread to other parts of the body, become larger and bleed.
    
    
  • Malaria. An infectious parasitic disease transmitted by the bite of an infected female mosquito. It includes cycles of chills, fever and sweating. Malaria causes millions of deaths worldwide in tropical areas, although it is extremely rare in the United States.
    
    
  • Dengue fever. An infectious viral disease found in tropical climates that is transmitted by mosquitoes and characterized by rash, fever, sore throat and aching head and joints.
    
    
  • Encephalitis. An inflammation of the brain, often caused by a viral infection. Exposure occurs through insect bites, food or drink, or skin contact. Travelers are most at risk from insect bites.