Infectious disease Caused by tiny organisms called pathogens (ex. Bacteria, viruses, fungi or protists) Can come from another person, contaminated object, animal bite, or environment The immune system is responsible for distinguishing the difference between the different kinds of pathogens and reacting accordingly Once a pathogen enters the body, it works by damaging individual cells in the organs or attacks entire systems

Colds Illness caused by a viral infection in the respiratory system Once inside the body, the virus multiplies and attacks mucus membranes of nose and throat causes the common effects of the cold (sore throat, runny nose, fever) Since its caused by a virus, it cannot be treated with an antibiotic

Influenza (flu) Highly contagious viral infection of respiratory system Typically causes fever, muscle aches, and a more severe cough than common cold Usually lasts longer than a cold

Athlete’s foot Common fungal infection of the skin of the feet Fungus may be contracted from public environments Grows in the warm and moist environment usually between toes Can be difficult to cure

AIDS Acquired immunodeficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV) The virus attacks the cells in the immune system, making the organism unable to fight off other pathogens that can attack the body

Strep throat Contagious disease caused by bacterial infection Symptoms include fever, pain, redness and swelling of the throat and tonsils May produce mild or severe symptoms