Infections are caused    by either bacteria or viruses . Viruses are very tiny germs made of genetic material inside of a protein coating. Viruses cause infection diseases such as common cold ,flue and warts. VirusES can kill , damage, or change the cells and make people sick . Different viruses attack different part of the body and certain cells such as blood , liver and lungs. In some cases the immune system of body fights against viruses so people do not feel sick but in other cases immune systems are not able to get rid of viruses and then infection's symptoms appear .   Flu could cause infection  and its  symptoms can be 1 or 2 or all of  the list bellow                                                         
  .Fever                                                                                                                                                              .Chills and sweats.
.Change in cough or a new cough.
.Sore throat or new mouth sore.
.Shortness of breath.
.Nasal congestion.
.Stiff neck.
.Burning or pain with urination.
.Unusual vaginal discharge or irritation..Increased urination.
.Redness, soreness, or swelling in any area, including surgical wounds and ports.
.Diarrhea.
.Vomiting.
.Pain in the abdomen or rectum.
.New onset of pain