Infectious diseases

Infectious diseases are disorders caused by organisms — such as bacteria, viruses, fungi or parasites. Many organisms live in and on our bodies. They're normally harmless or even helpful, but under certain conditions, some organisms may cause disease.

Some infectious diseases can be passed from person to person. Some are transmitted by bites from insects or animals. And others are acquired by ingesting contaminated food or water or being exposed to organisms in the environment.

Signs and symptoms vary depending on the organism causing the infection, but often include fever and fatigue. Mild complaints may respond to rest and home remedies, while some life-threatening infections may require hospitalization.

Many infectious diseases, such as measles and chickenpox, can be prevented by vaccines. Frequent and thorough hand-washing also helps protect you from infectious diseases.

Symptoms Causes Risk factors Complications Prevention

Each infectious disease has its own specific signs and symptoms. General signs and symptoms common to a number of infectious diseases include:

  • Fever
  • Diarrhea
  • Fatigue
  • Muscle aches

When to see a doctor

Seek medical attention if you:

  • Have been bitten by an animal
  • Are having trouble breathing
  • Have been coughing for more than a week
  • Have severe headache with fever
  • Experience a rash or swelling
  • Have unexplained fever
  • Have sudden vision problems

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