Infectious diseases are caused by harmful organisms such as bacteria, viruses, fungi, or parasites. While many of these organisms coexist harmlessly in our bodies, some can cause illness under specific conditions. Infectious diseases can spread through person-to-person contact, insects, animals, contaminated food, water, or environmental exposure. Symptoms may include fever, fatigue, coughing, muscle aches, and diarrhea.

Prevention methods include vaccines for diseases like measles and chickenpox, and frequent hand-washing. Seek medical attention if you experience severe symptoms like breathing difficulty, persistent cough, severe headaches with fever, or unexplained rash or vision problems.