pathogens

Pathogens are living organisms (or tiny agents) that cause disease when they enter the body and multiply.

• Common types include bacteria, viruses, fungi, protozoa, and worms.
• They make us ill by damaging cells, producing toxins (poisons), or triggering strong immune reactions like fever and inflammation.
• Not every microbe is a pathogen: many microorganisms are harmless, and some are even helpful (for example, “good bacteria” in the gut help in digestion).
• How they spread depends on the pathogen: through air (cough/sneeze), contaminated food or water, direct contact, or via carriers like mosquitoes.
• A pathogen may cause disease only when it gets the right chance—like when immunity is weak or when it enters through a cut, the mouth, or the nose.

Knowing what pathogens are helps explain why hygiene, safe food and water, vaccination, and clean surroundings are so important for preventing communicable diseases.