Write short notes (1-2 sentences) on each of the following:

1. Disease

2. Pathogen

3. Allergy

1. Disease — Any physical or functional change in the body from a normal state which causes discomfort or disability is called a disease. Disease is a departure from normal health through structural or functional disorder of the body.

2. Pathogen — Micro-organisms which cause communicable diseases are called pathogens. These germs are transmitted through various agencies like air, insect bites, rodent, contaminated food or water, etc. Pathogens may be different kinds of bacteria, viruses, fungi, protozoa or worms.

3. Allergy — Allergy is an unpredictable reaction of the body to a particular substance called allergen. A few common allergens are dust, spores, pollens, certain clothes, particular medicines, cosmetics, etc. Asthma, Eczema, Diarrhoea, Vomiting, Nausea, etc. are some of the common allergic reactions.