Communicable (infectious) diseases spread from person to person through pathogens. Cholera (bacterial Vibrio cholerae through water), Common cold (viral through air/droplets), and Chickenpox (varicella-zoster virus through air/droplets) are all communicable. Anemia is a non-communicable condition - it is a deficiency disease caused by lack of red blood cells or hemoglobin (from iron deficiency, vitamin B12 deficiency, blood loss, or genetic conditions like thalassemia), not by infectious agents.