Discover how a disease can spread from person to person. Life processes - Humans and other animals - Reducing the spread of disease Learning Points Microorganisms such as viruses and bacteria spread disease. The immune system sends white blood cells to attack viruses and bacteria. A Twig Curriculum Film. Delivering key learning points. Get straight to the facts in just three minutes – directly linked to core learning, Twig's curriculum films will fit neatly into your lesson plans.