The microbes that cause disease and how they spread. How an infection affects the body, the principles of treatment and of prevention, and how vaccines and a healthy community keep disease away.
3 lessons, about 1 h 30 min3 simulations10 problems3 practice questionsPython in every lesson
Infectious diseases are caused by microbes: viruses, bacteria, fungi, protozoa and worms. They spread through the air, through water and food, through contact and blood, from mother to child, and by carriers called vectors, such as the mosquito. Where a microbe settles in the body decides which signs appear.
Treatment can ease the signs, or it can kill the microbe that causes them. Antibiotics kill bacteria by blocking steps that bacteria need and human cells do not. They do not work on viruses. Prevention is better than cure: keep the microbes away, or make the body ready with a vaccine.
The immune system recognises and kills microbes. A vaccine gives it practice with a harmless form of the microbe, so that it acts quickly later. Edward Jenner began vaccination with cowpox against smallpox. When many people are vaccinated, even the unprotected are safer. HIV is a case of a disease that attacks the immune system itself.
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