But not all bacteria are bad. Some bacteria are good for our bodies - they help keep things in balance. Bacteria are also often used as tiny factories to produce medicines and vaccines that are genetically engineered. Viruses can't live outside of other living cells. But once they are inside the body, viruses can spread and make people sick.
Viruses cause chicken pox , measles, flu , and many other diseases.
Unlike other plants, fungi aren't able to produce their own food from soil, water, and air. Instead, fungi get their nutrition from plants, food, and animals. Fungi thrive in damp, warm environments. Most fungi are not dangerous. An example of something caused by fungi is athlete's foot - that itchy rash that teens and adults sometimes get between their toes.