Diseases and their spread biology lesson for kids: 1st, 2nd, 3rd, 4th, 5th, 6th and 7th grades biology lesson.
There are many kinds of diseases. Some are caused by organisms that make you sick. These disease-causing organisms are called pathogens, and the kinds of diseases they cause are called infectious diseases.
There of four types of pathogens. First, there are viruses, very small organisms that make you sick by hijacking your own cells’ DNA to make copies of itself. Viruses are so small and their structures are so simple that they don’t even count as cells. The common cold is caused by a virus.
Bacteria (singular: bacterium), on the other hand, are single-celled organisms that make you sick because they release toxins as they grow in your body. Tuberculosis is a bacterial infection.
There are other organisms called parasites that can make you sick. Fungi (singular: fungus) and other kinds of organisms use the body’s resources for themselves, which means less for us.
There are different ways that pathogens can be spread. The first is direct contact with an infected person. This can happen for diseases like the common cold, for example, if the sick person sneezes into their hand. If you touch their hand and put your hand to your mouth, you can get sick. Sometimes, animals carry diseases that can make you sick if they bite or scratch you.
For some diseases, you don’t need to come into direct contact with somebody to catch the pathogen. Some viruses like the cold virus can live for a while on any surface that the infected person touches. Also, some pathogens are airborne, which means they move through the air from person to person. The cold is like this, too.
Another way that you can catch a pathogen without direct contact with a person is through vectors, animals that carry the pathogen from one place to another without getting sick themselves. Malaria and dengue are passed on that way; the tiny parasites hop a ride on mosquitos when they bite you, they leave the pathogens behind.
Some pathogens can enter our bodies through the food we eat, too. E. coli, a bacterium, can be found in undercooked beef or in unpasteurized milk. Then, when you eat it, it makes you sick.
Every disease, including infectious diseases, have different symptoms. Some of them make you cough or sneeze, some give you fevers, some make you vomit or give you diarrhea, others cause pain. Sometimes, the body will fight off these infections by itself and these symptoms will go away, but sometimes you need to go to the doctor to give you medicine and help you get better.
If you have a rash or swelling, have been coughing for more than a week, find it harder to breathe, have a headache with fever, or fever for a long time, it is important to go to the doctor to have them check you out.