What is Harmful Microorganisms?

Microorganisms cause many diseases in humans, animals and even plants. They can enter the body of the host organism through different modes such as air, water, food, insect’s cuts and wounds and direct contact. All these modes are called modes of disease transmission. The microorganisms that cause diseases are called pathogens or germs.
The diseases that can spread from one person to another are called communicable diseases. Cold and cough, tuberculosis, cholera and malaria are some examples of the communicable diseases that get transmitted through different modes of transmission.
 

Diseases in Human Beings:
Through Air:-  

Could and cough and tuberculosis are the examples fo some diseases that can get transmitted from an infected to a healthy person through air. The pathogens of these diseases enter the air when the infected person coughs or sneezes. The healthy person who breathes the infected air also suffers from the disease.

Through insects:-  

The diseases that are transmitted through insects such as flies and mosquitoes are called vector borne diseases. Flies sit on dirty and unhealthy places like garbage or drains and carry germs attached to their bodies. They transfer these germs to the food items they sit on. On consumption of infected food and water a healthy person gets infected with the disease. Typhoid and cholera some examples of the diseases caused by consumption of infected food and water. Similarly, mosquitoes bite an infected person and transfer the disease to a healthy person though bite. Malaria and dengue are transmitted through mosquito bites.

Through cuts and wonder:-  

Tetanus is a disease caused by the bacterium, Clostridium tetanus. The bacteria enters the body through a break in the skin such as cut or wound.