Mohammed Asrar

Communicable diseases are caused by very tiny organisms called germs and parasites. These germs are present everywhere- in air, water, soil, etc. When germs enter a healthy body, they multiply and upset the normal functioning of the body.The gap between the entry of germs into our body and the appearance of symptoms is called the incubation period.During incubation, a person may look healthy but still carry the germs.They can spread the disease to others.