Theory:

Communicable and non-communicable diseases:
The manifestations of diseases are different depending upon several factors. In general, diseases are broadly classified into two types. They are communicable and non-communicable diseases.
  
1.  Communicable diseases:
The diseases which are passed on from one person to other through various routes such as air, water, food, physical contact etc., are known as communicable diseases.
They are also known as infectious diseases.
Example:
HIV, hepatitis A, B and C, measles, salmonella, influenza, ebola, coronavirus, tuberculosis, mumps etc.,
2.  Non-communicable diseases:
The diseases which cannot spread from person to person are known as non-communicable or infectious diseases.
They are also known as non-infectious diseases. These diseases remain confined to the diseased person and do not infect others. Most of these diseases are caused by nutrition deficiencies.
Example:
Diabetes, cancer, heart diseases, obesity, arthritis, haemophilia, marasmus, kwashiorkor, osteoporosis, osteoarthritis etc.,
Acute and chronic diseases:
Based on the duration of infection, diseases are classified into two types. They are as follows:
 
1. Acute diseases:
The diseases that last for only short periods and are severe are known as acute diseases.
These diseases do not cause long-term harmful effects on human health, and patients recover completely after the cure.
Example:
Cold, cough, cholera, typhoid, asthma, dysentery, bronchitis, sore throat etc.
2. Chronic diseases:
The diseases that last for a longer of time are known as chronic diseases.
These diseases are caused in the course of time and have long term effects on people's health.
Example:
Tuberculosis, arthritis, diabetes, cardiovascular diseases, elephantiasis, cancer etc.