Disease classification based on occurrence:
1)Endemic disease: When a disease is a more or less constantly present form year to year in moderate to a severe form in a particular part of the country or state it is classified as endemic to that area. Example- Early blight of potato.
2)Epidemic disease: A disease that occurs widely and periodically. Occasionally it attains the severe form. Example- Redrot of sugar cane, Late blight of potato, wheat rusts.
3)Sporadic disease: Occur at very irregular intervals and locations. Ex- Green ear disease of Bajra.
4)Pandemic disease: When a disease prevalent throughout the country, continent or the world is known as a pandemic.