Ayurveda, the science of life, is the most ancient medical doctrine of human civilization. This has evolved gradually from its classical treatise based knowledge to the present-day textbooks and from Gurukul education to a college-based education system. The classical Ayurveda texts do not make a clearer distinction across the disciplines except for a few. Though some of the proponents have been credited with expertise of some of the branches, all of them have described various theories, concepts, and principles across many disciplines. For instance, Acharya Sushrut is called as the father of Indian surgery, but his classical doctrine Sushruta Samhita also describes other branches of Ayurveda, such as medicine and pathology, and is the same with Acharya Charak, who is credited as the father of Indian medicine.


However, certain basic principles described in Ayurveda have remained intact and are still the same as today’s medical science. This could be equally applicable to the realm of epidemiology which is a branch of medicine that deals with “the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to control of health problems. Populations, as with individuals, have unique patterns of disease. Populations’ disease patterns derive from differences in the type of individuals they comprise, in the mode of interaction of individuals, and in the environment in which the population lives. The science of epidemiology, which straddles biology, clinical medicine, social sciences, and ecology, seeks to describe, understand, and utilize these patterns to improve health.

The Niyata Hetu are a category of inevitable factors that affect commonly to all the individuals in a particular community and include the harmful effects of sun, moon, stars, and planets such as floods, cyclones, landslides, earthquakes, and tsunami. Aniyata Hetu is the evitable disastrous factors that include Prajnaparadha (terrorism, accidents, etc.), Shastra prabhavaja (wars–nuclear weapons, missiles, etc., advanced weapons), Abhisyangaja (effects of pathogens, evil forces and unhygienic condition), and Abhishapaja (curse). Besides affecting the individuals, these factors also affect the entire community resulting in widespread disease causation known as Janapadodhwansa Rogas.A physician’s job is to know the human body and its functions in terms of Prakritisthata (homeostasis). The four cornerstones of diagnostic medicine, each essential for understanding homeostasis, are: anatomy (the structure of the human body), physiology (functions of Dosha, Dhatu and Mala), pathology (what can go wrong with the anatomy and physiology) and psychology (thought and behavior)

Etiology is a branch of medical science that deals with the cause and origin of disease. Akin to modern medicine the classical treatises of Ayurveda also describe the cause and origin of disease. This part of the paragraph primarily describes the cause of communicable disease and epidemic as described in Ayurveda. Chakrapani, one of the critics of Charak, describes the causation of disease and epidemic. He says that although individuals defer in physical constitution, food habits, suitability, strength, immunity, age, etc., they do get affected with disease owing to vitiation of some factors that are common to all those who inhabit in that community. These factors lead to the simultaneous manifestation of disease having the same set of symptoms among all the inhabitants leading to widespread manifestation in the community. The factors that are common to all the individuals in a community include air, water, land, and season. Again, Acharya Charaka has divided the etiological factors into two different categories, such as Niyata Hetu and Aniyata Hetu.

Once the doctor knows what is normal and can measure the patient’s current condition against those norms; she or he can then determine the patient’s particular deviation from homeostasis and the degree of deviation. This is called diagnosis. Once a diagnosis has been reached, the doctor is able to propose a management plan, which will include treatment as well as plans for follow-up. From this point on, in addition to treating the patient’s condition, the doctor educates the patient about the causes, progression, outcomes, and possible treatments of his ailments, as well as providing advice for maintaining health. In the beginning, most of the students and practitioners find that it is very difficult to diagnose a disease on the basis of Ayurvedic principles or if they manage to diagnose, they still may not feel satisfied. I think we have failed to teach and train the students to perform Ayurvedic diagnosis. It is so simple, clear and easy to do Ayurvedic diagnosis, provided that the students have qualities such as intuition, knowledge, examination skill, logical thinking and continuous practice. It is essential to get the direct training from the Guru in order to become perfect in Ayurvedic diagnosis, as evidenced from the Vagbhata’s citation. The proficiency comes by continuous practice, just like the genuineness of diamond etc. cannot be known by mere reading of books. Aptopadesha, Pratyaksha and Anumana Pramana are the methods used for the understanding the stage, state and site of Dosha; state of Dooshya and the site of Dosha-Dooshya Sammurchana. Ayurveda advises to examine the person as a whole, treat as a whole and use the drug as a whole.

In order to diagnose the disease on the basis of Ayurvedic principles, the physician should work very hard to know the subtle changes occurring inside the body due to the imbalance of Dosha. To become perfect in Ayurvedic diagnosis, the physician needs to understand Dosha Vikalpa (Dravyataha-Gunataha-Karmataha Vriddhi of Dosha), Dhatu Vaishamya (the quantum of vitiation, the status of Dhatu and Srotas), Agni Sthiti (condition of the digestive fire viz. Samagni, Mandagni etc.) and status of Ama (Intermediate matter) in body.