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| REVIEW ARTICLE |
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| Year : 2016 | Volume
: 9
| Issue : 1 | Page : 20-26 |
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Fundamental tenets of epidemiology in Ayurveda and their contemporary relevance
Janmejaya Samal
Independent Public Health Researcher, Bhubaneswar, Odisha, India
| Date of Web Publication | 8-Jun-2016 |
Correspondence Address:
Dr. Janmejaya Samal
C/O-Mr. Bijaya Ketan Samal, At-Pansapalli, Po-Bangarada, Via-Gangapur, Ganjam 761-123, Odisha
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/2349-5006.183694
Background: Ayurveda, the science of life, is the most ancient medical doctrine of human civilization. Some of the basic principles described in Ayurveda are still the same as today's medical science. Ayurveda does not have a specific text as epidemiology, but the principles described in piecemeal can be compiled, analyzed, and interpreted in the light of modern theories of epidemiology.
Objective: An initial systematic literature review by the help of internet-based search engines revealed very negligible work in the field of Ayurveda and epidemiology. Hence, an attempt was made to analyze various principles of Ayurveda relevant to epidemiology and interpret their contemporary significance.
Methodology: The work is mainly based on theoretical research using standard textbooks of epidemiology and classical treatises of Ayurveda.
Discussion: A good number of principles are found in the classical texts of Ayurveda, which can be compared with the concepts of epidemiology. In the process of theoretical analysis, the following concepts were found relevant, such as the concept of causation of disease/Etiology of disease, causes of epidemic, classification of disease, modes of communicable disease transmission, and natural history of disease. In this study, attempt has been made to understand these concepts in the light of epidemiology with their most approximate delineation. However, being a classical medical doctrine, it has its own appeal that cannot exactly be compared with the concepts of epidemiology.
Conclusion: It is interesting to note that the tenets described centuries back are very much relevant at this present era, and their importance cannot be neglected. Keywords: Causes of epidemic, classification of disease, etiology, international classification of disease and natural history of disease
How to cite this article:
Samal J. Fundamental tenets of epidemiology in Ayurveda and their contemporary relevance. Indian J Health Sci Biomed Res 2016;9:20-6 |
| Introduction | |  |
Ayurveda, the science of life, is the most ancient medical doctrine of human civilization.[1] This has evolved gradually from its classical treatise based knowledge to the present day text books and from Gurukul education to college based education system.[2] The classical Ayurveda texts do not make a clearer distinction across the disciplines except 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 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.”[3] 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.[4] However, it would be overambitious to expect such concepts of epidemiology from the treatises of Ayurveda as the concepts are limited and very few are comparable. This paper attempts to unravel few concepts of epidemiology described elsewhere in classical treatises of Ayurveda. As said earlier, Ayurveda, the ancient medical doctrine, does not really have minute specialized tributaries as compared with the modern medicine, but many concepts described in those days are comparable with the concepts of modern medicine and holds equal importance. There are many concepts described in modern epidemiology which can not necessarily be compared with the concepts of Ayurveda, but few concepts those are found relevant to the present era are described in this study.
| Objective | | |
An initial attempt was made to review certain scholarly articles pertaining to the above-said subject by using systematic internet-based search engines. Keywords such as “concept of epidemiology, causation of disease, infectious diseases, communicable disease, epidemic and its management in Ayurveda” were used to obtain some pertinent scholarly work. PubMed, Google Scholar, and Google search engines were used for the purpose of literature search. The results obtained were not encouraging and very scanty in number. The idea of such a theoretical research stemmed out with this literature review, and the specific objectives of this review were to:
- Critically appraise the concepts of epidemiology in Ayurveda and
- Interpret their contemporary significance.
| Methodology | | |
The present work is primarily based on theoretical research. Standard textbooks of epidemiology and classical treatises of Ayurveda were used for the study. The classical texts of Ayurveda do not use such modern terminology; hence, approximate equivalent terms were obtained from Central Council of Indian Medicine, India.
| Discussion | | |
Etiology of diseases
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. 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.[5] Now, let us understand the concept of causation of disease in modern epidemiology and relate it to the concept of Ayurveda. In modern epidemiology, the concept of disease causation is understood by “Epidemiological Triad.” The following [Figure 1] explains the epidemiological triad.
Agent
The term agent is primarily referred to an infectious microorganism such as virus, bacteria, fungi, parasite, or other microbes. The presence of these organisms is mandatory for the disease to occur. However, they are necessary but not always sufficient to cause a disease. Physical and chemical factors are responsible for the causation of noninfectious diseases, hence are termed as agents in noncommunicable disease epidemiology.[6]
Host factors
Host factors are intrinsic factors that are peculiar to a particular host. These factors influence an individual's exposure, susceptibility, or response to a causative agent. Factors such as age, race, sex, socioeconomic status, and behaviors (smoking, drug abuse, lifestyle, sexual practices, contraception, eating habits, etc.,) are some of the many host factors that affect a person's likelihood of exposure. Furthermore, age, genetic composition, nutritional and immunologic statuses, physical structure, presence of disease or medications, and psychological makeup are some of the host factors that affect a person's susceptibility and response to an agent.[6]
Environmental factors
Unlike the host factors, the environmental factors are extrinsic factors which affect the agent and the opportunity for exposure. Usually, these factors include physical factors such as geology, climate and physical surroundings (including a nursing home or hospital); biologic factors such as arthropods that transmit the agent; and socioeconomic factors such as income, crowding, sanitation, and the availability of health services.[6]
Agent, host, and environmental factors interrelate in a variety of complex ways to produce disease in humans. Their balance and interactions are different for different diseases.[7]
Ayurvedic classical treatises have also described similar concepts as depicted in the above paragraph where Acharya Charaka and his critic has described all the three components. Both of them have reported about the agent and the environment together in the form of Niyata hetu and Aniyata hetu affecting individuals and thereby affecting the entire community causing widespread manifestation of disease. Again, it seemed that Acharya Charaka has emphasized on the environmental component and incorporated the agent factor in that. In addition, Acharya Sushrut has also depicted about the concept of microorganism that causes disease in humans. This is invariably the most accepted theory of disease causation. In epidemiological triad, the agent factor primarily relates to different types of microorganism and human pathogens that cause disease.[8] In addition, many of the classical treatises of Ayurveda have also described the host factor in the form erratic human behavior responsible for disease causation.
Natural history of disease
Kriyakala is one of the age-old principles described in the classical treatises of Ayurveda.[9]Kriyakala, also known as Shatkriyakala, is predominantly a concept of Ayurveda, which describes different phases of a disease formation in its own unique way. This concept can be compared with natural history of disease in modern medicine. Different phases of Shatkriyakala as compared with natural history of disease are described in [Table 1]. Albeit many authorities compare it simply with pathogenesis, but a meticulous look unravels its relation with natural history of disease. Here, it is important to mention that natural history of a disease includes both prepathogenesis and the pathogenesis stage as well.[10] The concept of Shatkriyakala is of utmost importance from public health intervention point of view and more especially from the perspective of disease control stratagem. Kriyakala gives an opportunity at each stage to halt the disease process by appropriate measure(s). Kriyakala is similar to what has been described as disease cycle or natural history of disease in modern medicine. The stage of Sañcaya and Prakōpa can be comparable with that of the stage of susceptibility. The stage of susceptibility is also called as stage of “Prepathogenesis” by some authorities.[11] In this stage, the risk factors and the host should interact with each other in a suitable and favorable environment for the disease to occur. This has also been rightly said by Acharya Charaka that Bij (seeds) soaked in Bhoomi (land and a proper environment) flourishes only in correct time, and Dosas vitiate (microorganism ought to vitiate Dosas) Dhatus if Dhatu Bala (immunity) depletes in correct time.[12],[13] In the first and second stage of Shatkriyakala, the humors (Dosa) get accumulated and vitiated. Hence, certain intervention measures can be put in-situ to halt the disease progress. As modern medicine emphasizes the primordial and primary prevention at the stage of susceptibility, the same could also be applied at this stage to halt the disease progress. This is very much important from community and individual health perspective. The classical treatises of Ayurveda describe certain intervention measures those can appropriately be applied at this stage. The community level examples are advocacy of proper Dinacharya (daily health promotional activities) and Ritucharya (health promotional activities during specific season), Aahara (specific dietary regimen), Vyayama (exercise), etc. The basic objective of this stage is to prevent disease before it develops so as to maintain health. | Table 1: The concepts of natural history of disease in Ayurveda as compared with “Shatkriyakala”
Click here to view |
At the third and fourth stage, the vitiated or aggravated humors start moving and get settled at a particular organ or organ system. This may deceive a physician owing to its very nature. At this stage, the disease is neither clearly evident nor completely buried. Hence, the diagnosis of a disease becomes difficult at this stage. The modern tools and techniques cannot identify the disease at this stage. This stage is comparable with that of presymptomatic disease where the disease process has already begun, but the overt signs and symptoms are not evident. At this stage, both the primary and secondary prevention measures can be applied. The modes of intervention in secondary prevention are early diagnosis and treatment. The main objective of this intervention is to prevent disease before it develops so as to maintain health.
The fifth stage of Shatkriyakala is Vyakti where the disease is clinically manifested. This is comparable with the stage of clinical disease in natural history of disease. As this stage is marked with clinical signs and symptoms, the modes of intervention at this stage would be early diagnosis and treatment. The examples at the community level are early diagnosis by Nadi Pariksha (examination of pulse), Darshana (inspection), Sparshana (palpation), and Prashna (interrogation), etc., and treatment by Shaman (alleviation) and Sodhana (purification) modalities described in Ayurveda. Strictly speaking, early diagnosis cannot be called as prevention because the disease has already commenced in the host. However, since early diagnosis and treatment intercepts the disease process, it has been included in the schema of prevention, in as much as the goal of prevention is “to oppose or intercept a cause to prevent or dissipate its effect.”[14]
The last stage of Shatkriyakala is Bheda, which is the most dangerous and complicated stage in a disease process. This stage is comparable with the stage of diminished capacity. This stage may end up with recovery, disability, or death. The modes of intervention instituted at this stage, for tertiary prevention, are disability limitation and rehabilitation. The examples at community level are Shaman (alleviation) and Sodhana (purification), Pancakarma cikitsa (five modalities of treatment). The sequences of events leading to disability and handicap have been stated as follows:[14]
Disease → Impairment → Disability → Handicap.
The concept of “disability prevention” relates to all the level of prevention: (a) reducing the occurrence of impairment, viz., immunization against polio (primary prevention); (b) disability limitation by appropriate treatment (secondary prevention); and (c) preventing the transition of disability in to handicap (tertiary prevention).[15]
Causes of epidemic
Ayurveda describes a concept called Janapadodhwans that can approximately be compared with epidemic and its several variants based on the degree and intensity of the event. Janapadodhwans occurs due to vitiation of Vayu, Jala, Desh, and Kala.[16] This concept can very well be compared with environmental pollution or the individual forms of pollution such as air pollution and water pollution. The role of environmental pollution in causation of human disease is undisputable. Over the recent years, despite the major efforts that have been made to clean up the environment, pollution remains a major problem and poses continuing risks to health. The problems are undoubtedly greatest in the developing world, where traditional sources of pollution such as industrial emissions, poor sanitation, inadequate waste management, contaminated water supplies, and exposures to indoor air pollution from biomass fuels affect large numbers of people. Even in developed countries, however, environmental pollution persists, most especially among poorer sectors of society.[17],[18] About 8–9% of the total disease burden may be attributed to pollution, but considerably more in developing countries. Unsafe water, poor sanitation, and poor hygiene are seen to be the major sources of exposure along with indoor air pollution.[19] While Ayurveda summarizes all the relevant concepts in one word as Janapadodhwansa Rogas, modern medicine describes several terminologies to explain the degree and intensity of such events that include outbreak, epidemic, pandemic, and endemic.
Endemic refers to the constant presence of a disease or infectious agent within a given geographic area, or population group. This may also refer to the usual prevalence of a given disease within such area or group. Similarly, hyperendemic refers to a state in which a disease is constantly present at a high incidence and/or prevalence rate. While endemic and its variant hyperendemic refer to constant presence of a health-related event or disease, the terms such as outbreak, epidemic, and pandemic refer to occurrence of more cases of a disease than expected in a given area or among a specific group of people over a particular period in different magnitude. Outbreak is related with local occurrence and pandemic is related with wider occurrence such as several countries or continents.[7],[20],[21]
Classification of disease
Acharya Sushrut, one of the proponents of Ayurveda, has classified diseases into three major categories in his classical treatise, Sushrut Samhita. These are Adhyatmika, Adhibhoutik, and Adhidaibik which are further classified into many subcategories as represented in [Table 2] with their English equivalents.[8]At this juncture, an effort has been made to compare these classifications with that of International Statistical Classification of Diseases and Related Health Problems (ICD), a medical classification list by World Health Organization. Here, the 10th revision of ICD has been used; hence, it is ICD 10. The classification of diseases represents to a system of categories to which morbid entities are assigned according to established criteria. The main purpose of ICD is to permit the systematic recording, analysis, interpretation, and comparison of morbidity and mortality data collected in different countries or areas and at different times. The ICD is used to translate the diagnoses of diseases and other related health problems from word into alphanumeric codes which permit easy storage, retrieval, and analysis of data.[22] Here, in the following [Table 2], an attempt has been made to fit the Ayurvedic types of classification with that of ICD 10 as per its different categories with chapters and blocks. There is no such initiative at any level to design such a classification based on Ayurveda which can also be tried and tested across Ayurveda institutions. | Table 2: Classification of disease in Ayurveda and its comparison with ICD 10
Click here to view |
Modes of communicable disease transmission
Acharya Sushrut, one of the proponents of Ayurveda, has depicted different modes of communicable disease transmission in his classical treatise Sushrut Samhita. He says by physical contact (Gātrasansparśāt), expired air (Niḥśvāsāt), eating with others in same plate (Saha bhōjanāta), sharing a bed (Sahaśayyāsanāccāpi), using clothes, garlands, and paste (Vastamālyānulēpanāt) infectious diseases spread from person to person. These concepts are very much relevant today. Moreover, the modern texts of communicable disease epidemiology describe similar modes of disease transmission. In addition, he has also given examples of some diseases that spread though all these modes, such as different types of skin diseases (Kusṭha), pyrexia (Jvara), pulmonary tuberculosis (PTB) (Sōṣa), and conjunctivitis (Nētrābhisyanda), etc.[23] The texts of epidemiology also reiterate these modes of transmission of these diseases such as skin diseases, conjunctivitis, acute respiratory infections, and PTB, which are caused by direct contact and respiratory routes, respectively. The following [Figure 2] gives a detailed classification of modes of disease transmission with a later note on their approximate Ayurvedic concepts as depicted by Acharya Sushrut.
Here, most of the concepts depicted by Sushrut such as Gātrasansparśāt, Saha bhōjanāta, Sahaśayyāsanāccāpi, Niḥśvāsāt, and Vastamālyānulēpanāt, can be compared with direct modes of communicable disease transmission. At the same time, Vastamālyānulēpanāt and Sahaśayyāsanāccāpi can attribute to some forms of vector-borne disease transmission by both the biological and the mechanical modes as well.
| Conclusion | | |
It is interesting to note that the concepts described centuries back are very much relevant to the contemporary era and their significance cannot be neglected. The concept of Shatkriyakala and classification of disease delineated in classical treatises of Ayurveda are of great significance and their contemporary relevance needs to be capitalized. The strategies described in Shatkriyakala for the prevention and management of clinical entities can be applied at individual and community level which bears considerable public health importance. Similarly, in preference to ICD Ayurveda institutions can adopt their own way of coding diseases as delineated by Acharya Sushrut, which is not currently practiced in any Ayurveda institution in India. Etiology of disease and causes of epidemic described in Ayurveda are also significant as these facts are attested by modern epidemiological theories.
Moreover, the in-depth analysis of the concepts of Ayurveda in the light of modern contemporary science is only possible with those scholars who know both Ayurveda and the relevant concepts in modern medicine. The crux of this point is that Ayurveda requires interdisciplinary research which is the need of the hour and should be performed in chorus with the scholars who can contribute to such research.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
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[Figure 1], [Figure 2]
[Table 1], [Table 2]
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