The General Rule of the Occurrence and Development of Disease
1. Pathogenic Routes and Pathogenic Sites TCM pathogenesis looks for the following pathogenic routes: 1) The External Pathogenic Route The evils can get into the human body via the skin, mouth, and nose, and by contagion, which is considered the external route of the occurrence of diseases. The invasion of the human body by the evils via the skin is well described in chapter 62 in Plain Questions: "When wind and rain attacks people, the evil-qi first gets into the skin, and then into small collaterals; when the small collaterals are filled up, the evil-qi gets into the big collaterals. " "When collaterals are filled up, the evil-qi gets into meridians; when the meridians are filled up, the evil-qi gets into the viscera. " The "transmission along the six meridians" of the cold attack, from the exterior to the interior, starts with the skin, then involves the meridians and finally reaches the viscera; the sequence of the transmission is Taiyang, Yangming, Shaoyang, Taiyin, Shaoyin, and Jueyin. In the case of warm-heat disease, the evil-qi invades the human body via the mouth and nose, just as Dr. Ye Tianshi said in his book Treatise on Epidemic Febrile Diseases:"When the warm evil attacks people, it attacks the lung first." As a matter of fact, many respiratory and digestive infectious diseases found in modern clinical practice spread via the mouth and nose. Diseases due to contagion refer to contagious diseases which find their hosts from person to person. Ancient Chinese doctors clearly understood that all pestilential evils possess the power of contagion. For example, Dr. Chao Yuanfang said in his book General Treatise on the Causes and Symptoms of Diseases: "The pestilential evils catch people in away as if they were exchanging things with people. " Dr. Liu Wansu also said in his book The Causes and Symptoms of Cold-Attack: "How does one identify cold-attack diseases and diseases caused by pestilential evils? The diseases caused by pestilential evils do not manifest floating pulse, but can spread to others. " From what said by the ancient Chinese doctors, we can see the difference between cold-attack diseases and diseases caused by the pestilential evils; that is to say, the latter can spread, and even can cause a large epidemic. The pathogenic routes generally include air contagion, food and drink contagion, and direct contagion. Air Contagion: Ancient Chinese doctors already knew that the air polluted by the evil-qi can pass the evils to people through respiration. For example, Dr. Zhang Jingyue said. "The polluted air can go into the nose, while the nose can pass the evils in the polluted air to the brain; after the evils reaching the brain, they will spread to all meridians,and cause contagious diseases. " The writer of the book Preliminary Study on Scarlet Fever also said: "If a family has a patient of contagious eruptive disease, and someone else in the family catches the same disease by inhaling the air polluted by the patient, we say that the disease is contagious. " There are many contagious diseases, for example,wind-warm disease, measles, and Scarlet fever. Food and Drink Contagion. Food and drink contagion refers to the intake of putre- factive, unclean, and pestilential-evil-polluted food and drink. The pestilential evils, in this case, can directly attack the stomach and intestines and cause diseases of digestive system such as drastic gastrointestinal disorder and dysentery. The medical classic Synopsis of the Golden Chamber points out. "Putrefactive grain food, putrid meat and fish, all do people harm ... All unnatural deaths of domestic animals are caused by pestilential evils; such dead bodies of domestic animals are poisonous, and they should not be eaten." Direct Contagion. Direct contagion is referred to the contagion caused by directly touching those suffering from contagious diseases. As Dr. Wu Youke said in his book Treatise on Pestilence. "If people touch (the host of pestilential evils), they can catch disease. " In addition, the ancient Chinese doctors noticed that the abnormality of the weather is also related to contagious diseases, in addition to the intensity of the pestilential evils and the energetic state of the genuine-qi of the body. The medical classic General Treatise on Causes and Symptoms of Diseases says: "When there is irregular seasonal changes causing abnormal weather, for example, strong wind, heavy rain, and lasting fog and mist, people are liable to catch contagious diseases, regardless whether they are old or young. " The same book also says. "If the seasonal change is abnormal, the irregular weather will appear. In such an environment, people are liable to be attacked by the pestilential evils and catch diseases. The diseases can be contagious and in a critical case they will wipe out a whole family and cause danger to other people. " 2) The Internal Pathogenic Route Many factors, especially mental stress, improper food and drink, too much sex overstrain, over-ease, and advanced age, can affect the body and cause low adaptability to the surroundings; as a result, disharmony, disturbance, or functional decline of the viscera, yin and yang, and qi and blood may take place. This is considered to be the internal route of the occurrence of diseases. Chapter 28 in Spirit Pivot says. "Sexual activities, joy and anger, food and drink, living place, fright and fear, all can become pathogenic factors and cause separation between qi and blood, functional decline of yin and yang, obstruction of meridians and collaterals, blockage of blood vessels, adverse movement of yin and yang, detention of the defence-qi, emptiness of meridians and blood vessels, and irregular circulation of the blood and qi, which leads to abnormality of the body's function. " 3) Traumatic Pathogenic Route Accidental injuries, especially those caused by stumbling and falling, knife-cutting,peak wound, and insect or animal bites, can damage the skin, muscles, meridians and blood vessels, and cause insufficiency of qi and blood. This also leads to the dysfunction of the viscera, yin and yang, and qi and blood, and results in diseases. According to the above-mentioned pathogenic routes, TCM pathogenesis generally divides all diseases into three groups, namely "exogenous seasonal diseases," "endogenous miscellaneous diseases" and "traumatic diseases. " TCM pathogenesis also divides the pathogenic sites into two groups, namely the exterior and the interior, according to different pathogenic routes and levels existing when the body being attacked by the evils.Generally speaking, the problems caused by the evils attacking the skin, meridians, collaterals and the interspace of flesh are called exterior syndromes, while those caused by the evils attacking tendons, bones and the viscera, and those caused by endogenous evils leading to the dysfunction of the viscera, yin and yang, and qi and blood, are called interior syndromes. In accordance with the struggles between the evil-qi and the genuine-qi,there are different types of transmission which determine the advancing, retreating and recovering of diseases. 2. Development and Transmission of Disease TCM holds that the skin, muscles, viscera and other internal organs and tissues all can influence each other via the meridian-collateral system which serves as a connective channel. So, in the development of disease, the transmission of pathologic changes in any pathogenic site will occur between the body's exterior and interior parts, upper and lower parts, and zang-viscera and fu-viscera, via the meridian-collateral system. The Exterior-Interior Transmission. When the evil-qi invades the human body, it often can get into the interior part from the exterior part, and then into the viscera, via the meridians. On the other hand, when there are pathogenic changes of the viscera, the evil-qi can also get into the exterior part from the interior part, and cause various pathologic changes on the skin; for example, the skin rash of measles, which is caused by the evil-qi getting into the exterior part from the interior part. The Upper-Lower Transmission: Different evils attack the human body on differentsites (the upper part or the lower part) via different routes. Chapter 66 in Spirit Pivot says: "Water-dampness attacks the weak body by the lower part; wind and rain attack the weak body by the upper part. " Although the pathogenic sites are different, diseases manifest their whole-body responses and symptoms by the upper-lower transmission via the meridian-collateral system. Chapter 29 in Plain Questions says: "When yang evils invade the human body, they first get into the upper part, and then, into the lower part;when yin evils invade the human body, they first get into the lower part, and then, into the upper part. So, when being attacked by wind, the upper part first suffers; when being attacked by dampness, the lower part first suffers. " The Transmission Between the Zang-Viscera and Fu-Viscera. The visceral pathologic changes mainly refer to the disharmony or disturbance of the zang-visceral and fuvisceral functions, which usually manifests hyperactivity and hypoactivity. In both cases,the visceral pathologic changes can influence each other via the meridian-collateral system. Generally, there are following possible examples: A hyperactive zang-viscus or fu-viscus may affect the related zang-viscus or fu-viscus, and cause its functional disturbance. For example, the hyperactive and adverse liver-qi will cause the spleen's failure of transportation and transformation, with symptoms such as abdominal pain and diarrhea. Clinically, this is termed the "invasion of the spleen by the liver-qi. " In a similar way, a hyperactive zang-viscus or fu-viscus may cause another hyperactive zang-viscus or fu-viscus. For example, the hyperactive liver-qi can be transformed into fire or heat, and causes hyperactive heart-qi with symptoms such as restlessness and insomnia. This is termed "stirring-up of the heart-fire by the liver-fire,"or " flaming of the heart-fire and liver-fire. " A hypoactive zang-viscus may cause another dysfunctional or hypoactive zang-viscus. For example, deficient spleen-qi may cause disturbance of the lung-qi, failure of the lung-qi to disperse and descend, or even the deficiency of the lung-qi, with symptoms such as short breath, low voice, cough, and cough with sputum, which is termed "the lung being affected by deficient spleen. " At the same time, a hypoactive zang-viscus,whose inhibiting ability is decreased, can cause a hyperactive zang-viscus. For example,in a case of insufficient kidney-yin, the kidney-essence fails to nourish the liver-yin, leading to insufficient liver-yin and kidney-yin; then, the liver-yang becomes hyperactive because the insufficient liver-yin and kidney-yin fail to control the liver-yang. In this case, the syndrome of "liver-wind stirring" appears, with symptoms such as dizziness, ringing ear, convulsion and tremor. This is termed "deficiency of yin and over-action of the liver," or "water's failure to nourish wood," or "internal stirring up of the liver-wind." The pathologic change of a diseased zang-viscus can exert its influence on the zangviscus or fu-viscus having an exterior-interior relationship with the diseased zang-viscus via the meridians, and can cause dysfunction of the zang-viscus or fu-viscus being influenced. For example, the heart-fire can move downwards to the small intestine; the deficient spleen can cause stomach's failure to receive food and drink ; the lung in dysfunction can cause the abnormal conduction of the large intestine; and deficiency of kidney-qi can cause dysfunction of the bladder in storing and draining the urine. The advancing, retreating, and recovering of diseases will be introduced in a subsequent chapter entitled "Patho-mechanism. " The modern study of TCM patho-mechanism concerning "the struggle between the evil-qi and the genuine-qi" has been ongoing. According to some scientific research reports, the so-called "genuine-qi" may refer to (a) neurohumoral regulation and automatic maintenance of physiological balance, (b) substance metabolism regulation, (c) regulation of immunity, and (d) detoxifying function and myeloid hematopoiesis. From the above discussion, it may be concluded that the "genuine-qi" means the regulating and defending functions of the body. In addition, through the study of infantile pneumonia, some reports have found that the patients' general health condition, cardiovascular function, and microcirculation state were decisive factors in the occurrence of the disease. Those findings can be used to explain the objectivity of the viewpoints of TCM pathogenesis, that "When the genuine-qi keeps itself inside the body, the evil-qi is unable to launch attacks on the body," and"When the evil-qi is able to launch attacks on the body, the genuine-qi must be weak. "
